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kernel-fxtec-pro1x/arch/powerpc/kernel/kvm.c
Alexander Graf 71ee8e34fe KVM: PPC: Introduce branch patching helper 
We will need to patch several instruction streams over to a different
code path, so we need a way to patch a single instruction with a branch
somewhere else.

This patch adds a helper to facilitate this patching.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:50:54 +02:00

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/*
* Copyright (C) 2010 SUSE Linux Products GmbH. All rights reserved.
*
* Authors:
* Alexander Graf <agraf@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/kvm_host.h>
#include <linux/init.h>
#include <linux/kvm_para.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <asm/reg.h>
#include <asm/kvm_ppc.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
#include <asm/disassemble.h>
#define KVM_MAGIC_PAGE (-4096L)
#define magic_var(x) KVM_MAGIC_PAGE + offsetof(struct kvm_vcpu_arch_shared, x)
#define KVM_INST_LWZ 0x80000000
#define KVM_INST_STW 0x90000000
#define KVM_INST_LD 0xe8000000
#define KVM_INST_STD 0xf8000000
#define KVM_INST_NOP 0x60000000
#define KVM_INST_B 0x48000000
#define KVM_INST_B_MASK 0x03ffffff
#define KVM_INST_B_MAX 0x01ffffff
#define KVM_MASK_RT 0x03e00000
#define KVM_INST_MFMSR 0x7c0000a6
#define KVM_INST_MFSPR_SPRG0 0x7c1042a6
#define KVM_INST_MFSPR_SPRG1 0x7c1142a6
#define KVM_INST_MFSPR_SPRG2 0x7c1242a6
#define KVM_INST_MFSPR_SPRG3 0x7c1342a6
#define KVM_INST_MFSPR_SRR0 0x7c1a02a6
#define KVM_INST_MFSPR_SRR1 0x7c1b02a6
#define KVM_INST_MFSPR_DAR 0x7c1302a6
#define KVM_INST_MFSPR_DSISR 0x7c1202a6
#define KVM_INST_MTSPR_SPRG0 0x7c1043a6
#define KVM_INST_MTSPR_SPRG1 0x7c1143a6
#define KVM_INST_MTSPR_SPRG2 0x7c1243a6
#define KVM_INST_MTSPR_SPRG3 0x7c1343a6
#define KVM_INST_MTSPR_SRR0 0x7c1a03a6
#define KVM_INST_MTSPR_SRR1 0x7c1b03a6
#define KVM_INST_MTSPR_DAR 0x7c1303a6
#define KVM_INST_MTSPR_DSISR 0x7c1203a6
#define KVM_INST_TLBSYNC 0x7c00046c
static bool kvm_patching_worked = true;
static char kvm_tmp[1024 * 1024];
static int kvm_tmp_index;
static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
{
*inst = new_inst;
flush_icache_range((ulong)inst, (ulong)inst + 4);
}
static void kvm_patch_ins_ld(u32 *inst, long addr, u32 rt)
{
#ifdef CONFIG_64BIT
kvm_patch_ins(inst, KVM_INST_LD | rt | (addr & 0x0000fffc));
#else
kvm_patch_ins(inst, KVM_INST_LWZ | rt | ((addr + 4) & 0x0000fffc));
#endif
}
static void kvm_patch_ins_lwz(u32 *inst, long addr, u32 rt)
{
kvm_patch_ins(inst, KVM_INST_LWZ | rt | (addr & 0x0000ffff));
}
static void kvm_patch_ins_std(u32 *inst, long addr, u32 rt)
{
#ifdef CONFIG_64BIT
kvm_patch_ins(inst, KVM_INST_STD | rt | (addr & 0x0000fffc));
#else
kvm_patch_ins(inst, KVM_INST_STW | rt | ((addr + 4) & 0x0000fffc));
#endif
}
static void kvm_patch_ins_stw(u32 *inst, long addr, u32 rt)
{
kvm_patch_ins(inst, KVM_INST_STW | rt | (addr & 0x0000fffc));
}
static void kvm_patch_ins_nop(u32 *inst)
{
kvm_patch_ins(inst, KVM_INST_NOP);
}
static void kvm_patch_ins_b(u32 *inst, int addr)
{
#ifdef CONFIG_RELOCATABLE
/* On relocatable kernels interrupts handlers and our code
can be in different regions, so we don't patch them */
extern u32 __end_interrupts;
if ((ulong)inst < (ulong)&__end_interrupts)
return;
#endif
kvm_patch_ins(inst, KVM_INST_B | (addr & KVM_INST_B_MASK));
}
static u32 *kvm_alloc(int len)
{
u32 *p;
if ((kvm_tmp_index + len) > ARRAY_SIZE(kvm_tmp)) {
printk(KERN_ERR "KVM: No more space (%d + %d)\n",
kvm_tmp_index, len);
kvm_patching_worked = false;
return NULL;
}
p = (void*)&kvm_tmp[kvm_tmp_index];
kvm_tmp_index += len;
return p;
}
static void kvm_map_magic_page(void *data)
{
kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE,
KVM_MAGIC_PAGE, /* Physical Address */
KVM_MAGIC_PAGE); /* Effective Address */
}
static void kvm_check_ins(u32 *inst)
{
u32 _inst = *inst;
u32 inst_no_rt = _inst & ~KVM_MASK_RT;
u32 inst_rt = _inst & KVM_MASK_RT;
switch (inst_no_rt) {
/* Loads */
case KVM_INST_MFMSR:
kvm_patch_ins_ld(inst, magic_var(msr), inst_rt);
break;
case KVM_INST_MFSPR_SPRG0:
kvm_patch_ins_ld(inst, magic_var(sprg0), inst_rt);
break;
case KVM_INST_MFSPR_SPRG1:
kvm_patch_ins_ld(inst, magic_var(sprg1), inst_rt);
break;
case KVM_INST_MFSPR_SPRG2:
kvm_patch_ins_ld(inst, magic_var(sprg2), inst_rt);
break;
case KVM_INST_MFSPR_SPRG3:
kvm_patch_ins_ld(inst, magic_var(sprg3), inst_rt);
break;
case KVM_INST_MFSPR_SRR0:
kvm_patch_ins_ld(inst, magic_var(srr0), inst_rt);
break;
case KVM_INST_MFSPR_SRR1:
kvm_patch_ins_ld(inst, magic_var(srr1), inst_rt);
break;
case KVM_INST_MFSPR_DAR:
kvm_patch_ins_ld(inst, magic_var(dar), inst_rt);
break;
case KVM_INST_MFSPR_DSISR:
kvm_patch_ins_lwz(inst, magic_var(dsisr), inst_rt);
break;
/* Stores */
case KVM_INST_MTSPR_SPRG0:
kvm_patch_ins_std(inst, magic_var(sprg0), inst_rt);
break;
case KVM_INST_MTSPR_SPRG1:
kvm_patch_ins_std(inst, magic_var(sprg1), inst_rt);
break;
case KVM_INST_MTSPR_SPRG2:
kvm_patch_ins_std(inst, magic_var(sprg2), inst_rt);
break;
case KVM_INST_MTSPR_SPRG3:
kvm_patch_ins_std(inst, magic_var(sprg3), inst_rt);
break;
case KVM_INST_MTSPR_SRR0:
kvm_patch_ins_std(inst, magic_var(srr0), inst_rt);
break;
case KVM_INST_MTSPR_SRR1:
kvm_patch_ins_std(inst, magic_var(srr1), inst_rt);
break;
case KVM_INST_MTSPR_DAR:
kvm_patch_ins_std(inst, magic_var(dar), inst_rt);
break;
case KVM_INST_MTSPR_DSISR:
kvm_patch_ins_stw(inst, magic_var(dsisr), inst_rt);
break;
/* Nops */
case KVM_INST_TLBSYNC:
kvm_patch_ins_nop(inst);
break;
}
switch (_inst) {
}
}
static void kvm_use_magic_page(void)
{
u32 *p;
u32 *start, *end;
u32 tmp;
/* Tell the host to map the magic page to -4096 on all CPUs */
on_each_cpu(kvm_map_magic_page, NULL, 1);
/* Quick self-test to see if the mapping works */
if (__get_user(tmp, (u32*)KVM_MAGIC_PAGE)) {
kvm_patching_worked = false;
return;
}
/* Now loop through all code and find instructions */
start = (void*)_stext;
end = (void*)_etext;
for (p = start; p < end; p++)
kvm_check_ins(p);
printk(KERN_INFO "KVM: Live patching for a fast VM %s\n",
kvm_patching_worked ? "worked" : "failed");
}
unsigned long kvm_hypercall(unsigned long *in,
unsigned long *out,
unsigned long nr)
{
unsigned long register r0 asm("r0");
unsigned long register r3 asm("r3") = in[0];
unsigned long register r4 asm("r4") = in[1];
unsigned long register r5 asm("r5") = in[2];
unsigned long register r6 asm("r6") = in[3];
unsigned long register r7 asm("r7") = in[4];
unsigned long register r8 asm("r8") = in[5];
unsigned long register r9 asm("r9") = in[6];
unsigned long register r10 asm("r10") = in[7];
unsigned long register r11 asm("r11") = nr;
unsigned long register r12 asm("r12");
asm volatile("bl kvm_hypercall_start"
: "=r"(r0), "=r"(r3), "=r"(r4), "=r"(r5), "=r"(r6),
"=r"(r7), "=r"(r8), "=r"(r9), "=r"(r10), "=r"(r11),
"=r"(r12)
: "r"(r3), "r"(r4), "r"(r5), "r"(r6), "r"(r7), "r"(r8),
"r"(r9), "r"(r10), "r"(r11)
: "memory", "cc", "xer", "ctr", "lr");
out[0] = r4;
out[1] = r5;
out[2] = r6;
out[3] = r7;
out[4] = r8;
out[5] = r9;
out[6] = r10;
out[7] = r11;
return r3;
}
EXPORT_SYMBOL_GPL(kvm_hypercall);
static int kvm_para_setup(void)
{
extern u32 kvm_hypercall_start;
struct device_node *hyper_node;
u32 *insts;
int len, i;
hyper_node = of_find_node_by_path("/hypervisor");
if (!hyper_node)
return -1;
insts = (u32*)of_get_property(hyper_node, "hcall-instructions", &len);
if (len % 4)
return -1;
if (len > (4 * 4))
return -1;
for (i = 0; i < (len / 4); i++)
kvm_patch_ins(&(&kvm_hypercall_start)[i], insts[i]);
return 0;
}
static __init void kvm_free_tmp(void)
{
unsigned long start, end;
start = (ulong)&kvm_tmp[kvm_tmp_index + (PAGE_SIZE - 1)] & PAGE_MASK;
end = (ulong)&kvm_tmp[ARRAY_SIZE(kvm_tmp)] & PAGE_MASK;
/* Free the tmp space we don't need */
for (; start < end; start += PAGE_SIZE) {
ClearPageReserved(virt_to_page(start));
init_page_count(virt_to_page(start));
free_page(start);
totalram_pages++;
}
}
static int __init kvm_guest_init(void)
{
if (!kvm_para_available())
goto free_tmp;
if (kvm_para_setup())
goto free_tmp;
if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE))
kvm_use_magic_page();
free_tmp:
kvm_free_tmp();
return 0;
}
postcore_initcall(kvm_guest_init);
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