KVM: x86: Save&restore interrupt shadow mask

The interrupt shadow created by STI or MOV-SS-like operations is part of
the VCPU state and must be preserved across migration. Transfer it in
the spare padding field of kvm_vcpu_events.interrupt.

As a side effect we now have to make vmx_set_interrupt_shadow robust
against both shadow types being set. Give MOV SS a higher priority and
skip STI in that case to avoid that VMX throws a fault on next entry.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2b1c9f2fb8dd..84ffd95ee198 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2111,6 +2111,9 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
                 vcpu->arch.interrupt.pending && !vcpu->arch.interrupt.soft;
         events->interrupt.nr = vcpu->arch.interrupt.nr;
         events->interrupt.soft = 0;
+        events->interrupt.shadow =
+                kvm_x86_ops->get_interrupt_shadow(vcpu,
+                        KVM_X86_SHADOW_INT_MOV_SS | KVM_X86_SHADOW_INT_STI);
 
         events->nmi.injected = vcpu->arch.nmi_injected;
         events->nmi.pending = vcpu->arch.nmi_pending;
@@ -2119,7 +2122,8 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
         events->sipi_vector = vcpu->arch.sipi_vector;
 
         events->flags = (KVM_VCPUEVENT_VALID_NMI_PENDING
-                         | KVM_VCPUEVENT_VALID_SIPI_VECTOR);
+                         | KVM_VCPUEVENT_VALID_SIPI_VECTOR
+                         | KVM_VCPUEVENT_VALID_SHADOW);
 
         vcpu_put(vcpu);
 }
@@ -2128,7 +2132,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
                                               struct kvm_vcpu_events *events)
 {
         if (events->flags & ~(KVM_VCPUEVENT_VALID_NMI_PENDING
-                              | KVM_VCPUEVENT_VALID_SIPI_VECTOR))
+                              | KVM_VCPUEVENT_VALID_SIPI_VECTOR
+                              | KVM_VCPUEVENT_VALID_SHADOW))
                 return -EINVAL;
 
         vcpu_load(vcpu);
@@ -2143,6 +2148,9 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
         vcpu->arch.interrupt.soft = events->interrupt.soft;
         if (vcpu->arch.interrupt.pending && irqchip_in_kernel(vcpu->kvm))
                 kvm_pic_clear_isr_ack(vcpu->kvm);
+        if (events->flags & KVM_VCPUEVENT_VALID_SHADOW)
+                kvm_x86_ops->set_interrupt_shadow(vcpu,
+                                                  events->interrupt.shadow);
 
         vcpu->arch.nmi_injected = events->nmi.injected;
         if (events->flags & KVM_VCPUEVENT_VALID_NMI_PENDING)