From e42c68281b444f9a20d72a062f8c6fd0d31e4de8 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <kernellwpQ@gmail.com>
Date: Sat, 12 Sep 2020 02:16:39 -0400
Subject: [PATCH] KVM: SVM: avoid emulation with stale next_rip
svm->next_rip is reset in svm_vcpu_run() only after calling
svm_exit_handlers_fastpath(), which will cause SVM's
skip_emulated_instruction() to write a stale RIP.
We can move svm_exit_handlers_fastpath towards the end of
svm_vcpu_run(). To align VMX with SVM, keep svm_complete_interrupts()
close as well.
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Paul K. <kronenpj@kronenpj.dyndns.org>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
[Also move vmcb_mark_all_clean before any possible write to the VMCB.
- Paolo]
---
arch/x86/kvm/svm/svm.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 03dd7bac803488..8ba4a32843fa3c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2938,8 +2938,6 @@ static int handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
if (npt_enabled)
vcpu->arch.cr3 = svm->vmcb->save.cr3;
- svm_complete_interrupts(svm);
-
if (is_guest_mode(vcpu)) {
int vmexit;
@@ -3504,7 +3502,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
stgi();
/* Any pending NMI will happen here */
- exit_fastpath = svm_exit_handlers_fastpath(vcpu);
if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
kvm_after_interrupt(&svm->vcpu);
@@ -3518,6 +3515,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
}
svm->vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
+ vmcb_mark_all_clean(svm->vmcb);
/* if exit due to PF check for async PF */
if (svm->vmcb->control.exit_code == SVM_EXIT_EXCP_BASE + PF_VECTOR)
@@ -3537,7 +3535,8 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
SVM_EXIT_EXCP_BASE + MC_VECTOR))
svm_handle_mce(svm);
- vmcb_mark_all_clean(svm->vmcb);
+ svm_complete_interrupts(svm);
+ exit_fastpath = svm_exit_handlers_fastpath(vcpu);
return exit_fastpath;
}
--
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