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Allow caller to skip 'guest linear address' validation when doing instruction

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decode. This is to accomodate hardware assist implementations that do not
provide the 'guest linear address' as part of nested page fault collateral.

Submitted by:	Anish Gupta (akgupt3 at gmail dot com)
This commit is contained in:
Neel Natu 2013-03-28 21:26:19 +00:00
parent bea2eefca4
commit 66f71b7d24
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=248855
2 changed files with 16 additions and 5 deletions
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12
sys/amd64/include/vmm_instruction_emul.h
View File

@ -107,6 +107,18 @@ int vmm_fetch_instruction(struct vm *vm, int cpuid,
uint64_t rip, int inst_length, uint64_t cr3,
struct vie *vie);
/*
* Decode the instruction fetched into 'vie' so it can be emulated.
*
* 'gla' is the guest linear address provided by the hardware assist
* that caused the nested page table fault. It is used to verify that
* the software instruction decoding is in agreement with the hardware.
*
* Some hardware assists do not provide the 'gla' to the hypervisor.
* To skip the 'gla' verification for this or any other reason pass
* in VIE_INVALID_GLA instead.
*/
#define VIE_INVALID_GLA (1UL << 63) /* a non-canonical address */
int vmm_decode_instruction(struct vm *vm, int cpuid,
uint64_t gla, struct vie *vie);
#endif /* _KERNEL */

9
sys/amd64/vmm/vmm_instruction_emul.c
View File

@ -790,18 +790,20 @@ decode_immediate(struct vie *vie)
return (0);
}
#define VERIFY_GLA
/*
* Verify that the 'guest linear address' provided as collateral of the nested
* page table fault matches with our instruction decoding.
*/
#ifdef VERIFY_GLA
static int
verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie)
{
int error;
uint64_t base, idx;
/* Skip 'gla' verification */
if (gla == VIE_INVALID_GLA)
return (0);
base = 0;
if (vie->base_register != VM_REG_LAST) {
error = vm_get_register(vm, cpuid, vie->base_register, &base);
@ -832,7 +834,6 @@ verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie)
return (0);
}
#endif /* VERIFY_GLA */
int
vmm_decode_instruction(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie)
@ -856,10 +857,8 @@ vmm_decode_instruction(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie)
if (decode_immediate(vie))
return (-1);
#ifdef VERIFY_GLA
if (verify_gla(vm, cpuid, gla, vie))
return (-1);
#endif
vie->decoded = 1; /* success */