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>

2 files changed, 6 insertions, 4 deletions

diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index f46b79f6c16c..fb6117063ea3 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -257,6 +257,11 @@ struct kvm_reinject_control {
 /* When set in flags, include corresponding fields on KVM_SET_VCPU_EVENTS */
 #define KVM_VCPUEVENT_VALID_NMI_PENDING 0x00000001
 #define KVM_VCPUEVENT_VALID_SIPI_VECTOR 0x00000002
+#define KVM_VCPUEVENT_VALID_SHADOW      0x00000004
+
+/* Interrupt shadow states */
+#define KVM_X86_SHADOW_INT_MOV_SS       0x01
+#define KVM_X86_SHADOW_INT_STI          0x02
 
 /* for KVM_GET/SET_VCPU_EVENTS */
 struct kvm_vcpu_events {
@@ -271,7 +276,7 @@ struct kvm_vcpu_events {
                 __u8 injected;
                 __u8 nr;
                 __u8 soft;
-                __u8 pad;
+                __u8 shadow;
         } interrupt;
         struct {
                 __u8 injected;
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 7a6f54fa13ba..2666d7ac3229 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -153,9 +153,6 @@ struct decode_cache {
         struct fetch_cache fetch;
 };
 
-#define X86_SHADOW_INT_MOV_SS  1
-#define X86_SHADOW_INT_STI     2
-
 struct x86_emulate_ctxt {
         /* Register state before/after emulation. */
         struct kvm_vcpu *vcpu;