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Inject page fault into the guest if the page table walker detects an invalid

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translation for the guest linear address.
This commit is contained in:
neel 2014-05-22 03:14:54 +00:00
parent 9e29b5f650
commit 645d479a58
4 changed files with 82 additions and 25 deletions
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1
sys/amd64/include/vmm.h
View File

@ -236,6 +236,7 @@ int vm_exception_pending(struct vm *vm, int vcpuid, struct vm_exception *vme);
void vm_inject_gp(struct vm *vm, int vcpuid); /* general protection fault */
void vm_inject_ud(struct vm *vm, int vcpuid); /* undefined instruction fault */
void vm_inject_pf(struct vm *vm, int vcpuid, int error_code); /* page fault */
#endif /* KERNEL */

10
sys/amd64/include/vmm_instruction_emul.h
View File

@ -122,6 +122,16 @@ int vmm_fetch_instruction(struct vm *vm, int cpuid,
enum vie_paging_mode paging_mode, int cpl,
struct vie *vie);
/*
* Translate the guest linear address 'gla' to a guest physical address.
*
* Returns 0 on success and '*gpa' contains the result of the translation.
* Returns 1 if a page fault exception was injected into the guest.
* Returns -1 otherwise.
*/
int vmm_gla2gpa(struct vm *vm, int vcpuid, uint64_t gla, uint64_t cr3,
uint64_t *gpa, enum vie_paging_mode paging_mode, int cpl, int prot);
void vie_init(struct vie *vie);
/*

21
sys/amd64/vmm/vmm.c
View File

@ -1155,9 +1155,14 @@ vm_handle_inst_emul(struct vm *vm, int vcpuid, bool *retu)
vie_init(vie);
/* Fetch, decode and emulate the faulting instruction */
if (vmm_fetch_instruction(vm, vcpuid, rip, inst_length, cr3,
paging_mode, cpl, vie) != 0)
error = vmm_fetch_instruction(vm, vcpuid, rip, inst_length, cr3,
paging_mode, cpl, vie);
if (error == 1)
return (0); /* Resume guest to handle page fault */
else if (error == -1)
return (EFAULT);
else if (error != 0)
panic("%s: vmm_fetch_instruction error %d", __func__, error);
if (vmm_decode_instruction(vm, vcpuid, gla, cpu_mode, vie) != 0)
return (EFAULT);
@ -1430,6 +1435,18 @@ vm_inject_fault(struct vm *vm, int vcpuid, struct vm_exception *exception)
vmexit->inst_length = 0;
}
void
vm_inject_pf(struct vm *vm, int vcpuid, int error_code)
{
struct vm_exception pf = {
.vector = IDT_PF,
.error_code_valid = 1,
.error_code = error_code
};
vm_inject_fault(vm, vcpuid, &pf);
}
void
vm_inject_gp(struct vm *vm, int vcpuid)
{

75
sys/amd64/vmm/vmm_instruction_emul.c
View File

@ -572,6 +572,23 @@ vie_init(struct vie *vie)
vie->index_register = VM_REG_LAST;
}
static int
pf_error_code(int usermode, int prot, uint64_t pte)
{
int error_code = 0;
if (pte & PG_V)
error_code |= PGEX_P;
if (prot & VM_PROT_WRITE)
error_code |= PGEX_W;
if (usermode)
error_code |= PGEX_U;
if (prot & VM_PROT_EXECUTE)
error_code |= PGEX_I;
return (error_code);
}
static void
ptp_release(void **cookie)
{
@ -591,11 +608,11 @@ ptp_hold(struct vm *vm, vm_paddr_t ptpphys, size_t len, void **cookie)
return (ptr);
}
static int
gla2gpa(struct vm *vm, uint64_t gla, uint64_t ptpphys, uint64_t *gpa,
enum vie_paging_mode paging_mode, int cpl, int prot)
int
vmm_gla2gpa(struct vm *vm, int vcpuid, uint64_t gla, uint64_t ptpphys,
uint64_t *gpa, enum vie_paging_mode paging_mode, int cpl, int prot)
{
int nlevels, ptpshift, ptpindex, retval, usermode, writable;
int nlevels, pfcode, ptpshift, ptpindex, retval, usermode, writable;
u_int retries;
uint64_t *ptpbase, pte, pgsize;
uint32_t *ptpbase32, pte32;
@ -604,7 +621,7 @@ gla2gpa(struct vm *vm, uint64_t gla, uint64_t ptpphys, uint64_t *gpa,
usermode = (cpl == 3 ? 1 : 0);
writable = prot & VM_PROT_WRITE;
cookie = NULL;
retval = -1;
retval = 0;
retries = 0;
restart:
ptp_release(&cookie);
@ -633,11 +650,13 @@ restart:
pte32 = ptpbase32[ptpindex];
if ((pte32 & PG_V) == 0)
goto error;
if (usermode && (pte32 & PG_U) == 0)
goto error;
if ((pte32 & PG_V) == 0 ||
(usermode && (pte32 & PG_U) == 0) ||
(writable && (pte32 & PG_RW) == 0)) {
pfcode = pf_error_code(usermode, prot, pte32);
vm_inject_pf(vm, vcpuid, pfcode);
goto pagefault;
}
if (writable && (pte32 & PG_RW) == 0)
goto error;
@ -689,8 +708,11 @@ restart:
pte = ptpbase[ptpindex];
if ((pte & PG_V) == 0)
goto error;
if ((pte & PG_V) == 0) {
pfcode = pf_error_code(usermode, prot, pte);
vm_inject_pf(vm, vcpuid, pfcode);
goto pagefault;
}
ptpphys = pte;
@ -711,11 +733,13 @@ restart:
pte = ptpbase[ptpindex];
if ((pte & PG_V) == 0)
goto error;
if (usermode && (pte & PG_U) == 0)
goto error;
if ((pte & PG_V) == 0 ||
(usermode && (pte & PG_U) == 0) ||
(writable && (pte & PG_RW) == 0)) {
pfcode = pf_error_code(usermode, prot, pte);
vm_inject_pf(vm, vcpuid, pfcode);
goto pagefault;
}
if (writable && (pte & PG_RW) == 0)
goto error;
@ -748,10 +772,14 @@ restart:
pte >>= ptpshift; pte <<= (ptpshift + 12); pte >>= 12;
*gpa = pte | (gla & (pgsize - 1));
done:
retval = 0;
error:
ptp_release(&cookie);
return (retval);
error:
retval = -1;
goto done;
pagefault:
retval = 1;
goto done;
}
int
@ -759,7 +787,7 @@ vmm_fetch_instruction(struct vm *vm, int cpuid, uint64_t rip, int inst_length,
uint64_t cr3, enum vie_paging_mode paging_mode, int cpl,
struct vie *vie)
{
int n, err, prot;
int n, error, prot;
uint64_t gpa, off;
void *hpa, *cookie;
@ -773,9 +801,10 @@ vmm_fetch_instruction(struct vm *vm, int cpuid, uint64_t rip, int inst_length,
/* Copy the instruction into 'vie' */
while (vie->num_valid < inst_length) {
err = gla2gpa(vm, rip, cr3, &gpa, paging_mode, cpl, prot);
if (err)
break;
error = vmm_gla2gpa(vm, cpuid, rip, cr3, &gpa, paging_mode,
cpl, prot);
if (error)
return (error);
off = gpa & PAGE_MASK;
n = min(inst_length - vie->num_valid, PAGE_SIZE - off);