VMCB02 instruction bytes are valid only for the hardware VM-Exit that populated them. Track whether VMCB02 contains instruction bytes for the data #PF or #NPF currently being reflected to L1 so that stale bytes are not copied to VMCB12.
Clear the VMCB02 instruction-byte fields and freshness state before each nested run. Mark the bytes as fresh only when a data #PF or #NPF came from hardware; KVM-synthesized exits and instruction-fetch faults leave the state clear. A subsequent change will use this state when propagating hardware DecodeAssist instruction bytes to VMCB12. Signed-off-by: Tina Zhang <[email protected]> --- arch/x86/kvm/svm/nested.c | 41 +++++++++++++++++++++++++++++++++++++-- arch/x86/kvm/svm/svm.c | 6 +++--- arch/x86/kvm/svm/svm.h | 5 ++++- 3 files changed, 46 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 73f37b050d0a..6770721d4e4c 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -35,6 +35,38 @@ #define CC KVM_NESTED_VMENTER_CONSISTENCY_CHECK +static void nested_svm_clear_insn_bytes(struct vmcb *vmcb) +{ + vmcb->control.insn_len = 0; + memset(vmcb->control.insn_bytes, 0, + sizeof(vmcb->control.insn_bytes)); +} + +static bool nested_svm_vmexit_has_insn_bytes(const struct vmcb *vmcb) +{ + u64 exit_code = vmcb->control.exit_code; + + if (exit_code != SVM_EXIT_NPF && + exit_code != SVM_EXIT_EXCP_BASE + PF_VECTOR) + return false; + + return !(vmcb->control.exit_info_1 & PFERR_FETCH_MASK); +} + +static void nested_svm_set_vmcb02_insn_bytes_fresh(struct vcpu_svm *svm, + bool from_hardware) +{ + svm->nested.vmcb02_insn_bytes_fresh = + from_hardware && static_cpu_has(X86_FEATURE_DECODEASSISTS) && + nested_svm_vmexit_has_insn_bytes(svm->vmcb); +} + +static void nested_svm_clear_vmcb02_insn_bytes(struct vcpu_svm *svm) +{ + nested_svm_clear_insn_bytes(svm->nested.vmcb02.ptr); + 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) @@ -68,6 +100,7 @@ static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu, (fault->error_code & ~PFERR_GUEST_FAULT_STAGE_MASK); vmcb->control.exit_info_2 = fault->address; + nested_svm_set_vmcb02_insn_bytes_fresh(svm, from_hardware); nested_svm_vmexit(svm); } @@ -868,7 +901,9 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) /* * Filled at exit: exit_code, exit_info_1, exit_info_2, exit_int_info, * exit_int_info_err, next_rip, insn_len, insn_bytes. + * Clear stale DecodeAssist data before L2 runs. */ + nested_svm_clear_vmcb02_insn_bytes(svm); if (guest_cpu_cap_has(vcpu, X86_FEATURE_VGIF) && (vmcb12_ctrl->int_ctl & V_GIF_ENABLE_MASK)) @@ -1643,14 +1678,16 @@ static int nested_svm_intercept(struct vcpu_svm *svm) return vmexit; } -int nested_svm_exit_handled(struct vcpu_svm *svm) +int nested_svm_exit_handled(struct vcpu_svm *svm, bool from_hardware) { int vmexit; vmexit = nested_svm_intercept(svm); - if (vmexit == NESTED_EXIT_DONE) + if (vmexit == NESTED_EXIT_DONE) { + nested_svm_set_vmcb02_insn_bytes_fresh(svm, from_hardware); nested_svm_vmexit(svm); + } return vmexit; } diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index c7c1f1527c3c..5426a9669053 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2571,7 +2571,7 @@ static bool check_selective_cr0_intercepted(struct kvm_vcpu *vcpu, if (cr0 ^ val) { svm->vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE; - ret = (nested_svm_exit_handled(svm) == NESTED_EXIT_DONE); + ret = (nested_svm_exit_handled(svm, false) == NESTED_EXIT_DONE); } return ret; @@ -3723,7 +3723,7 @@ static int svm_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) vmexit = nested_svm_exit_special(svm); if (vmexit == NESTED_EXIT_CONTINUE) - vmexit = nested_svm_exit_handled(svm); + vmexit = nested_svm_exit_handled(svm, true); if (vmexit == NESTED_EXIT_DONE) return 1; @@ -4983,7 +4983,7 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, if (static_cpu_has(X86_FEATURE_NRIPS)) vmcb->control.next_rip = info->next_rip; vmcb->control.exit_code = icpt_info.exit_code; - vmexit = nested_svm_exit_handled(svm); + vmexit = nested_svm_exit_handled(svm, false); ret = (vmexit == NESTED_EXIT_DONE) ? X86EMUL_INTERCEPTED : X86EMUL_CONTINUE; diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 66b44b54608e..610def16f700 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -242,6 +242,9 @@ struct svm_nested_state { * on its side. */ bool force_msr_bitmap_recalc; + + /* True if VMCB02 has instruction bytes from the current hardware exit. */ + bool vmcb02_insn_bytes_fresh; }; struct vcpu_sev_es_state { @@ -887,7 +890,7 @@ static inline void nested_svm_simple_vmexit(struct vcpu_svm *svm, u32 exit_code) nested_svm_vmexit(svm); } -int nested_svm_exit_handled(struct vcpu_svm *svm); +int nested_svm_exit_handled(struct vcpu_svm *svm, bool from_hardware); int nested_svm_check_permissions(struct kvm_vcpu *vcpu); int nested_svm_check_cached_vmcb12(struct kvm_vcpu *vcpu); int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr, -- 2.43.7
