lguest.h
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/* Things the lguest guest needs to know. Note: like all lguest interfaces,
* this is subject to wild and random change between versions. */
#ifndef _ASM_LGUEST_H
#define _ASM_LGUEST_H
#ifndef __ASSEMBLY__
#include <asm/irq.h>
#define LHCALL_FLUSH_ASYNC 0
#define LHCALL_LGUEST_INIT 1
#define LHCALL_CRASH 2
#define LHCALL_LOAD_GDT 3
#define LHCALL_NEW_PGTABLE 4
#define LHCALL_FLUSH_TLB 5
#define LHCALL_LOAD_IDT_ENTRY 6
#define LHCALL_SET_STACK 7
#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 LG_CLOCK_MIN_DELTA 100UL
#define LG_CLOCK_MAX_DELTA ULONG_MAX
/*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",
* to make requests of the Host Itself.
*
* Our hypercall mechanism uses the highest unused trap code (traps 32 and
* above are used by real hardware interrupts). Seventeen hypercalls are
* available: the hypercall number is put in the %eax register, and the
* arguments (when required) are placed in %edx, %ebx and %ecx. If a return
* value makes sense, it's returned in %eax.
*
* Grossly invalid calls result in Sudden Death at the hands of the vengeful
* Host, rather than returning failure. This reflects Winston Churchill's
* definition of a gentleman: "someone who is only rude intentionally". */
#define LGUEST_TRAP_ENTRY 0x1F
static inline unsigned long
hcall(unsigned long call,
unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
/* "int" is the Intel instruction to trigger a trap. */
asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
/* The call is in %eax (aka "a"), and can be replaced */
: "=a"(call)
/* The other arguments are in %eax, %edx, %ebx & %ecx */
: "a"(call), "d"(arg1), "b"(arg2), "c"(arg3)
/* "memory" means this might write somewhere in memory.
* This isn't true for all calls, but it's safe to tell
* gcc that it might happen so it doesn't get clever. */
: "memory");
return call;
}
/*:*/
void async_hcall(unsigned long call,
unsigned long arg1, unsigned long arg2, unsigned long arg3);
/* Can't use our min() macro here: needs to be a constant */
#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
#define LHCALL_RING_SIZE 64
struct hcall_ring
{
u32 eax, edx, ebx, ecx;
};
/*G:032 The second method of communicating with the Host is to via "struct
* lguest_data". The Guest's very first hypercall is to tell the Host where
* this is, and then the Guest and Host both publish information in it. :*/
struct lguest_data
{
/* 512 == enabled (same as eflags in normal hardware). The Guest
* changes interrupts so often that a hypercall is too slow. */
unsigned int irq_enabled;
/* Fine-grained interrupt disabling by the Guest */
DECLARE_BITMAP(blocked_interrupts, LGUEST_IRQS);
/* The Host writes the virtual address of the last page fault here,
* which saves the Guest a hypercall. CR2 is the native register where
* this address would normally be found. */
unsigned long cr2;
/* Wallclock time set by the Host. */
struct timespec time;
/* Async hypercall ring. Instead of directly making hypercalls, we can
* place them in here for processing the next time the Host wants.
* This batching can be quite efficient. */
/* 0xFF == done (set by Host), 0 == pending (set by Guest). */
u8 hcall_status[LHCALL_RING_SIZE];
/* The actual registers for the hypercalls. */
struct hcall_ring hcalls[LHCALL_RING_SIZE];
/* Fields initialized by the Host at boot: */
/* Memory not to try to access */
unsigned long reserve_mem;
/* ID of this Guest (used by network driver to set ethernet address) */
u16 guestid;
/* KHz for the TSC clock. */
u32 tsc_khz;
/* Fields initialized by the Guest at boot: */
/* Instruction range to suppress interrupts even if enabled */
unsigned long noirq_start, noirq_end;
};
extern struct lguest_data lguest_data;
#endif /* __ASSEMBLY__ */
#endif /* _ASM_LGUEST_H */