Messages in this thread Patch in this message | | | Date | Fri, 15 Oct 2021 15:28:13 +0800 | Subject | Re: [PATCH v2] KVM: VMX: Remove redundant handling of bus lock vmexit | From | Hao Xiang <> |
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On 2021/10/15 14:46, Xiaoyao Li wrote: > 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. >Thank you for you advice. Is the following comment ok? /* * Hardware may or may not set the BUS_LOCK_DETECTED flag on BUS_LOCK * VM-Exits. Forcely set the flag here, then check the flag in * vmx_handle_exit() and handle the bus lock vmexit if the flag is * set. */
>> + */ >> + 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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