KVM: VMX: Execute WBINVD to keep data consistency with assigned devices

Some guest device driver may leverage the "Non-Snoop" I/O, and explicitly
WBINVD or CLFLUSH to a RAM space. Since migration may occur before WBINVD or
CLFLUSH, we need to maintain data consistency either by:
1: flushing cache (wbinvd) when the guest is scheduled out if there is no
wbinvd exit, or
2: execute wbinvd on all dirty physical CPUs when guest wbinvd exits.

Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 587b99d37d44..56c9b6bd7655 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3424,6 +3424,11 @@ static bool svm_rdtscp_supported(void)
         return false;
 }
 
+static bool svm_has_wbinvd_exit(void)
+{
+        return true;
+}
+
 static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
@@ -3508,6 +3513,8 @@ static struct kvm_x86_ops svm_x86_ops = {
         .rdtscp_supported = svm_rdtscp_supported,
 
         .set_supported_cpuid = svm_set_supported_cpuid,
+
+        .has_wbinvd_exit = svm_has_wbinvd_exit,
 };
 
 static int __init svm_init(void)