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KVM: SVM: avoid emulation with stale next_rip

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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]
This commit is contained in:
Wanpeng Li 2020-09-12 02:16:39 -04:00 committed by Paolo Bonzini
parent d831de1772
commit e42c68281b
1 changed files with 3 additions and 4 deletions
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7
arch/x86/kvm/svm/svm.c
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@ -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;
}