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kvm: x86: Add "last CPU" to some KVM_EXIT information

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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@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Message-Id: <20200603235623.245638-5-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jim Mattson 2020-06-03 16:56:21 -07:00 committed by Paolo Bonzini
parent 80a1684c01
commit 1aa561b1a4
5 changed files with 15 additions and 3 deletions
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1
Documentation/virt/kvm/api.rst
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@ -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

4
arch/x86/kvm/svm/svm.c
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@ -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;
}

10
arch/x86/kvm/vmx/vmx.c
View File

@ -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;
}

1
arch/x86/kvm/x86.c
View File

@ -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:

2
include/uapi/linux/kvm.h
View File

@ -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