From: Anish Ghulati <aghulati@xxxxxxxxxx>
For all direct access MSRs, disable the MSR interception explicitly.
svm_disable_intercept_for_msr() checks the new MSR filter and ensures that
KVM enables interception if userspace wants to filter the MSR.
This change is similar to the VMX change:
d895f28ed6da ("KVM: VMX: Skip filter updates for MSRs that KVM is already intercepting")
Adopting in SVM to align the implementations.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Co-developed-by: Aaron Lewis <aaronlewis@xxxxxxxxxx>
Signed-off-by: Anish Ghulati <aghulati@xxxxxxxxxx>
---
arch/x86/kvm/svm/svm.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b982729ef7638..37b8683849ed2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1025,17 +1025,21 @@ static void svm_msr_filter_changed(struct kvm_vcpu *vcpu)
u32 i;
/*
- * Set intercept permissions for all direct access MSRs again. They
- * will automatically get filtered through the MSR filter, so we are
- * back in sync after this.
+ * Redo intercept permissions for MSRs that KVM is passing through to
+ * the guest. Disabling interception will check the new MSR filter and
+ * ensure that KVM enables interception if usersepace wants to filter
+ * the MSR. MSRs that KVM is already intercepting don't need to be
+ * refreshed since KVM is going to intercept them regardless of what
+ * userspace wants.
*/
for (i = 0; direct_access_msrs[i].index != MSR_INVALID; i++) {
u32 msr = direct_access_msrs[i].index;
- u32 read = !test_bit(i, svm->shadow_msr_intercept.read);
- u32 write = !test_bit(i, svm->shadow_msr_intercept.write);
- /* FIXME: Align the polarity of the bitmaps and params. */
- set_msr_interception_bitmap(vcpu, svm->msrpm, msr, read, write);
+ if (!test_bit(i, svm->shadow_msr_intercept.read))
+ svm_disable_intercept_for_msr(vcpu, msr, MSR_TYPE_R);
+
+ if (!test_bit(i, svm->shadow_msr_intercept.write))
+ svm_disable_intercept_for_msr(vcpu, msr, MSR_TYPE_W);
}
}
--
2.47.0.338.g60cca15819-goog
