On Fri, Dec 13, 2019 at 3:26 PM Liran Alon <liran.alon@xxxxxxxxxx> wrote:
>
>
>
> > On 14 Dec 2019, at 1:16, Jim Mattson <jmattson@xxxxxxxxxx> wrote:
> >
> > More often than not, a failed VM-entry in a production environment is
> > the result of a defective CPU (at least, insofar as Intel x86 is
> > concerned). To aid in identifying the bad hardware, add the logical
> > CPU to the information provided to userspace on a KVM exit with reason
> > KVM_EXIT_FAIL_ENTRY. The presence of this additional information is
> > indicated by a new capability, KVM_CAP_FAILED_ENTRY_CPU.
> >
> > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> > Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
> > Reviewed-by: Oliver Upton <oupton@xxxxxxxxxx>
> > ---
> > Documentation/virt/kvm/api.txt | 1 +
> > arch/x86/kvm/svm.c | 1 +
> > arch/x86/kvm/vmx/vmx.c | 2 ++
> > arch/x86/kvm/x86.c | 1 +
> > include/uapi/linux/kvm.h | 2 ++
> > 5 files changed, 7 insertions(+)
> >
> > diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
> > index ebb37b34dcfc..6e5d92406b65 100644
> > --- a/Documentation/virt/kvm/api.txt
> > +++ b/Documentation/virt/kvm/api.txt
> > @@ -4245,6 +4245,7 @@ hardware_exit_reason.
> > /* KVM_EXIT_FAIL_ENTRY */
> > struct {
> > __u64 hardware_entry_failure_reason;
> > + __u32 cpu; /* if KVM_CAP_FAILED_ENTRY_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.c b/arch/x86/kvm/svm.c
> > index 122d4ce3b1ab..4d06b2413c63 100644
> > --- a/arch/x86/kvm/svm.c
> > +++ b/arch/x86/kvm/svm.c
> > @@ -4980,6 +4980,7 @@ static int handle_exit(struct kvm_vcpu *vcpu)
> > 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 = raw_smp_processor_id();
>
> Why not just use vcpu->cpu?
> Same for vmx_handle_exit() to be consistent.
Ah. Perfect. Thanks.
> > dump_vmcb(vcpu);
> > return 0;
> > }
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index e3394c839dea..4d540b1c08e0 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -5846,6 +5846,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
> > vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY;
> > vcpu->run->fail_entry.hardware_entry_failure_reason
> > = exit_reason;
> > + vcpu->run->fail_entry.cpu = vmx->loaded_vmcs->cpu;
> > return 0;
> > }
> >
> > @@ -5854,6 +5855,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
> > 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->loaded_vmcs->cpu;
> > return 0;
> > }
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index cf917139de6b..9e89a32056d1 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -3273,6 +3273,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> > case KVM_CAP_GET_MSR_FEATURES:
> > case KVM_CAP_MSR_PLATFORM_INFO:
> > case KVM_CAP_EXCEPTION_PAYLOAD:
> > + case KVM_CAP_FAILED_ENTRY_CPU:
> > r = 1;
> > break;
> > case KVM_CAP_SYNC_REGS:
> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index f0a16b4adbbd..09ba7174456d 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -277,6 +277,7 @@ struct kvm_run {
> > /* KVM_EXIT_FAIL_ENTRY */
> > struct {
> > __u64 hardware_entry_failure_reason;
> > + __u32 cpu;
> > } fail_entry;
> > /* KVM_EXIT_EXCEPTION */
> > struct {
> > @@ -1009,6 +1010,7 @@ struct kvm_ppc_resize_hpt {
> > #define KVM_CAP_PPC_GUEST_DEBUG_SSTEP 176
> > #define KVM_CAP_ARM_NISV_TO_USER 177
> > #define KVM_CAP_ARM_INJECT_EXT_DABT 178
> > +#define KVM_CAP_FAILED_ENTRY_CPU 179
> >
> > #ifdef KVM_CAP_IRQ_ROUTING
> >
> > --
> > 2.24.1.735.g03f4e72817-goog
> >
>
