This allows exceptions injected by the emulator to be properly delivered as vmexits. The code also becomes simpler, because we can just let all L0-intercepted exceptions go through the usual path. In particular, our emulation of the VMX #DB exit qualification is very much simplified, because the vmexit injection path can use kvm_deliver_exception_payload to update DR6.
Signed-off-by: Paolo Bonzini <[email protected]> --- arch/x86/kvm/svm/nested.c | 129 ++++++++++++++------------------------ arch/x86/kvm/svm/svm.c | 9 --- arch/x86/kvm/svm/svm.h | 1 + 3 files changed, 47 insertions(+), 92 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index e98ce5f6d562..35ce3bef0a9a 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -111,6 +111,8 @@ void recalc_intercepts(struct vcpu_svm *svm) h = &svm->nested.hsave->control; g = &svm->nested; + svm->nested.host_intercept_exceptions = h->intercept_exceptions; + c->intercept_cr = h->intercept_cr; c->intercept_dr = h->intercept_dr; c->intercept_exceptions = h->intercept_exceptions; @@ -625,50 +627,6 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm) return (value & mask) ? NESTED_EXIT_DONE : NESTED_EXIT_HOST; } -/* DB exceptions for our internal use must not cause vmexit */ -static int nested_svm_intercept_db(struct vcpu_svm *svm) -{ - unsigned long dr6 = svm->vmcb->save.dr6; - - /* Always catch it and pass it to userspace if debugging. */ - if (svm->vcpu.guest_debug & - (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) - return NESTED_EXIT_HOST; - - /* if we're not singlestepping, it's not ours */ - if (!svm->nmi_singlestep) - goto reflected_db; - - /* if it's not a singlestep exception, it's not ours */ - if (!(dr6 & DR6_BS)) - goto reflected_db; - - /* if the guest is singlestepping, it should get the vmexit */ - if (svm->nmi_singlestep_guest_rflags & X86_EFLAGS_TF) { - disable_nmi_singlestep(svm); - goto reflected_db; - } - - /* it's ours, the nested hypervisor must not see this one */ - return NESTED_EXIT_HOST; - -reflected_db: - /* - * Synchronize guest DR6 here just like in kvm_deliver_exception_payload; - * it will be moved into the nested VMCB by nested_svm_vmexit. Once - * exceptions will be moved to svm_check_nested_events, all this stuff - * will just go away and we could just return NESTED_EXIT_HOST - * unconditionally. db_interception will queue the exception, which - * will be processed by svm_check_nested_events if a nested vmexit is - * required, and we will just use kvm_deliver_exception_payload to copy - * the payload to DR6 before vmexit. - */ - WARN_ON(svm->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT); - svm->vcpu.arch.dr6 &= ~(DR_TRAP_BITS | DR6_RTM); - svm->vcpu.arch.dr6 |= dr6 & ~DR6_FIXED_1; - return NESTED_EXIT_DONE; -} - static int nested_svm_intercept_ioio(struct vcpu_svm *svm) { unsigned port, size, iopm_len; @@ -719,20 +677,12 @@ static int nested_svm_intercept(struct vcpu_svm *svm) break; } case SVM_EXIT_EXCP_BASE ... SVM_EXIT_EXCP_BASE + 0x1f: { - u32 excp_bits = 1 << (exit_code - SVM_EXIT_EXCP_BASE); - if (svm->nested.intercept_exceptions & excp_bits) { - if (exit_code == SVM_EXIT_EXCP_BASE + DB_VECTOR) - vmexit = nested_svm_intercept_db(svm); - else if (exit_code == SVM_EXIT_EXCP_BASE + BP_VECTOR && - svm->vcpu.guest_debug & KVM_GUESTDBG_USE_SW_BP) - vmexit = NESTED_EXIT_HOST; - else - vmexit = NESTED_EXIT_DONE; - } - /* async page fault always cause vmexit */ - else if ((exit_code == SVM_EXIT_EXCP_BASE + PF_VECTOR) && - svm->vcpu.arch.exception.nested_apf != 0) - vmexit = NESTED_EXIT_DONE; + /* + * Host-intercepted exceptions have been checked already in + * nested_svm_exit_special. There is nothing to do here, + * the vmexit is injected by svm_check_nested_events. + */ + vmexit = NESTED_EXIT_DONE; break; } case SVM_EXIT_ERR: { @@ -777,35 +727,38 @@ int nested_svm_check_permissions(struct vcpu_svm *svm) return 0; } -int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr, - bool has_error_code, u32 error_code) +static bool nested_exit_on_exception(struct vcpu_svm *svm) { - int vmexit; + unsigned int nr = svm->vcpu.arch.exception.nr; - if (!is_guest_mode(&svm->vcpu)) - return 0; + return (svm->nested.intercept_exceptions & (1 << nr)); +} - vmexit = nested_svm_intercept(svm); - if (vmexit != NESTED_EXIT_DONE) - return 0; +static void nested_svm_inject_exception_vmexit(struct vcpu_svm *svm) +{ + unsigned int nr = svm->vcpu.arch.exception.nr; svm->vmcb->control.exit_code = SVM_EXIT_EXCP_BASE + nr; svm->vmcb->control.exit_code_hi = 0; - svm->vmcb->control.exit_info_1 = error_code; + + if (svm->vcpu.arch.exception.has_error_code) + svm->vmcb->control.exit_info_1 = svm->vcpu.arch.exception.error_code; /* * EXITINFO2 is undefined for all exception intercepts other * than #PF. */ - if (svm->vcpu.arch.exception.nested_apf) - svm->vmcb->control.exit_info_2 = svm->vcpu.arch.apf.nested_apf_token; - else if (svm->vcpu.arch.exception.has_payload) - svm->vmcb->control.exit_info_2 = svm->vcpu.arch.exception.payload; - else - svm->vmcb->control.exit_info_2 = svm->vcpu.arch.cr2; + if (nr == PF_VECTOR) { + if (svm->vcpu.arch.exception.nested_apf) + svm->vmcb->control.exit_info_2 = svm->vcpu.arch.apf.nested_apf_token; + else if (svm->vcpu.arch.exception.has_payload) + svm->vmcb->control.exit_info_2 = svm->vcpu.arch.exception.payload; + else + svm->vmcb->control.exit_info_2 = svm->vcpu.arch.cr2; + } else if (svm->vcpu.arch.exception.has_payload) + kvm_deliver_exception_payload(&svm->vcpu); - svm->nested.exit_required = true; - return vmexit; + nested_svm_vmexit(svm); } static void nested_svm_smi(struct vcpu_svm *svm) @@ -844,6 +797,15 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu) kvm_event_needs_reinjection(vcpu) || svm->nested.exit_required || svm->nested.nested_run_pending; + if (vcpu->arch.exception.pending) { + if (block_nested_events) + return -EBUSY; + if (!nested_exit_on_exception(svm)) + return 0; + nested_svm_inject_exception_vmexit(svm); + return 0; + } + if (vcpu->arch.smi_pending && !svm_smi_blocked(vcpu)) { if (block_nested_events) return -EBUSY; @@ -881,18 +843,19 @@ int nested_svm_exit_special(struct vcpu_svm *svm) switch (exit_code) { case SVM_EXIT_INTR: case SVM_EXIT_NMI: - case SVM_EXIT_EXCP_BASE + MC_VECTOR: - return NESTED_EXIT_HOST; case SVM_EXIT_NPF: - /* For now we are always handling NPFs when using them */ - if (npt_enabled) + return NESTED_EXIT_HOST; + case SVM_EXIT_EXCP_BASE ... SVM_EXIT_EXCP_BASE + 0x1f: { + u32 excp_bits = 1 << (exit_code - SVM_EXIT_EXCP_BASE); + + if (svm->nested.host_intercept_exceptions & excp_bits) return NESTED_EXIT_HOST; - break; - case SVM_EXIT_EXCP_BASE + PF_VECTOR: - /* Trap async PF even if not shadowing */ - if (!npt_enabled || svm->vcpu.arch.apf.host_apf_reason) + else if (exit_code == SVM_EXIT_EXCP_BASE + PF_VECTOR && + svm->vcpu.arch.apf.host_apf_reason) + /* Trap async PF even if not shadowing */ return NESTED_EXIT_HOST; break; + } default: break; } diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 95d16aa76ebb..851484abafe6 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -331,17 +331,8 @@ static void svm_queue_exception(struct kvm_vcpu *vcpu) struct vcpu_svm *svm = to_svm(vcpu); unsigned nr = vcpu->arch.exception.nr; bool has_error_code = vcpu->arch.exception.has_error_code; - bool reinject = vcpu->arch.exception.injected; u32 error_code = vcpu->arch.exception.error_code; - /* - * If we are within a nested VM we'd better #VMEXIT and let the guest - * handle the exception - */ - if (!reinject && - nested_svm_check_exception(svm, nr, has_error_code, error_code)) - return; - kvm_deliver_exception_payload(&svm->vcpu); if (nr == BP_VECTOR && !nrips) { diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 39706aa845f2..1fb23a2cdf8b 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -86,6 +86,7 @@ struct nested_state { u64 hsave_msr; u64 vm_cr_msr; u64 vmcb; + u32 host_intercept_exceptions; /* These are the merged vectors */ u32 *msrpm; -- 2.18.2
