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 <jmattson@xxxxxxxxxx>
Reviewed-by: Oliver Upton <oupton@xxxxxxxxxx>
Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
---
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 d280af5345df..17db8b68c165 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4792,6 +4792,7 @@ 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 442dbb763639..938be4172bab 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2945,6 +2945,7 @@ 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;
}
@@ -2968,8 +2969,9 @@ 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 42856970d3b8..da5490b94704 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4758,10 +4758,11 @@ 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;
}
@@ -5983,6 +5984,7 @@ 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;
}
@@ -5991,6 +5993,7 @@ 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;
}
@@ -6017,6 +6020,8 @@ 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;
}
@@ -6072,8 +6077,9 @@ static int vmx_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_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 9e41b5135340..20c420a45847 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3472,6 +3472,7 @@ 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 6721eb563eda..3edbd44d85bf 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
--
2.27.0.rc2.251.g90737beb825-goog
