From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
So that future optimizations related to shadowed fields don't need to
define their own switch statement.
Add a BUILD_BUG_ON() to ensure at least one of the types (RW vs RO) is
defined when including vmcs_shadow_fields.h (guess who keeps mistyping
SHADOW_FIELD_RO as SHADOW_FIELD_R0).
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 71 ++++++++++++++++++++---------------
arch/x86/kvm/vmx/vmcs_shadow_fields.h | 4 ++
2 files changed, 44 insertions(+), 31 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index fc2b8f4cf45f..a6fe6cfe96f6 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4420,6 +4420,29 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
return nested_vmx_succeed(vcpu);
}
+static bool is_shadow_field_rw(unsigned long field)
+{
+ switch (field) {
+#define SHADOW_FIELD_RW(x, y) case x:
+#include "vmcs_shadow_fields.h"
+ return true;
+ default:
+ break;
+ }
+ return false;
+}
+
+static bool is_shadow_field_ro(unsigned long field)
+{
+ switch (field) {
+#define SHADOW_FIELD_RO(x, y) case x:
+#include "vmcs_shadow_fields.h"
+ return true;
+ default:
+ break;
+ }
+ return false;
+}
static int handle_vmwrite(struct kvm_vcpu *vcpu)
{
@@ -4503,41 +4526,27 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
vmcs12_write_any(vmcs12, field, offset, field_value);
/*
- * Do not track vmcs12 dirty-state if in guest-mode
- * as we actually dirty shadow vmcs12 instead of vmcs12.
+ * Do not track vmcs12 dirty-state if in guest-mode as we actually
+ * dirty shadow vmcs12 instead of vmcs12. Fields that can be updated
+ * by L1 without a vmexit are always updated in the vmcs02, i.e' don't
+ * "dirty" vmcs12, all others go down the prepare_vmcs02() slow path.
*/
- if (!is_guest_mode(vcpu)) {
- switch (field) {
-#define SHADOW_FIELD_RW(x, y) case x:
-#include "vmcs_shadow_fields.h"
- /*
- * The fields that can be updated by L1 without a vmexit are
- * always updated in the vmcs02, the others go down the slow
- * path of prepare_vmcs02.
- */
- break;
-
-#define SHADOW_FIELD_RO(x, y) case x:
-#include "vmcs_shadow_fields.h"
- /*
- * L1 can read these fields without exiting, ensure the
- * shadow VMCS is up-to-date.
- */
- if (enable_shadow_vmcs) {
- preempt_disable();
- vmcs_load(vmx->vmcs01.shadow_vmcs);
+ if (!is_guest_mode(vcpu) && !is_shadow_field_rw(field)) {
+ /*
+ * L1 can read these fields without exiting, ensure the
+ * shadow VMCS is up-to-date.
+ */
+ if (enable_shadow_vmcs && is_shadow_field_ro(field)) {
+ preempt_disable();
+ vmcs_load(vmx->vmcs01.shadow_vmcs);
- __vmcs_writel(field, field_value);
+ __vmcs_writel(field, field_value);
- vmcs_clear(vmx->vmcs01.shadow_vmcs);
- vmcs_load(vmx->loaded_vmcs->vmcs);
- preempt_enable();
- }
- /* fall through */
- default:
- vmx->nested.dirty_vmcs12 = true;
- break;
+ vmcs_clear(vmx->vmcs01.shadow_vmcs);
+ vmcs_load(vmx->loaded_vmcs->vmcs);
+ preempt_enable();
}
+ vmx->nested.dirty_vmcs12 = true;
}
return nested_vmx_succeed(vcpu);
diff --git a/arch/x86/kvm/vmx/vmcs_shadow_fields.h b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
index 2cfa19ca158e..4cea018ba285 100644
--- a/arch/x86/kvm/vmx/vmcs_shadow_fields.h
+++ b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
@@ -1,3 +1,7 @@
+#if !defined(SHADOW_FIELD_RO) && !defined(SHADOW_FIELD_RW)
+BUILD_BUG_ON(1)
+#endif
+
#ifndef SHADOW_FIELD_RO
#define SHADOW_FIELD_RO(x, y)
#endif
--
1.8.3.1
