Add a helper to detect writes to the Xen hypercall page MSR, and provide a
stub for CONFIG_KVM_XEN=n to optimize out the check for kernels built
without Xen support.
Reviewed-by: Paul Durrant <paul@xxxxxxx>
Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 2 +-
arch/x86/kvm/xen.h | 10 ++++++++++
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 462a5cd6ac4a..12c60adb7349 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3738,7 +3738,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
* page setup; it could incur locking paths which are not expected
* if userspace sets the MSR in an unusual location.
*/
- if (msr && msr == vcpu->kvm->arch.xen_hvm_config.msr &&
+ if (kvm_xen_is_hypercall_page_msr(vcpu->kvm, msr) &&
!msr_info->host_initiated)
return kvm_xen_write_hypercall_page(vcpu, data);
diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index f5841d9000ae..e92e06926f76 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -56,6 +56,11 @@ static inline bool kvm_xen_msr_enabled(struct kvm *kvm)
kvm->arch.xen_hvm_config.msr;
}
+static inline bool kvm_xen_is_hypercall_page_msr(struct kvm *kvm, u32 msr)
+{
+ return msr && msr == kvm->arch.xen_hvm_config.msr;
+}
+
static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
{
return static_branch_unlikely(&kvm_xen_enabled.key) &&
@@ -124,6 +129,11 @@ static inline bool kvm_xen_msr_enabled(struct kvm *kvm)
return false;
}
+static inline bool kvm_xen_is_hypercall_page_msr(struct kvm *kvm, u32 msr)
+{
+ return false;
+}
+
static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
{
return false;
--
2.48.1.601.g30ceb7b040-goog
