DecodeAssists provides instruction bytes for nested page faults and intercepted page faults caused by data accesses. When the feature is exposed to L1, copy fresh hardware-provided instruction bytes from VMCB02 to VMCB12 for these exits.
Clear the VMCB12 instruction-byte state before rebuilding it, and leave the length zero for instruction-fetch page faults, unrelated exits, and exits without fresh hardware bytes. Signed-off-by: Tina Zhang <[email protected]> --- arch/x86/kvm/svm/nested.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 6770721d4e4c..2db0ec66e8dc 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -42,6 +42,20 @@ static void nested_svm_clear_insn_bytes(struct vmcb *vmcb) sizeof(vmcb->control.insn_bytes)); } +static void nested_svm_copy_insn_bytes(struct vmcb *to, + const struct vmcb *from) +{ + u8 insn_len = from->control.insn_len; + + nested_svm_clear_insn_bytes(to); + + if (WARN_ON_ONCE(insn_len > sizeof(from->control.insn_bytes))) + return; + + to->control.insn_len = insn_len; + memcpy(to->control.insn_bytes, from->control.insn_bytes, insn_len); +} + static bool nested_svm_vmexit_has_insn_bytes(const struct vmcb *vmcb) { u64 exit_code = vmcb->control.exit_code; @@ -67,6 +81,25 @@ static void nested_svm_clear_vmcb02_insn_bytes(struct vcpu_svm *svm) svm->nested.vmcb02_insn_bytes_fresh = false; } +static void nested_svm_update_vmcb12_insn_bytes(struct kvm_vcpu *vcpu, + struct vmcb *vmcb12, + const struct vmcb *vmcb02) +{ + struct vcpu_svm *svm = to_svm(vcpu); + + nested_svm_clear_insn_bytes(vmcb12); + + if (!guest_cpu_cap_has(vcpu, X86_FEATURE_DECODEASSISTS) || + !nested_svm_vmexit_has_insn_bytes(vmcb02)) + goto out; + + if (svm->nested.vmcb02_insn_bytes_fresh) + nested_svm_copy_insn_bytes(vmcb12, vmcb02); + +out: + svm->nested.vmcb02_insn_bytes_fresh = false; +} + static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu, struct x86_exception *fault, bool from_hardware) @@ -1332,6 +1365,8 @@ static int nested_svm_vmexit_update_vmcb12(struct kvm_vcpu *vcpu) if (guest_cpu_cap_has(vcpu, X86_FEATURE_NRIPS)) vmcb12->control.next_rip = vmcb02->control.next_rip; + nested_svm_update_vmcb12_insn_bytes(vcpu, vmcb12, vmcb02); + if (nested_vmcb12_has_lbrv(vcpu)) svm_copy_lbrs(&vmcb12->save, &vmcb02->save); -- 2.43.7
