From: Mihai Dontu <mdontu@xxxxxxxxxxxxxxx>
Inform the guest introspection tool that an MSR is going to be changed.
The kvmi_msr_event() function will check a bitmap of MSR-s of interest
(configured via a KVMI_EVENT_CONTROL(KVMI_MSR_CONTROL) request) and, if
the new value differs from the previous one, it will generate a
notification. The introspection tool can respond by allowing the guest
to continue with normal execution or by discarding the change.
This is meant to prevent malicious changes to MSR-s such as
MSR_IA32_SYSENTER_EIP.
Signed-off-by: Mihai Dontu <mdontu@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 248fb7e99423..b7d2a9901665 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1090,6 +1090,23 @@ EXPORT_SYMBOL_GPL(kvm_enable_efer_bits);
*/
int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
{
+ if (!msr->host_initiated) {
+ struct msr_data __msr;
+
+ memset(&__msr, 0, sizeof(__msr));
+ __msr.host_initiated = true;
+ __msr.index = msr->index;
+
+ if (!kvm_get_msr(vcpu, &__msr)) {
+ u64 data = msr->data;
+
+ if (kvmi_msr_event(vcpu, msr->index, __msr.data, &data))
+ msr->data = data;
+ else
+ return 0;
+ }
+ }
+
switch (msr->index) {
case MSR_FS_BASE:
case MSR_GS_BASE:
--
2.12.2
