5dea1c88ed
The Host used to create some page tables for the Guest to use at the
top of Guest memory; it would then tell the Guest where this was. In
particular, it created linear mappings for 0 and 0xC0000000 addresses
because lguest used to switch to its real page tables quite late in
boot.
However, since d50d8fe19 Linux initialized boot page tables in
head_32.S even before the "are we lguest?" boot jump. So, now we can
simplify things: the Host pagetable code assumes 1:1 linear mapping
until it first calls the LHCALL_NEW_PGTABLE hypercall, which we now do
before we reach C code.
This also means that the Host doesn't need to know anything about the
Guest's PAGE_OFFSET. (Non-Linux guests might not even have such a
thing).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
73 lines
2.2 KiB
C
73 lines
2.2 KiB
C
/*
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* Things the lguest guest needs to know. Note: like all lguest interfaces,
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* this is subject to wild and random change between versions.
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*/
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#ifndef _LINUX_LGUEST_H
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#define _LINUX_LGUEST_H
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#ifndef __ASSEMBLY__
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#include <linux/time.h>
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#include <asm/irq.h>
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#include <asm/lguest_hcall.h>
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#define LG_CLOCK_MIN_DELTA 100UL
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#define LG_CLOCK_MAX_DELTA ULONG_MAX
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/*G:031
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* The second method of communicating with the Host is to via "struct
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* lguest_data". Once the Guest's initialization hypercall tells the Host where
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* this is, the Guest and Host both publish information in it.
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:*/
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struct lguest_data {
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/*
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* 512 == enabled (same as eflags in normal hardware). The Guest
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* changes interrupts so often that a hypercall is too slow.
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*/
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unsigned int irq_enabled;
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/* Fine-grained interrupt disabling by the Guest */
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DECLARE_BITMAP(blocked_interrupts, LGUEST_IRQS);
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/*
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* The Host writes the virtual address of the last page fault here,
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* which saves the Guest a hypercall. CR2 is the native register where
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* this address would normally be found.
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*/
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unsigned long cr2;
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/* Wallclock time set by the Host. */
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struct timespec time;
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/*
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* Interrupt pending set by the Host. The Guest should do a hypercall
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* if it re-enables interrupts and sees this set (to X86_EFLAGS_IF).
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*/
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int irq_pending;
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/*
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* Async hypercall ring. Instead of directly making hypercalls, we can
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* place them in here for processing the next time the Host wants.
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* This batching can be quite efficient.
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*/
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/* 0xFF == done (set by Host), 0 == pending (set by Guest). */
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u8 hcall_status[LHCALL_RING_SIZE];
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/* The actual registers for the hypercalls. */
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struct hcall_args hcalls[LHCALL_RING_SIZE];
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/* Fields initialized by the Host at boot: */
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/* Memory not to try to access */
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unsigned long reserve_mem;
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/* KHz for the TSC clock. */
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u32 tsc_khz;
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/* Fields initialized by the Guest at boot: */
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/* Instruction range to suppress interrupts even if enabled */
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unsigned long noirq_start, noirq_end;
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/* Address above which page tables are all identical. */
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unsigned long kernel_address;
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/* The vector to try to use for system calls (0x40 or 0x80). */
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unsigned int syscall_vec;
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};
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extern struct lguest_data lguest_data;
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#endif /* __ASSEMBLY__ */
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#endif /* _LINUX_LGUEST_H */
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