Remove old lguest I/O infrrasructure.
This patch gets rid of the old lguest host I/O infrastructure and replaces it with a single hypercall "LHCALL_NOTIFY" which takes an address. The main change is the removal of io.c: that mainly did inter-guest I/O, which virtio doesn't yet support. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
parent
0ca49ca946
commit
15045275c3
8 changed files with 21 additions and 752 deletions
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@ -1,7 +1,7 @@
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# Host requires the other files, which can be a module.
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obj-$(CONFIG_LGUEST) += lg.o
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lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
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segments.o io.o lguest_user.o
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segments.o lguest_user.o
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lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
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@ -202,13 +202,12 @@ int run_guest(struct lguest *lg, unsigned long __user *user)
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if (lg->hcall)
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do_hypercalls(lg);
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/* It's possible the Guest did a SEND_DMA hypercall to the
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/* It's possible the Guest did a NOTIFY hypercall to the
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* Launcher, in which case we return from the read() now. */
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if (lg->dma_is_pending) {
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if (put_user(lg->pending_dma, user) ||
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put_user(lg->pending_key, user+1))
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if (lg->pending_notify) {
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if (put_user(lg->pending_notify, user))
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return -EFAULT;
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return sizeof(unsigned long)*2;
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return sizeof(lg->pending_notify);
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}
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/* Check for signals */
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@ -288,9 +287,6 @@ static int __init init(void)
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if (err)
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goto unmap;
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/* The I/O subsystem needs some things initialized. */
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lguest_io_init();
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/* We might need to reserve an interrupt vector. */
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err = init_interrupts();
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if (err)
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@ -60,22 +60,9 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
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else
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guest_pagetable_flush_user(lg);
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break;
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case LHCALL_BIND_DMA:
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/* BIND_DMA really wants four arguments, but it's the only call
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* which does. So the Guest packs the number of buffers and
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* the interrupt number into the final argument, and we decode
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* it here. This can legitimately fail, since we currently
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* place a limit on the number of DMA pools a Guest can have.
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* So we return true or false from this call. */
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args->arg0 = bind_dma(lg, args->arg1, args->arg2,
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args->arg3 >> 8, args->arg3 & 0xFF);
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break;
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/* All these calls simply pass the arguments through to the right
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* routines. */
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case LHCALL_SEND_DMA:
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send_dma(lg, args->arg1, args->arg2);
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break;
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case LHCALL_NEW_PGTABLE:
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guest_new_pagetable(lg, args->arg1);
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break;
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@ -99,6 +86,9 @@ static void do_hcall(struct lguest *lg, struct hcall_args *args)
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/* Similarly, this sets the halted flag for run_guest(). */
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lg->halted = 1;
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break;
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case LHCALL_NOTIFY:
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lg->pending_notify = args->arg1;
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break;
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default:
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if (lguest_arch_do_hcall(lg, args))
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kill_guest(lg, "Bad hypercall %li\n", args->arg0);
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@ -156,9 +146,9 @@ static void do_async_hcalls(struct lguest *lg)
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break;
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}
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/* Stop doing hypercalls if we've just done a DMA to the
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* Launcher: it needs to service this first. */
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if (lg->dma_is_pending)
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/* Stop doing hypercalls if they want to notify the Launcher:
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* it needs to service this first. */
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if (lg->pending_notify)
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break;
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}
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}
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@ -220,9 +210,9 @@ void do_hypercalls(struct lguest *lg)
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do_async_hcalls(lg);
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/* If we stopped reading the hypercall ring because the Guest did a
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* SEND_DMA to the Launcher, we want to return now. Otherwise we do
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* NOTIFY to the Launcher, we want to return now. Otherwise we do
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* the hypercall. */
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if (!lg->dma_is_pending) {
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if (!lg->pending_notify) {
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do_hcall(lg, lg->hcall);
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/* Tricky point: we reset the hcall pointer to mark the
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* hypercall as "done". We use the hcall pointer rather than
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@ -1,628 +0,0 @@
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/*P:300 The I/O mechanism in lguest is simple yet flexible, allowing the Guest
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* to talk to the Launcher or directly to another Guest. It uses familiar
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* concepts of DMA and interrupts, plus some neat code stolen from
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* futexes... :*/
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/* Copyright (C) 2006 Rusty Russell IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <linux/types.h>
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#include <linux/futex.h>
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#include <linux/jhash.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/uaccess.h>
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#include "lg.h"
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/*L:300
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* I/O
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*
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* Getting data in and out of the Guest is quite an art. There are numerous
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* ways to do it, and they all suck differently. We try to keep things fairly
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* close to "real" hardware so our Guest's drivers don't look like an alien
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* visitation in the middle of the Linux code, and yet make sure that Guests
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* can talk directly to other Guests, not just the Launcher.
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*
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* To do this, the Guest gives us a key when it binds or sends DMA buffers.
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* The key corresponds to a "physical" address inside the Guest (ie. a virtual
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* address inside the Launcher process). We don't, however, use this key
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* directly.
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*
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* We want Guests which share memory to be able to DMA to each other: two
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* Launchers can mmap memory the same file, then the Guests can communicate.
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* Fortunately, the futex code provides us with a way to get a "union
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* futex_key" corresponding to the memory lying at a virtual address: if the
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* two processes share memory, the "union futex_key" for that memory will match
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* even if the memory is mapped at different addresses in each. So we always
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* convert the keys to "union futex_key"s to compare them.
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*
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* Before we dive into this though, we need to look at another set of helper
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* routines used throughout the Host kernel code to access Guest memory.
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:*/
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static struct list_head dma_hash[61];
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/* An unfortunate side effect of the Linux double-linked list implementation is
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* that there's no good way to statically initialize an array of linked
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* lists. */
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void lguest_io_init(void)
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{
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(dma_hash); i++)
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INIT_LIST_HEAD(&dma_hash[i]);
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}
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/* FIXME: allow multi-page lengths. */
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static int check_dma_list(struct lguest *lg, const struct lguest_dma *dma)
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{
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unsigned int i;
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for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
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if (!dma->len[i])
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return 1;
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if (!lguest_address_ok(lg, dma->addr[i], dma->len[i]))
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goto kill;
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if (dma->len[i] > PAGE_SIZE)
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goto kill;
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/* We could do over a page, but is it worth it? */
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if ((dma->addr[i] % PAGE_SIZE) + dma->len[i] > PAGE_SIZE)
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goto kill;
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}
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return 1;
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kill:
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kill_guest(lg, "bad DMA entry: %u@%#lx", dma->len[i], dma->addr[i]);
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return 0;
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}
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/*L:330 This is our hash function, using the wonderful Jenkins hash.
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*
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* The futex key is a union with three parts: an unsigned long word, a pointer,
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* and an int "offset". We could use jhash_2words() which takes three u32s.
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* (Ok, the hash functions are great: the naming sucks though).
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*
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* It's nice to be portable to 64-bit platforms, so we use the more generic
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* jhash2(), which takes an array of u32, the number of u32s, and an initial
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* u32 to roll in. This is uglier, but breaks down to almost the same code on
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* 32-bit platforms like this one.
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*
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* We want a position in the array, so we modulo ARRAY_SIZE(dma_hash) (ie. 61).
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*/
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static unsigned int hash(const union futex_key *key)
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{
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return jhash2((u32*)&key->both.word,
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(sizeof(key->both.word)+sizeof(key->both.ptr))/4,
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key->both.offset)
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% ARRAY_SIZE(dma_hash);
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}
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/* This is a convenience routine to compare two keys. It's a much bemoaned C
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* weakness that it doesn't allow '==' on structures or unions, so we have to
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* open-code it like this. */
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static inline int key_eq(const union futex_key *a, const union futex_key *b)
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{
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return (a->both.word == b->both.word
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&& a->both.ptr == b->both.ptr
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&& a->both.offset == b->both.offset);
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}
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/*L:360 OK, when we need to actually free up a Guest's DMA array we do several
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* things, so we have a convenient function to do it.
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*
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* The caller must hold a read lock on dmainfo owner's current->mm->mmap_sem
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* for the drop_futex_key_refs(). */
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static void unlink_dma(struct lguest_dma_info *dmainfo)
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{
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/* You locked this too, right? */
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BUG_ON(!mutex_is_locked(&lguest_lock));
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/* This is how we know that the entry is free. */
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dmainfo->interrupt = 0;
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/* Remove it from the hash table. */
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list_del(&dmainfo->list);
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/* Drop the references we were holding (to the inode or mm). */
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drop_futex_key_refs(&dmainfo->key);
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}
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/*L:350 This is the routine which we call when the Guest asks to unregister a
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* DMA array attached to a given key. Returns true if the array was found. */
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static int unbind_dma(struct lguest *lg,
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const union futex_key *key,
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unsigned long dmas)
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{
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int i, ret = 0;
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/* We don't bother with the hash table, just look through all this
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* Guest's DMA arrays. */
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for (i = 0; i < LGUEST_MAX_DMA; i++) {
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/* In theory it could have more than one array on the same key,
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* or one array on multiple keys, so we check both */
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if (key_eq(key, &lg->dma[i].key) && dmas == lg->dma[i].dmas) {
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unlink_dma(&lg->dma[i]);
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ret = 1;
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break;
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}
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}
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return ret;
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}
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/*L:340 BIND_DMA: this is the hypercall which sets up an array of "struct
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* lguest_dma" for receiving I/O.
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*
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* The Guest wants to bind an array of "struct lguest_dma"s to a particular key
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* to receive input. This only happens when the Guest is setting up a new
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* device, so it doesn't have to be very fast.
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*
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* It returns 1 on a successful registration (it can fail if we hit the limit
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* of registrations for this Guest).
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*/
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int bind_dma(struct lguest *lg,
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unsigned long ukey, unsigned long dmas, u16 numdmas, u8 interrupt)
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{
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unsigned int i;
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int ret = 0;
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union futex_key key;
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/* Futex code needs the mmap_sem. */
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struct rw_semaphore *fshared = ¤t->mm->mmap_sem;
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/* Invalid interrupt? (We could kill the guest here). */
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if (interrupt >= LGUEST_IRQS)
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return 0;
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/* We need to grab the Big Lguest Lock, because other Guests may be
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* trying to look through this Guest's DMAs to send something while
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* we're doing this. */
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mutex_lock(&lguest_lock);
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down_read(fshared);
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if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) {
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kill_guest(lg, "bad dma key %#lx", ukey);
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goto unlock;
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}
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/* We want to keep this key valid once we drop mmap_sem, so we have to
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* hold a reference. */
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get_futex_key_refs(&key);
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/* If the Guest specified an interrupt of 0, that means they want to
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* unregister this array of "struct lguest_dma"s. */
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if (interrupt == 0)
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ret = unbind_dma(lg, &key, dmas);
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else {
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/* Look through this Guest's dma array for an unused entry. */
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for (i = 0; i < LGUEST_MAX_DMA; i++) {
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/* If the interrupt is non-zero, the entry is already
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* used. */
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if (lg->dma[i].interrupt)
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continue;
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/* OK, a free one! Fill on our details. */
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lg->dma[i].dmas = dmas;
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lg->dma[i].num_dmas = numdmas;
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lg->dma[i].next_dma = 0;
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lg->dma[i].key = key;
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lg->dma[i].owner = lg;
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lg->dma[i].interrupt = interrupt;
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/* Now we add it to the hash table: the position
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* depends on the futex key that we got. */
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list_add(&lg->dma[i].list, &dma_hash[hash(&key)]);
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/* Success! */
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ret = 1;
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goto unlock;
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}
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}
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/* If we didn't find a slot to put the key in, drop the reference
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* again. */
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drop_futex_key_refs(&key);
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unlock:
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/* Unlock and out. */
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up_read(fshared);
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mutex_unlock(&lguest_lock);
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return ret;
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}
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/*L:385 Note that our routines to access a different Guest's memory are called
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* lgread_other() and lgwrite_other(): these names emphasize that they are only
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* used when the Guest is *not* the current Guest.
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*
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* The interface for copying from another process's memory is called
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* access_process_vm(), with a final argument of 0 for a read, and 1 for a
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* write.
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*
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* We need lgread_other() to read the destination Guest's "struct lguest_dma"
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* array. */
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static int lgread_other(struct lguest *lg,
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void *buf, u32 addr, unsigned bytes)
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{
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if (!lguest_address_ok(lg, addr, bytes)
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|| access_process_vm(lg->tsk, (unsigned long)lg->mem_base + addr,
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buf, bytes, 0) != bytes) {
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memset(buf, 0, bytes);
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kill_guest(lg, "bad address in registered DMA struct");
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return 0;
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}
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return 1;
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}
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/* "lgwrite()" to another Guest: used to update the destination "used_len" once
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* we've transferred data into the buffer. */
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static int lgwrite_other(struct lguest *lg, u32 addr,
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const void *buf, unsigned bytes)
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{
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if (!lguest_address_ok(lg, addr, bytes)
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|| access_process_vm(lg->tsk, (unsigned long)lg->mem_base + addr,
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(void *)buf, bytes, 1) != bytes) {
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kill_guest(lg, "bad address writing to registered DMA");
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return 0;
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}
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return 1;
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}
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/*L:400 This is the generic engine which copies from a source "struct
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* lguest_dma" from this Guest into another Guest's "struct lguest_dma". The
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* destination Guest's pages have already been mapped, as contained in the
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* pages array.
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*
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* If you're wondering if there's a nice "copy from one process to another"
|
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* routine, so was I. But Linux isn't really set up to copy between two
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* unrelated processes, so we have to write it ourselves.
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*/
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static u32 copy_data(struct lguest *srclg,
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const struct lguest_dma *src,
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const struct lguest_dma *dst,
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struct page *pages[])
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{
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unsigned int totlen, si, di, srcoff, dstoff;
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void *maddr = NULL;
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/* We return the total length transferred. */
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totlen = 0;
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/* We keep indexes into the source and destination "struct lguest_dma",
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* and an offset within each region. */
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si = di = 0;
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srcoff = dstoff = 0;
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/* We loop until the source or destination is exhausted. */
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while (si < LGUEST_MAX_DMA_SECTIONS && src->len[si]
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&& di < LGUEST_MAX_DMA_SECTIONS && dst->len[di]) {
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/* We can only transfer the rest of the src buffer, or as much
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* as will fit into the destination buffer. */
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u32 len = min(src->len[si] - srcoff, dst->len[di] - dstoff);
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/* For systems using "highmem" we need to use kmap() to access
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* the page we want. We often use the same page over and over,
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* so rather than kmap() it on every loop, we set the maddr
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* pointer to NULL when we need to move to the next
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* destination page. */
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if (!maddr)
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maddr = kmap(pages[di]);
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/* Copy directly from (this Guest's) source address to the
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* destination Guest's kmap()ed buffer. Note that maddr points
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* to the start of the page: we need to add the offset of the
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* destination address and offset within the buffer. */
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/* FIXME: This is not completely portable. I looked at
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* copy_to_user_page(), and some arch's seem to need special
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* flushes. x86 is fine. */
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if (copy_from_user(maddr + (dst->addr[di] + dstoff)%PAGE_SIZE,
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srclg->mem_base+src->addr[si], len) != 0) {
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/* If a copy failed, it's the source's fault. */
|
||||
kill_guest(srclg, "bad address in sending DMA");
|
||||
totlen = 0;
|
||||
break;
|
||||
}
|
||||
|
||||
/* Increment the total and src & dst offsets */
|
||||
totlen += len;
|
||||
srcoff += len;
|
||||
dstoff += len;
|
||||
|
||||
/* Presumably we reached the end of the src or dest buffers: */
|
||||
if (srcoff == src->len[si]) {
|
||||
/* Move to the next buffer at offset 0 */
|
||||
si++;
|
||||
srcoff = 0;
|
||||
}
|
||||
if (dstoff == dst->len[di]) {
|
||||
/* We need to unmap that destination page and reset
|
||||
* maddr ready for the next one. */
|
||||
kunmap(pages[di]);
|
||||
maddr = NULL;
|
||||
di++;
|
||||
dstoff = 0;
|
||||
}
|
||||
}
|
||||
|
||||
/* If we still had a page mapped at the end, unmap now. */
|
||||
if (maddr)
|
||||
kunmap(pages[di]);
|
||||
|
||||
return totlen;
|
||||
}
|
||||
|
||||
/*L:390 This is how we transfer a "struct lguest_dma" from the source Guest
|
||||
* (the current Guest which called SEND_DMA) to another Guest. */
|
||||
static u32 do_dma(struct lguest *srclg, const struct lguest_dma *src,
|
||||
struct lguest *dstlg, const struct lguest_dma *dst)
|
||||
{
|
||||
int i;
|
||||
u32 ret;
|
||||
struct page *pages[LGUEST_MAX_DMA_SECTIONS];
|
||||
|
||||
/* We check that both source and destination "struct lguest_dma"s are
|
||||
* within the bounds of the source and destination Guests */
|
||||
if (!check_dma_list(dstlg, dst) || !check_dma_list(srclg, src))
|
||||
return 0;
|
||||
|
||||
/* We need to map the pages which correspond to each parts of
|
||||
* destination buffer. */
|
||||
for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
|
||||
if (dst->len[i] == 0)
|
||||
break;
|
||||
/* get_user_pages() is a complicated function, especially since
|
||||
* we only want a single page. But it works, and returns the
|
||||
* number of pages. Note that we're holding the destination's
|
||||
* mmap_sem, as get_user_pages() requires. */
|
||||
if (get_user_pages(dstlg->tsk, dstlg->mm,
|
||||
(unsigned long)dstlg->mem_base+dst->addr[i],
|
||||
1, 1, 1, pages+i, NULL)
|
||||
!= 1) {
|
||||
/* This means the destination gave us a bogus buffer */
|
||||
kill_guest(dstlg, "Error mapping DMA pages");
|
||||
ret = 0;
|
||||
goto drop_pages;
|
||||
}
|
||||
}
|
||||
|
||||
/* Now copy the data until we run out of src or dst. */
|
||||
ret = copy_data(srclg, src, dst, pages);
|
||||
|
||||
drop_pages:
|
||||
while (--i >= 0)
|
||||
put_page(pages[i]);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*L:380 Transferring data from one Guest to another is not as simple as I'd
|
||||
* like. We've found the "struct lguest_dma_info" bound to the same address as
|
||||
* the send, we need to copy into it.
|
||||
*
|
||||
* This function returns true if the destination array was empty. */
|
||||
static int dma_transfer(struct lguest *srclg,
|
||||
unsigned long udma,
|
||||
struct lguest_dma_info *dst)
|
||||
{
|
||||
struct lguest_dma dst_dma, src_dma;
|
||||
struct lguest *dstlg;
|
||||
u32 i, dma = 0;
|
||||
|
||||
/* From the "struct lguest_dma_info" we found in the hash, grab the
|
||||
* Guest. */
|
||||
dstlg = dst->owner;
|
||||
/* Read in the source "struct lguest_dma" handed to SEND_DMA. */
|
||||
lgread(srclg, &src_dma, udma, sizeof(src_dma));
|
||||
|
||||
/* We need the destination's mmap_sem, and we already hold the source's
|
||||
* mmap_sem for the futex key lookup. Normally this would suggest that
|
||||
* we could deadlock if the destination Guest was trying to send to
|
||||
* this source Guest at the same time, which is another reason that all
|
||||
* I/O is done under the big lguest_lock. */
|
||||
down_read(&dstlg->mm->mmap_sem);
|
||||
|
||||
/* Look through the destination DMA array for an available buffer. */
|
||||
for (i = 0; i < dst->num_dmas; i++) {
|
||||
/* We keep a "next_dma" pointer which often helps us avoid
|
||||
* looking at lots of previously-filled entries. */
|
||||
dma = (dst->next_dma + i) % dst->num_dmas;
|
||||
if (!lgread_other(dstlg, &dst_dma,
|
||||
dst->dmas + dma * sizeof(struct lguest_dma),
|
||||
sizeof(dst_dma))) {
|
||||
goto fail;
|
||||
}
|
||||
if (!dst_dma.used_len)
|
||||
break;
|
||||
}
|
||||
|
||||
/* If we found a buffer, we do the actual data copy. */
|
||||
if (i != dst->num_dmas) {
|
||||
unsigned long used_lenp;
|
||||
unsigned int ret;
|
||||
|
||||
ret = do_dma(srclg, &src_dma, dstlg, &dst_dma);
|
||||
/* Put used length in the source "struct lguest_dma"'s used_len
|
||||
* field. It's a little tricky to figure out where that is,
|
||||
* though. */
|
||||
lgwrite_u32(srclg,
|
||||
udma+offsetof(struct lguest_dma, used_len), ret);
|
||||
/* Tranferring 0 bytes is OK if the source buffer was empty. */
|
||||
if (ret == 0 && src_dma.len[0] != 0)
|
||||
goto fail;
|
||||
|
||||
/* The destination Guest might be running on a different CPU:
|
||||
* we have to make sure that it will see the "used_len" field
|
||||
* change to non-zero *after* it sees the data we copied into
|
||||
* the buffer. Hence a write memory barrier. */
|
||||
wmb();
|
||||
/* Figuring out where the destination's used_len field for this
|
||||
* "struct lguest_dma" in the array is also a little ugly. */
|
||||
used_lenp = dst->dmas
|
||||
+ dma * sizeof(struct lguest_dma)
|
||||
+ offsetof(struct lguest_dma, used_len);
|
||||
lgwrite_other(dstlg, used_lenp, &ret, sizeof(ret));
|
||||
/* Move the cursor for next time. */
|
||||
dst->next_dma++;
|
||||
}
|
||||
up_read(&dstlg->mm->mmap_sem);
|
||||
|
||||
/* We trigger the destination interrupt, even if the destination was
|
||||
* empty and we didn't transfer anything: this gives them a chance to
|
||||
* wake up and refill. */
|
||||
set_bit(dst->interrupt, dstlg->irqs_pending);
|
||||
/* Wake up the destination process. */
|
||||
wake_up_process(dstlg->tsk);
|
||||
/* If we passed the last "struct lguest_dma", the receive had no
|
||||
* buffers left. */
|
||||
return i == dst->num_dmas;
|
||||
|
||||
fail:
|
||||
up_read(&dstlg->mm->mmap_sem);
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*L:370 This is the counter-side to the BIND_DMA hypercall; the SEND_DMA
|
||||
* hypercall. We find out who's listening, and send to them. */
|
||||
void send_dma(struct lguest *lg, unsigned long ukey, unsigned long udma)
|
||||
{
|
||||
union futex_key key;
|
||||
int empty = 0;
|
||||
struct rw_semaphore *fshared = ¤t->mm->mmap_sem;
|
||||
|
||||
again:
|
||||
mutex_lock(&lguest_lock);
|
||||
down_read(fshared);
|
||||
/* Get the futex key for the key the Guest gave us */
|
||||
if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) {
|
||||
kill_guest(lg, "bad sending DMA key");
|
||||
goto unlock;
|
||||
}
|
||||
/* Since the key must be a multiple of 4, the futex key uses the lower
|
||||
* bit of the "offset" field (which would always be 0) to indicate a
|
||||
* mapping which is shared with other processes (ie. Guests). */
|
||||
if (key.shared.offset & 1) {
|
||||
struct lguest_dma_info *i;
|
||||
/* Look through the hash for other Guests. */
|
||||
list_for_each_entry(i, &dma_hash[hash(&key)], list) {
|
||||
/* Don't send to ourselves (would deadlock). */
|
||||
if (i->owner->mm == lg->mm)
|
||||
continue;
|
||||
if (!key_eq(&key, &i->key))
|
||||
continue;
|
||||
|
||||
/* If dma_transfer() tells us the destination has no
|
||||
* available buffers, we increment "empty". */
|
||||
empty += dma_transfer(lg, udma, i);
|
||||
break;
|
||||
}
|
||||
/* If the destination is empty, we release our locks and
|
||||
* give the destination Guest a brief chance to restock. */
|
||||
if (empty == 1) {
|
||||
/* Give any recipients one chance to restock. */
|
||||
up_read(¤t->mm->mmap_sem);
|
||||
mutex_unlock(&lguest_lock);
|
||||
/* Next time, we won't try again. */
|
||||
empty++;
|
||||
goto again;
|
||||
}
|
||||
} else {
|
||||
/* Private mapping: Guest is sending to its Launcher. We set
|
||||
* the "dma_is_pending" flag so that the main loop will exit
|
||||
* and the Launcher's read() from /dev/lguest will return. */
|
||||
lg->dma_is_pending = 1;
|
||||
lg->pending_dma = udma;
|
||||
lg->pending_key = ukey;
|
||||
}
|
||||
unlock:
|
||||
up_read(fshared);
|
||||
mutex_unlock(&lguest_lock);
|
||||
}
|
||||
/*:*/
|
||||
|
||||
void release_all_dma(struct lguest *lg)
|
||||
{
|
||||
unsigned int i;
|
||||
|
||||
BUG_ON(!mutex_is_locked(&lguest_lock));
|
||||
|
||||
down_read(&lg->mm->mmap_sem);
|
||||
for (i = 0; i < LGUEST_MAX_DMA; i++) {
|
||||
if (lg->dma[i].interrupt)
|
||||
unlink_dma(&lg->dma[i]);
|
||||
}
|
||||
up_read(&lg->mm->mmap_sem);
|
||||
}
|
||||
|
||||
/*M:007 We only return a single DMA buffer to the Launcher, but it would be
|
||||
* more efficient to return a pointer to the entire array of DMA buffers, which
|
||||
* it can cache and choose one whenever it wants.
|
||||
*
|
||||
* Currently the Launcher uses a write to /dev/lguest, and the return value is
|
||||
* the address of the DMA structure with the interrupt number placed in
|
||||
* dma->used_len. If we wanted to return the entire array, we need to return
|
||||
* the address, array size and interrupt number: this seems to require an
|
||||
* ioctl(). :*/
|
||||
|
||||
/*L:320 This routine looks for a DMA buffer registered by the Guest on the
|
||||
* given key (using the BIND_DMA hypercall). */
|
||||
unsigned long get_dma_buffer(struct lguest *lg,
|
||||
unsigned long ukey, unsigned long *interrupt)
|
||||
{
|
||||
unsigned long ret = 0;
|
||||
union futex_key key;
|
||||
struct lguest_dma_info *i;
|
||||
struct rw_semaphore *fshared = ¤t->mm->mmap_sem;
|
||||
|
||||
/* Take the Big Lguest Lock to stop other Guests sending this Guest DMA
|
||||
* at the same time. */
|
||||
mutex_lock(&lguest_lock);
|
||||
/* To match between Guests sharing the same underlying memory we steal
|
||||
* code from the futex infrastructure. This requires that we hold the
|
||||
* "mmap_sem" for our process (the Launcher), and pass it to the futex
|
||||
* code. */
|
||||
down_read(fshared);
|
||||
|
||||
/* This can fail if it's not a valid address, or if the address is not
|
||||
* divisible by 4 (the futex code needs that, we don't really). */
|
||||
if (get_futex_key(lg->mem_base + ukey, fshared, &key) != 0) {
|
||||
kill_guest(lg, "bad registered DMA buffer");
|
||||
goto unlock;
|
||||
}
|
||||
/* Search the hash table for matching entries (the Launcher can only
|
||||
* send to its own Guest for the moment, so the entry must be for this
|
||||
* Guest) */
|
||||
list_for_each_entry(i, &dma_hash[hash(&key)], list) {
|
||||
if (key_eq(&key, &i->key) && i->owner == lg) {
|
||||
unsigned int j;
|
||||
/* Look through the registered DMA array for an
|
||||
* available buffer. */
|
||||
for (j = 0; j < i->num_dmas; j++) {
|
||||
struct lguest_dma dma;
|
||||
|
||||
ret = i->dmas + j * sizeof(struct lguest_dma);
|
||||
lgread(lg, &dma, ret, sizeof(dma));
|
||||
if (dma.used_len == 0)
|
||||
break;
|
||||
}
|
||||
/* Store the interrupt the Guest wants when the buffer
|
||||
* is used. */
|
||||
*interrupt = i->interrupt;
|
||||
break;
|
||||
}
|
||||
}
|
||||
unlock:
|
||||
up_read(fshared);
|
||||
mutex_unlock(&lguest_lock);
|
||||
return ret;
|
||||
}
|
||||
/*:*/
|
||||
|
||||
/*L:410 This really has completed the Launcher. Not only have we now finished
|
||||
* the longest chapter in our journey, but this also means we are over halfway
|
||||
* through!
|
||||
*
|
||||
* Enough prevaricating around the bush: it is time for us to dive into the
|
||||
* core of the Host, in "make Host".
|
||||
*/
|
||||
|
|
@ -5,7 +5,6 @@
|
|||
#include <linux/types.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/stringify.h>
|
||||
#include <linux/futex.h>
|
||||
#include <linux/lguest.h>
|
||||
#include <linux/lguest_launcher.h>
|
||||
#include <linux/wait.h>
|
||||
|
|
@ -17,17 +16,6 @@
|
|||
void free_pagetables(void);
|
||||
int init_pagetables(struct page **switcher_page, unsigned int pages);
|
||||
|
||||
struct lguest_dma_info
|
||||
{
|
||||
struct list_head list;
|
||||
union futex_key key;
|
||||
unsigned long dmas;
|
||||
struct lguest *owner;
|
||||
u16 next_dma;
|
||||
u16 num_dmas;
|
||||
u8 interrupt; /* 0 when not registered */
|
||||
};
|
||||
|
||||
struct pgdir
|
||||
{
|
||||
unsigned long gpgdir;
|
||||
|
|
@ -90,15 +78,11 @@ struct lguest
|
|||
struct task_struct *wake;
|
||||
|
||||
unsigned long noirq_start, noirq_end;
|
||||
int dma_is_pending;
|
||||
unsigned long pending_dma; /* struct lguest_dma */
|
||||
unsigned long pending_key; /* address they're sending to */
|
||||
unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
|
||||
|
||||
unsigned int stack_pages;
|
||||
u32 tsc_khz;
|
||||
|
||||
struct lguest_dma_info dma[LGUEST_MAX_DMA];
|
||||
|
||||
/* Dead? */
|
||||
const char *dead;
|
||||
|
||||
|
|
@ -184,15 +168,6 @@ extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
|
|||
int lguest_device_init(void);
|
||||
void lguest_device_remove(void);
|
||||
|
||||
/* io.c: */
|
||||
void lguest_io_init(void);
|
||||
int bind_dma(struct lguest *lg,
|
||||
unsigned long key, unsigned long udma, u16 numdmas, u8 interrupt);
|
||||
void send_dma(struct lguest *info, unsigned long key, unsigned long udma);
|
||||
void release_all_dma(struct lguest *lg);
|
||||
unsigned long get_dma_buffer(struct lguest *lg, unsigned long key,
|
||||
unsigned long *interrupt);
|
||||
|
||||
/* hypercalls.c: */
|
||||
void do_hypercalls(struct lguest *lg);
|
||||
void write_timestamp(struct lguest *lg);
|
||||
|
|
|
|||
|
|
@ -2,37 +2,12 @@
|
|||
* controls and communicates with the Guest. For example, the first write will
|
||||
* tell us the Guest's memory layout, pagetable, entry point and kernel address
|
||||
* offset. A read will run the Guest until something happens, such as a signal
|
||||
* or the Guest doing a DMA out to the Launcher. Writes are also used to get a
|
||||
* DMA buffer registered by the Guest and to send the Guest an interrupt. :*/
|
||||
* or the Guest doing a NOTIFY out to the Launcher. :*/
|
||||
#include <linux/uaccess.h>
|
||||
#include <linux/miscdevice.h>
|
||||
#include <linux/fs.h>
|
||||
#include "lg.h"
|
||||
|
||||
/*L:310 To send DMA into the Guest, the Launcher needs to be able to ask for a
|
||||
* DMA buffer. This is done by writing LHREQ_GETDMA and the key to
|
||||
* /dev/lguest. */
|
||||
static long user_get_dma(struct lguest *lg, const unsigned long __user *input)
|
||||
{
|
||||
unsigned long key, udma, irq;
|
||||
|
||||
/* Fetch the key they wrote to us. */
|
||||
if (get_user(key, input) != 0)
|
||||
return -EFAULT;
|
||||
/* Look for a free Guest DMA buffer bound to that key. */
|
||||
udma = get_dma_buffer(lg, key, &irq);
|
||||
if (!udma)
|
||||
return -ENOENT;
|
||||
|
||||
/* We need to tell the Launcher what interrupt the Guest expects after
|
||||
* the buffer is filled. We stash it in udma->used_len. */
|
||||
lgwrite_u32(lg, udma + offsetof(struct lguest_dma, used_len), irq);
|
||||
|
||||
/* The (guest-physical) address of the DMA buffer is returned from
|
||||
* the write(). */
|
||||
return udma;
|
||||
}
|
||||
|
||||
/*L:315 To force the Guest to stop running and return to the Launcher, the
|
||||
* Waker sets writes LHREQ_BREAK and the value "1" to /dev/lguest. The
|
||||
* Launcher then writes LHREQ_BREAK and "0" to release the Waker. */
|
||||
|
|
@ -102,10 +77,10 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
|
|||
return len;
|
||||
}
|
||||
|
||||
/* If we returned from read() last time because the Guest sent DMA,
|
||||
/* If we returned from read() last time because the Guest notified,
|
||||
* clear the flag. */
|
||||
if (lg->dma_is_pending)
|
||||
lg->dma_is_pending = 0;
|
||||
if (lg->pending_notify)
|
||||
lg->pending_notify = 0;
|
||||
|
||||
/* Run the Guest until something interesting happens. */
|
||||
return run_guest(lg, (unsigned long __user *)user);
|
||||
|
|
@ -216,7 +191,7 @@ static int initialize(struct file *file, const unsigned long __user *input)
|
|||
/*L:010 The first operation the Launcher does must be a write. All writes
|
||||
* start with a 32 bit number: for the first write this must be
|
||||
* LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use
|
||||
* writes of other values to get DMA buffers and send interrupts. */
|
||||
* writes of other values to send interrupts. */
|
||||
static ssize_t write(struct file *file, const char __user *in,
|
||||
size_t size, loff_t *off)
|
||||
{
|
||||
|
|
@ -245,8 +220,6 @@ static ssize_t write(struct file *file, const char __user *in,
|
|||
switch (req) {
|
||||
case LHREQ_INITIALIZE:
|
||||
return initialize(file, input);
|
||||
case LHREQ_GETDMA:
|
||||
return user_get_dma(lg, input);
|
||||
case LHREQ_IRQ:
|
||||
return user_send_irq(lg, input);
|
||||
case LHREQ_BREAK:
|
||||
|
|
@ -276,8 +249,6 @@ static int close(struct inode *inode, struct file *file)
|
|||
mutex_lock(&lguest_lock);
|
||||
/* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */
|
||||
hrtimer_cancel(&lg->hrt);
|
||||
/* Free any DMA buffers the Guest had bound. */
|
||||
release_all_dma(lg);
|
||||
/* Free up the shadow page tables for the Guest. */
|
||||
free_guest_pagetable(lg);
|
||||
/* Now all the memory cleanups are done, it's safe to release the
|
||||
|
|
|
|||
|
|
@ -13,11 +13,10 @@
|
|||
#define LHCALL_TS 8
|
||||
#define LHCALL_SET_CLOCKEVENT 9
|
||||
#define LHCALL_HALT 10
|
||||
#define LHCALL_BIND_DMA 12
|
||||
#define LHCALL_SEND_DMA 13
|
||||
#define LHCALL_SET_PTE 14
|
||||
#define LHCALL_SET_PMD 15
|
||||
#define LHCALL_LOAD_TLS 16
|
||||
#define LHCALL_NOTIFY 17
|
||||
|
||||
/*G:031 First, how does our Guest contact the Host to ask for privileged
|
||||
* operations? There are two ways: the direct way is to make a "hypercall",
|
||||
|
|
|
|||
|
|
@ -10,40 +10,6 @@
|
|||
/* How many devices? Assume each one wants up to two dma arrays per device. */
|
||||
#define LGUEST_MAX_DEVICES (LGUEST_MAX_DMA/2)
|
||||
|
||||
/*D:200
|
||||
* Lguest I/O
|
||||
*
|
||||
* The lguest I/O mechanism is the only way Guests can talk to devices. There
|
||||
* are two hypercalls involved: SEND_DMA for output and BIND_DMA for input. In
|
||||
* each case, "struct lguest_dma" describes the buffer: this contains 16
|
||||
* addr/len pairs, and if there are fewer buffer elements the len array is
|
||||
* terminated with a 0.
|
||||
*
|
||||
* I/O is organized by keys: BIND_DMA attaches buffers to a particular key, and
|
||||
* SEND_DMA transfers to buffers bound to particular key. By convention, keys
|
||||
* correspond to a physical address within the device's page. This means that
|
||||
* devices will never accidentally end up with the same keys, and allows the
|
||||
* Host use The Futex Trick (as we'll see later in our journey).
|
||||
*
|
||||
* SEND_DMA simply indicates a key to send to, and the physical address of the
|
||||
* "struct lguest_dma" to send. The Host will write the number of bytes
|
||||
* transferred into the "struct lguest_dma"'s used_len member.
|
||||
*
|
||||
* BIND_DMA indicates a key to bind to, a pointer to an array of "struct
|
||||
* lguest_dma"s ready for receiving, the size of that array, and an interrupt
|
||||
* to trigger when data is received. The Host will only allow transfers into
|
||||
* buffers with a used_len of zero: it then sets used_len to the number of
|
||||
* bytes transferred and triggers the interrupt for the Guest to process the
|
||||
* new input. */
|
||||
struct lguest_dma
|
||||
{
|
||||
/* 0 if free to be used, filled by the Host. */
|
||||
__u32 used_len;
|
||||
__u16 len[LGUEST_MAX_DMA_SECTIONS];
|
||||
unsigned long addr[LGUEST_MAX_DMA_SECTIONS];
|
||||
};
|
||||
/*:*/
|
||||
|
||||
/* Where the Host expects the Guest to SEND_DMA console output to. */
|
||||
#define LGUEST_CONSOLE_DMA_KEY 0
|
||||
|
||||
|
|
@ -95,7 +61,7 @@ struct lguest_device_desc {
|
|||
enum lguest_req
|
||||
{
|
||||
LHREQ_INITIALIZE, /* + pfnlimit, pgdir, start, pageoffset */
|
||||
LHREQ_GETDMA, /* + addr (returns &lguest_dma, irq in ->used_len) */
|
||||
LHREQ_GETDMA, /* No longer used */
|
||||
LHREQ_IRQ, /* + irq */
|
||||
LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
|
||||
};
|
||||
|
|
|
|||
Loading…
Reference in a new issue