Messages in this thread | | | Date | Fri, 15 Oct 2021 14:46:11 +0800 | Subject | Re: [PATCH v2] KVM: VMX: Remove redundant handling of bus lock vmexit | From | Xiaoyao Li <> |
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On 10/15/2021 11:57 AM, Hao Xiang wrote: > Hardware may or may not set exit_reason.bus_lock_detected on BUS_LOCK > VM-Exits. Dealing with KVM_RUN_X86_BUS_LOCK in handle_bus_lock_vmexit > could be redundant when exit_reason.basic is EXIT_REASON_BUS_LOCK. > > We can remove redundant handling of bus lock vmexit. Force Setting > exit_reason.bus_lock_detected in handle_bus_lock_vmexit(), and deal with > KVM_RUN_X86_BUS_LOCK only in vmx_handle_exit(). > > Suggested-by: Sean Christopherson <seanjc@google.com> > Signed-off-by: Hao Xiang <hao.xiang@linux.alibaba.com> > --- > v1 -> v2: a little modifications of comments > > arch/x86/kvm/vmx/vmx.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 116b089..22be02e 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -5562,9 +5562,13 @@ static int handle_encls(struct kvm_vcpu *vcpu) > > static int handle_bus_lock_vmexit(struct kvm_vcpu *vcpu) > { > - vcpu->run->exit_reason = KVM_EXIT_X86_BUS_LOCK; > - vcpu->run->flags |= KVM_RUN_X86_BUS_LOCK; > - return 0; > + /* > + * Hardware may or may not set the BUS_LOCK_DETECTED flag on BUS_LOCK > + * VM-Exits, force setting the flag
> so that the logic in vmx_handle_exit() > + * doesn't have to handle the flag and the basic exit reason.
The code itself looks good.
But the comment is partly incorrect. Now we rely only on the bus_lock_detected flag so vmx_handle_exit() must check the flag.
> + */ > + to_vmx(vcpu)->exit_reason.bus_lock_detected = true; > + return 1; > } > > /* > @@ -6051,9 +6055,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) > int ret = __vmx_handle_exit(vcpu, exit_fastpath); > > /* > - * Even when current exit reason is handled by KVM internally, we > - * still need to exit to user space when bus lock detected to inform > - * that there is a bus lock in guest. > + * Exit to user space when bus lock detected to inform that there is > + * a bus lock in guest. > */ > if (to_vmx(vcpu)->exit_reason.bus_lock_detected) { > if (ret > 0) >
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