From: David Kaplan <david.kaplan@xxxxxxx>
Reduce the number of exits by avoiding exiting when the guest writes TS or MP
bits of CR0. INTERCEPT_CR0_WRITE intercepts all writes to CR0 including TS and
MP bits. It intercepts these even if INTERCEPT_SELECTIVE_CR0 is set. What we
should be doing is setting INTERCEPT_SELECTIVE_CR0 and not setting
INTERCEPT_CR0_WRITE.
Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
[added remove of clr_cr_intercept in init_vmcb, fixed check in handle_exit,
added emulation on interception back in, forward ported, tested]
Signed-off-by: Joel Schopp <joel.schopp@xxxxxxx>
---
arch/x86/kvm/svm.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d319e0c..55822e5 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1093,7 +1093,6 @@ static void init_vmcb(struct vcpu_svm *svm)
set_cr_intercept(svm, INTERCEPT_CR0_READ);
set_cr_intercept(svm, INTERCEPT_CR3_READ);
set_cr_intercept(svm, INTERCEPT_CR4_READ);
- set_cr_intercept(svm, INTERCEPT_CR0_WRITE);
set_cr_intercept(svm, INTERCEPT_CR3_WRITE);
set_cr_intercept(svm, INTERCEPT_CR4_WRITE);
set_cr_intercept(svm, INTERCEPT_CR8_WRITE);
@@ -1539,10 +1538,8 @@ static void update_cr0_intercept(struct vcpu_svm *svm)
if (gcr0 == *hcr0 && svm->vcpu.fpu_active) {
clr_cr_intercept(svm, INTERCEPT_CR0_READ);
- clr_cr_intercept(svm, INTERCEPT_CR0_WRITE);
} else {
set_cr_intercept(svm, INTERCEPT_CR0_READ);
- set_cr_intercept(svm, INTERCEPT_CR0_WRITE);
}
}
@@ -2940,7 +2937,11 @@ static int cr_interception(struct vcpu_svm *svm)
return emulate_on_interception(svm);
reg = svm->vmcb->control.exit_info_1 & SVM_EXITINFO_REG_MASK;
- cr = svm->vmcb->control.exit_code - SVM_EXIT_READ_CR0;
+
+ if (svm->vmcb->control.exit_code == SVM_EXIT_CR0_SEL_WRITE)
+ cr = 16;
+ else
+ cr = svm->vmcb->control.exit_code - SVM_EXIT_READ_CR0;
err = 0;
if (cr >= 16) { /* mov to cr */
@@ -3325,7 +3326,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_READ_CR3] = cr_interception,
[SVM_EXIT_READ_CR4] = cr_interception,
[SVM_EXIT_READ_CR8] = cr_interception,
- [SVM_EXIT_CR0_SEL_WRITE] = emulate_on_interception,
+ [SVM_EXIT_CR0_SEL_WRITE] = cr_interception,
[SVM_EXIT_WRITE_CR0] = cr_interception,
[SVM_EXIT_WRITE_CR3] = cr_interception,
[SVM_EXIT_WRITE_CR4] = cr_interception,
@@ -3502,7 +3503,7 @@ static int handle_exit(struct kvm_vcpu *vcpu)
struct kvm_run *kvm_run = vcpu->run;
u32 exit_code = svm->vmcb->control.exit_code;
- if (!is_cr_intercept(svm, INTERCEPT_CR0_WRITE))
+ if (!is_cr_intercept(svm, INTERCEPT_SELECTIVE_CR0))
vcpu->arch.cr0 = svm->vmcb->save.cr0;
if (npt_enabled)
vcpu->arch.cr3 = svm->vmcb->save.cr3;
--
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