i386: kvm: extend kvm_{get, put}_vcpu_events to support pending triple fault

For the direct triple faults, i.e. hardware detected and KVM morphed
to VM-Exit, KVM will never lose them. But for triple faults sythesized
by KVM, e.g. the RSM path, if KVM exits to userspace before the request
is serviced, userspace could migrate the VM and lose the triple fault.

A new flag KVM_VCPUEVENT_VALID_TRIPLE_FAULT is defined to signal that
the event.triple_fault_pending field contains a valid state if the
KVM_CAP_X86_TRIPLE_FAULT_EVENT capability is enabled.

Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Message-Id: <20220929072014.20705-2-chenyi.qiang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index ad623d91e4879ebbe0ad03f9510284de53bbd9f9..06884177fad7a19863f71b45de0a928da8509dcf 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6017,6 +6017,7 @@ static void x86_cpu_reset(DeviceState *dev)
     env->exception_has_payload = false;
     env->exception_payload = 0;
     env->nmi_injected = false;
+    env->triple_fault_pending = false;
 #if !defined(CONFIG_USER_ONLY)
     /* We hard-wire the BSP to the first CPU. */
     apic_designate_bsp(cpu->apic_state, s->cpu_index == 0);

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 82004b65b944132781821248914fc34448fc78de..d4124973cec31637f32ea69269e8e0f4eac505e4 100644 (file)
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1739,6 +1739,7 @@ typedef struct CPUArchState {
     uint8_t has_error_code;
     uint8_t exception_has_payload;
     uint64_t exception_payload;
+    uint8_t triple_fault_pending;
     uint32_t ins_len;
     uint32_t sipi_vector;
     bool tsc_valid;

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index f2a96492ce422195d65b797faddd5661e4d46aa7..3ebe8b7f1f7ea224b0723b144f2a31b880d5f825 100644 (file)
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -132,6 +132,7 @@ static int has_xcrs;
 static int has_pit_state2;
 static int has_sregs2;
 static int has_exception_payload;
+static int has_triple_fault_event;
 
 static bool has_msr_mcg_ext_ctl;
 
@@ -2479,6 +2480,16 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
         }
     }
 
+    has_triple_fault_event = kvm_check_extension(s, KVM_CAP_X86_TRIPLE_FAULT_EVENT);
+    if (has_triple_fault_event) {
+        ret = kvm_vm_enable_cap(s, KVM_CAP_X86_TRIPLE_FAULT_EVENT, 0, true);
+        if (ret < 0) {
+            error_report("kvm: Failed to enable triple fault event cap: %s",
+                         strerror(-ret));
+            return ret;
+        }
+    }
+
     ret = kvm_get_supported_msrs(s);
     if (ret < 0) {
         return ret;
@@ -4295,6 +4306,11 @@ static int kvm_put_vcpu_events(X86CPU *cpu, int level)
         }
     }
 
+    if (has_triple_fault_event) {
+        events.flags |= KVM_VCPUEVENT_VALID_TRIPLE_FAULT;
+        events.triple_fault.pending = env->triple_fault_pending;
+    }
+
     return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_VCPU_EVENTS, &events);
 }
 
@@ -4364,6 +4380,10 @@ static int kvm_get_vcpu_events(X86CPU *cpu)
         }
     }
 
+    if (events.flags & KVM_VCPUEVENT_VALID_TRIPLE_FAULT) {
+        env->triple_fault_pending = events.triple_fault.pending;
+    }
+
     env->sipi_vector = events.sipi_vector;
 
     return 0;

diff --git a/target/i386/machine.c b/target/i386/machine.c
index cecd476e98f1ecc9fca1bfcf71e698bf9ac79260..310b1252350876c55b8a40c1d45b2eb309cc3bc8 100644 (file)
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1562,6 +1562,25 @@ static const VMStateDescription vmstate_arch_lbr = {
     }
 };
 
+static bool triple_fault_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->triple_fault_pending;
+}
+
+static const VMStateDescription vmstate_triple_fault = {
+    .name = "cpu/triple_fault",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = triple_fault_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(env.triple_fault_pending, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -1706,6 +1725,7 @@ const VMStateDescription vmstate_x86_cpu = {
         &vmstate_amx_xtile,
 #endif
         &vmstate_arch_lbr,
+        &vmstate_triple_fault,
         NULL
     }
 };