From: Andre Przywara <andre.przywara@xxxxxxx>
In case of a nested page fault or an intercepted #PF newer SVM
implementations provide a copy of the faulting instruction bytes
in the VMCB.
Use these bytes to feed the instruction emulator and avoid the costly
guest instruction fetch in this case.
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index bf70ece..8e37deb 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -265,7 +265,7 @@ struct x86_emulate_ctxt {
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
#endif
-int x86_decode_insn(struct x86_emulate_ctxt *ctxt);
+int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len);
#define EMULATION_FAILED -1
#define EMULATION_OK 0
#define EMULATION_RESTART 1
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index de00b60..6268f6c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -634,13 +634,13 @@ enum emulation_result {
#define EMULTYPE_NO_DECODE (1 << 0)
#define EMULTYPE_TRAP_UD (1 << 1)
#define EMULTYPE_SKIP (1 << 2)
-int x86_emulate_instruction(struct kvm_vcpu *vcpu,
- unsigned long cr2, int emulation_type);
+int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
+ int emulation_type, void *insn, int insn_len);
static inline int emulate_instruction(struct kvm_vcpu *vcpu,
int emulation_type)
{
- return x86_emulate_instruction(vcpu, 0, emulation_type);
+ return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);
}
void realmode_lgdt(struct kvm_vcpu *vcpu, u16 size, unsigned long address);
@@ -721,7 +721,8 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
int kvm_fix_hypercall(struct kvm_vcpu *vcpu);
-int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code);
+int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code,
+ void *insn, int insn_len);
void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
void kvm_enable_tdp(void);
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index f0ffb81..f2b83bc 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -83,7 +83,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
u32 clean;
u32 reserved_5;
u64 next_rip;
- u8 reserved_6[816];
+ u8 insn_len;
+ u8 insn_bytes[15];
+ u8 reserved_6[800];
};
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 6366735..02a0041 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2610,7 +2610,7 @@ done:
}
int
-x86_decode_insn(struct x86_emulate_ctxt *ctxt)
+x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
{
struct x86_emulate_ops *ops = ctxt->ops;
struct decode_cache *c = &ctxt->decode;
@@ -2621,7 +2621,10 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt)
struct operand memop = { .type = OP_NONE };
c->eip = ctxt->eip;
- c->fetch.start = c->fetch.end = c->eip;
+ c->fetch.start = c->eip;
+ c->fetch.end = c->fetch.start + insn_len;
+ if (insn_len > 0)
+ memcpy(c->fetch.data, insn, insn_len);
ctxt->cs_base = seg_base(ctxt, ops, VCPU_SREG_CS);
switch (mode) {
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 75334de..397a98f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3329,7 +3329,8 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
}
}
-int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
+int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code,
+ void *insn, int insn_len)
{
int r;
enum emulation_result er;
@@ -3347,7 +3348,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
if (r)
goto out;
- er = x86_emulate_instruction(vcpu, cr2, 0);
+ er = x86_emulate_instruction(vcpu, cr2, 0, insn, insn_len);
switch (er) {
case EMULATE_DONE:
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7b7e1ab..c9d711f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1527,7 +1527,9 @@ static int pf_interception(struct vcpu_svm *svm)
trace_kvm_page_fault(fault_address, error_code);
if (!npt_enabled && kvm_event_needs_reinjection(&svm->vcpu))
kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address);
- r = kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code);
+ r = kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code,
+ svm->vmcb->control.insn_bytes,
+ svm->vmcb->control.insn_len);
break;
case KVM_PV_REASON_PAGE_NOT_PRESENT:
svm->apf_reason = 0;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f3c60fb..736f839 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3055,7 +3055,7 @@ static int handle_exception(struct kvm_vcpu *vcpu)
if (kvm_event_needs_reinjection(vcpu))
kvm_mmu_unprotect_page_virt(vcpu, cr2);
- return kvm_mmu_page_fault(vcpu, cr2, error_code);
+ return kvm_mmu_page_fault(vcpu, cr2, error_code, NULL, 0);
}
if (vmx->rmode.vm86_active &&
@@ -3502,7 +3502,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
trace_kvm_page_fault(gpa, exit_qualification);
- return kvm_mmu_page_fault(vcpu, gpa, exit_qualification & 0x3);
+ return kvm_mmu_page_fault(vcpu, gpa, exit_qualification & 0x3, NULL, 0);
}
static u64 ept_rsvd_mask(u64 spte, int level)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a6fcb76..7ad9cda 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4365,7 +4365,9 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gva_t gva)
int x86_emulate_instruction(struct kvm_vcpu *vcpu,
unsigned long cr2,
- int emulation_type)
+ int emulation_type,
+ void *insn,
+ int insn_len)
{
int r;
struct decode_cache *c = &vcpu->arch.emulate_ctxt.decode;
@@ -4386,7 +4388,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
vcpu->arch.emulate_ctxt.have_exception = false;
vcpu->arch.emulate_ctxt.perm_ok = false;
- r = x86_decode_insn(&vcpu->arch.emulate_ctxt);
+ r = x86_decode_insn(&vcpu->arch.emulate_ctxt, insn, insn_len);
if (r == X86EMUL_PROPAGATE_FAULT)
goto done;
--
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