For the triple fault sythesized by KVM, e.g. the RSM path or
nested_vmx_abort(), if KVM exits to userspace before the request is
serviced, userspace could migrate the VM and lose the triple fault.
Extend KVM_{G,S}ET_VCPU_EVENTS to support pending triple fault with a
new event KVM_VCPUEVENT_VALID_FAULT_FAULT so that userspace can save and
restore the triple fault event. This extension is guarded by a new KVM
capability KVM_CAP_TRIPLE_FAULT_EVENT.
Note that in the set_vcpu_events path, userspace is able to set/clear
the triple fault request through triple_fault.pending field.
Signed-off-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 8 ++++++++
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/include/uapi/asm/kvm.h | 6 +++++-
arch/x86/kvm/x86.c | 21 ++++++++++++++++++++-
include/uapi/linux/kvm.h | 1 +
5 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 23baf7fce038..d219523bdb70 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -1150,6 +1150,10 @@ The following bits are defined in the flags field:
fields contain a valid state. This bit will be set whenever
KVM_CAP_EXCEPTION_PAYLOAD is enabled.
+- KVM_VCPUEVENT_VALID_TRIPLE_FAULT may be set to signal that the
+ triple_fault_pending field contains a valid state. This bit will
+ be set whenever KVM_CAP_TRIPLE_FAULT_EVENT is enabled.
+
ARM64:
^^^^^^
@@ -1245,6 +1249,10 @@ can be set in the flags field to signal that the
exception_has_payload, exception_payload, and exception.pending fields
contain a valid state and shall be written into the VCPU.
+If KVM_CAP_TRIPLE_FAULT_EVENT is enabled, KVM_VCPUEVENT_VALID_TRIPLE_FAULT
+can be set in flags field to signal that the triple_fault field contains
+a valid state and shall be written into the VCPU.
+
ARM64:
^^^^^^
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9cdc5bbd721f..5b264a24652d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1174,6 +1174,8 @@ struct kvm_arch {
bool guest_can_read_msr_platform_info;
bool exception_payload_enabled;
+ bool triple_fault_event;
+
bool bus_lock_detection_enabled;
bool enable_pmu;
/*
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 21614807a2cb..24c807c8d5f7 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -325,6 +325,7 @@ struct kvm_reinject_control {
#define KVM_VCPUEVENT_VALID_SHADOW 0x00000004
#define KVM_VCPUEVENT_VALID_SMM 0x00000008
#define KVM_VCPUEVENT_VALID_PAYLOAD 0x00000010
+#define KVM_VCPUEVENT_VALID_TRIPLE_FAULT 0x00000020
/* Interrupt shadow states */
#define KVM_X86_SHADOW_INT_MOV_SS 0x01
@@ -359,7 +360,10 @@ struct kvm_vcpu_events {
__u8 smm_inside_nmi;
__u8 latched_init;
} smi;
- __u8 reserved[27];
+ struct {
+ __u8 pending;
+ } triple_fault;
+ __u8 reserved[26];
__u8 exception_has_payload;
__u64 exception_payload;
};
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 04812eaaf61b..e27ccfc88d15 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4293,6 +4293,7 @@ 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_TRIPLE_FAULT_EVENT:
case KVM_CAP_SET_GUEST_DEBUG:
case KVM_CAP_LAST_CPU:
case KVM_CAP_X86_USER_SPACE_MSR:
@@ -4939,6 +4940,10 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
| KVM_VCPUEVENT_VALID_SMM);
if (vcpu->kvm->arch.exception_payload_enabled)
events->flags |= KVM_VCPUEVENT_VALID_PAYLOAD;
+ if (vcpu->kvm->arch.triple_fault_event) {
+ events->triple_fault.pending = kvm_test_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+ events->flags |= KVM_VCPUEVENT_VALID_TRIPLE_FAULT;
+ }
memset(&events->reserved, 0, sizeof(events->reserved));
}
@@ -4952,7 +4957,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
| KVM_VCPUEVENT_VALID_SIPI_VECTOR
| KVM_VCPUEVENT_VALID_SHADOW
| KVM_VCPUEVENT_VALID_SMM
- | KVM_VCPUEVENT_VALID_PAYLOAD))
+ | KVM_VCPUEVENT_VALID_PAYLOAD
+ | KVM_VCPUEVENT_VALID_TRIPLE_FAULT))
return -EINVAL;
if (events->flags & KVM_VCPUEVENT_VALID_PAYLOAD) {
@@ -5025,6 +5031,15 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
}
}
+ if (events->flags & KVM_VCPUEVENT_VALID_TRIPLE_FAULT) {
+ if (!vcpu->kvm->arch.triple_fault_event)
+ return -EINVAL;
+ if (events->triple_fault.pending)
+ kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+ else
+ kvm_clear_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+ }
+
kvm_make_request(KVM_REQ_EVENT, vcpu);
return 0;
@@ -6026,6 +6041,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
kvm->arch.exception_payload_enabled = cap->args[0];
r = 0;
break;
+ case KVM_CAP_TRIPLE_FAULT_EVENT:
+ kvm->arch.triple_fault_event = cap->args[0];
+ r = 0;
+ break;
case KVM_CAP_X86_USER_SPACE_MSR:
kvm->arch.user_space_msr_mask = cap->args[0];
r = 0;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index e10d131edd80..ec75b56229c7 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1153,6 +1153,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_DISABLE_QUIRKS2 213
#define KVM_CAP_VM_TSC_CONTROL 214
#define KVM_CAP_SYSTEM_EVENT_DATA 215
+#define KVM_CAP_TRIPLE_FAULT_EVENT 216
#ifdef KVM_CAP_IRQ_ROUTING
--
2.17.1
