[PATCH 6/7] KVM: svm: set/clear all DR intercepts in one swoop

[Paolo Bonzini]

Unlike other intercepts, debug register intercepts will be modified
in hot paths if the guest OS is bad or otherwise gets tricked into
doing so.

Avoid calling recalc_intercepts 16 times for debug registers.

Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
 arch/x86/kvm/svm.c | 41 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 64d9bb9590e3..5ed67e9739f6 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -303,20 +303,35 @@ static inline bool is_cr_intercept(struct vcpu_svm *svm, 
int bit)
        return vmcb->control.intercept_cr & (1U << bit);
 }
 
-static inline void set_dr_intercept(struct vcpu_svm *svm, int bit)
+static inline void set_dr_intercepts(struct vcpu_svm *svm)
 {
        struct vmcb *vmcb = get_host_vmcb(svm);
 
-       vmcb->control.intercept_dr |= (1U << bit);
+       vmcb->control.intercept_dr = (1 << INTERCEPT_DR0_READ)
+               | (1 << INTERCEPT_DR1_READ)
+               | (1 << INTERCEPT_DR2_READ)
+               | (1 << INTERCEPT_DR3_READ)
+               | (1 << INTERCEPT_DR4_READ)
+               | (1 << INTERCEPT_DR5_READ)
+               | (1 << INTERCEPT_DR6_READ)
+               | (1 << INTERCEPT_DR7_READ)
+               | (1 << INTERCEPT_DR0_WRITE)
+               | (1 << INTERCEPT_DR1_WRITE)
+               | (1 << INTERCEPT_DR2_WRITE)
+               | (1 << INTERCEPT_DR3_WRITE)
+               | (1 << INTERCEPT_DR4_WRITE)
+               | (1 << INTERCEPT_DR5_WRITE)
+               | (1 << INTERCEPT_DR6_WRITE)
+               | (1 << INTERCEPT_DR7_WRITE);
 
        recalc_intercepts(svm);
 }
 
-static inline void clr_dr_intercept(struct vcpu_svm *svm, int bit)
+static inline void clr_dr_intercepts(struct vcpu_svm *svm)
 {
        struct vmcb *vmcb = get_host_vmcb(svm);
 
-       vmcb->control.intercept_dr &= ~(1U << bit);
+       vmcb->control.intercept_dr = 0;
 
        recalc_intercepts(svm);
 }
@@ -1080,23 +1095,7 @@ static void init_vmcb(struct vcpu_svm *svm)
        set_cr_intercept(svm, INTERCEPT_CR4_WRITE);
        set_cr_intercept(svm, INTERCEPT_CR8_WRITE);
 
-       set_dr_intercept(svm, INTERCEPT_DR0_READ);
-       set_dr_intercept(svm, INTERCEPT_DR1_READ);
-       set_dr_intercept(svm, INTERCEPT_DR2_READ);
-       set_dr_intercept(svm, INTERCEPT_DR3_READ);
-       set_dr_intercept(svm, INTERCEPT_DR4_READ);
-       set_dr_intercept(svm, INTERCEPT_DR5_READ);
-       set_dr_intercept(svm, INTERCEPT_DR6_READ);
-       set_dr_intercept(svm, INTERCEPT_DR7_READ);
-
-       set_dr_intercept(svm, INTERCEPT_DR0_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR1_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR2_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR3_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR4_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR5_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR6_WRITE);
-       set_dr_intercept(svm, INTERCEPT_DR7_WRITE);
+       set_dr_intercepts(svm);
 
        set_exception_intercept(svm, PF_VECTOR);
        set_exception_intercept(svm, UD_VECTOR);
-- 
1.8.3.1


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