KVM: SVM: Add function to recalculate intercept masks

This patch adds a function to recalculate the effective
intercepts masks when the vcpu is in guest-mode and either
the host or the guest intercept masks change.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 26 insertions, 17 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2ae94b540358..74f89f0b9e3f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -192,6 +192,26 @@ static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
         return container_of(vcpu, struct vcpu_svm, vcpu);
 }
 
+static void recalc_intercepts(struct vcpu_svm *svm)
+{
+        struct vmcb_control_area *c, *h;
+        struct nested_state *g;
+
+        if (!is_guest_mode(&svm->vcpu))
+                return;
+
+        c = &svm->vmcb->control;
+        h = &svm->nested.hsave->control;
+        g = &svm->nested;
+
+        c->intercept_cr_read = h->intercept_cr_read | g->intercept_cr_read;
+        c->intercept_cr_write = h->intercept_cr_write | g->intercept_cr_write;
+        c->intercept_dr_read = h->intercept_dr_read | g->intercept_dr_read;
+        c->intercept_dr_write = h->intercept_dr_write | g->intercept_dr_write;
+        c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions;
+        c->intercept = h->intercept | g->intercept;
+}
+
 static inline void enable_gif(struct vcpu_svm *svm)
 {
         svm->vcpu.arch.hflags |= HF_GIF_MASK;
@@ -2273,23 +2293,6 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
         /* We don't want to see VMMCALLs from a nested guest */
         svm->vmcb->control.intercept &= ~(1ULL << INTERCEPT_VMMCALL);
 
-        /*
-         * We don't want a nested guest to be more powerful than the guest, so
-         * all intercepts are ORed
-         */
-        svm->vmcb->control.intercept_cr_read |=
-                nested_vmcb->control.intercept_cr_read;
-        svm->vmcb->control.intercept_cr_write |=
-                nested_vmcb->control.intercept_cr_write;
-        svm->vmcb->control.intercept_dr_read |=
-                nested_vmcb->control.intercept_dr_read;
-        svm->vmcb->control.intercept_dr_write |=
-                nested_vmcb->control.intercept_dr_write;
-        svm->vmcb->control.intercept_exceptions |=
-                nested_vmcb->control.intercept_exceptions;
-
-        svm->vmcb->control.intercept |= nested_vmcb->control.intercept;
-
         svm->vmcb->control.lbr_ctl = nested_vmcb->control.lbr_ctl;
         svm->vmcb->control.int_vector = nested_vmcb->control.int_vector;
         svm->vmcb->control.int_state = nested_vmcb->control.int_state;
@@ -2302,6 +2305,12 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
         /* Enter Guest-Mode */
         enter_guest_mode(&svm->vcpu);
 
+        /*
+         * Merge guest and host intercepts - must be called  with vcpu in
+         * guest-mode to take affect here
+         */
+        recalc_intercepts(svm);
+
         svm->nested.vmcb = vmcb_gpa;
 
         enable_gif(svm);