From 1aa561b1a4c0ae2a9a9b9c21a84b5ca66b4775d8 Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Wed, 3 Jun 2020 16:56:21 -0700 Subject: [PATCH] kvm: x86: Add "last CPU" to some KVM_EXIT information More often than not, a failed VM-entry in an x86 production environment is induced by a defective CPU. To help identify the bad hardware, include the id of the last logical CPU to run a vCPU in the information provided to userspace on a KVM exit for failed VM-entry or for KVM internal errors not associated with emulation. The presence of this additional information is indicated by a new capability, KVM_CAP_LAST_CPU. Signed-off-by: Jim Mattson Reviewed-by: Oliver Upton Reviewed-by: Peter Shier Message-Id: <20200603235623.245638-5-jmattson@google.com> Signed-off-by: Paolo Bonzini --- Documentation/virt/kvm/api.rst | 1 + arch/x86/kvm/svm/svm.c | 4 +++- arch/x86/kvm/vmx/vmx.c | 10 ++++++++-- arch/x86/kvm/x86.c | 1 + include/uapi/linux/kvm.h | 2 ++ 5 files changed, 15 insertions(+), 3 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 426f945..1cfe79b 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -4794,6 +4794,7 @@ hardware_exit_reason. /* KVM_EXIT_FAIL_ENTRY */ struct { __u64 hardware_entry_failure_reason; + __u32 cpu; /* if KVM_LAST_CPU */ } fail_entry; If exit_reason is KVM_EXIT_FAIL_ENTRY, the vcpu could not be run due diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 24b7f32..8ecd46f 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2947,6 +2947,7 @@ static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY; kvm_run->fail_entry.hardware_entry_failure_reason = svm->vmcb->control.exit_code; + kvm_run->fail_entry.cpu = svm->last_cpu; dump_vmcb(vcpu); return 0; } @@ -2970,8 +2971,9 @@ static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON; - vcpu->run->internal.ndata = 1; + vcpu->run->internal.ndata = 2; vcpu->run->internal.data[0] = exit_code; + vcpu->run->internal.data[1] = svm->last_cpu; return 0; } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 4d8f12c..b52bceb 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4781,10 +4781,11 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) !(is_page_fault(intr_info) && !(error_code & PFERR_RSVD_MASK))) { vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_SIMUL_EX; - vcpu->run->internal.ndata = 3; + vcpu->run->internal.ndata = 4; vcpu->run->internal.data[0] = vect_info; vcpu->run->internal.data[1] = intr_info; vcpu->run->internal.data[2] = error_code; + vcpu->run->internal.data[3] = vmx->last_cpu; return 0; } @@ -6006,6 +6007,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY; vcpu->run->fail_entry.hardware_entry_failure_reason = exit_reason; + vcpu->run->fail_entry.cpu = vmx->last_cpu; return 0; } @@ -6014,6 +6016,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY; vcpu->run->fail_entry.hardware_entry_failure_reason = vmcs_read32(VM_INSTRUCTION_ERROR); + vcpu->run->fail_entry.cpu = vmx->last_cpu; return 0; } @@ -6040,6 +6043,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) vcpu->run->internal.data[3] = vmcs_read64(GUEST_PHYSICAL_ADDRESS); } + vcpu->run->internal.data[vcpu->run->internal.ndata++] = + vmx->last_cpu; return 0; } @@ -6095,8 +6100,9 @@ unexpected_vmexit: vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON; - vcpu->run->internal.ndata = 1; + vcpu->run->internal.ndata = 2; vcpu->run->internal.data[0] = exit_reason; + vcpu->run->internal.data[1] = vmx->last_cpu; return 0; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 82f457f..1a0fad1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3510,6 +3510,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_MSR_PLATFORM_INFO: case KVM_CAP_EXCEPTION_PAYLOAD: case KVM_CAP_SET_GUEST_DEBUG: + case KVM_CAP_LAST_CPU: r = 1; break; case KVM_CAP_SYNC_REGS: diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4fdf303..ff9b335 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -289,6 +289,7 @@ struct kvm_run { /* KVM_EXIT_FAIL_ENTRY */ struct { __u64 hardware_entry_failure_reason; + __u32 cpu; } fail_entry; /* KVM_EXIT_EXCEPTION */ struct { @@ -1031,6 +1032,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_PPC_SECURE_GUEST 181 #define KVM_CAP_HALT_POLL 182 #define KVM_CAP_ASYNC_PF_INT 183 +#define KVM_CAP_LAST_CPU 184 #ifdef KVM_CAP_IRQ_ROUTING -- 2.7.4