* [PATCH v3] KVM: VMX: Remove redundant handling of bus lock vmexit
@ 2021-10-15 11:59 Hao Xiang
2021-10-15 14:45 ` Sean Christopherson
2021-10-15 16:09 ` Paolo Bonzini
0 siblings, 2 replies; 3+ messages in thread
From: Hao Xiang @ 2021-10-15 11:59 UTC (permalink / raw)
To: kvm; +Cc: shannon.zhao, pbonzini, seanjc, xiaoyao.li, linux-kernel, Hao Xiang
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. Unconditionally Set
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: Xiaoyao Li <xiaoyao.li@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hao Xiang <hao.xiang@linux.alibaba.com>
---
v1 -> v2: a little modifications of comments
v2 -> v3: addressed the review 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..7fb2a3a 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. Unconditionally set the flag here and leave the handling to
+ * vmx_handle_exit().
+ */
+ 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)
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] KVM: VMX: Remove redundant handling of bus lock vmexit
2021-10-15 11:59 [PATCH v3] KVM: VMX: Remove redundant handling of bus lock vmexit Hao Xiang
@ 2021-10-15 14:45 ` Sean Christopherson
2021-10-15 16:09 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Sean Christopherson @ 2021-10-15 14:45 UTC (permalink / raw)
To: Hao Xiang; +Cc: kvm, shannon.zhao, pbonzini, xiaoyao.li, linux-kernel
On Fri, Oct 15, 2021, 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. Unconditionally Set
> 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: Xiaoyao Li <xiaoyao.li@intel.com>
Code review feedback generally doesn't warrant a Suggested-by. The intent of
Suggested-by is to give credit to the idea/approach of a patch, so unless the
review feedback suggests a completely different, noting the input in the delta
(as you did below) is sufficient. And then that way you don't need to juggle
the Suggested-by vs Co-developed-by for me.
> Co-developed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Hao Xiang <hao.xiang@linux.alibaba.com>
> ---
> v1 -> v2: a little modifications of comments
> v2 -> v3: addressed the review 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..7fb2a3a 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. Unconditionally set the flag here and leave the handling to
> + * vmx_handle_exit().
+1 for "Unconditionally" instead of "Force". Any objection to rewording the
second half slightly?
/*
* Hardware may or may not set the BUS_LOCK_DETECTED flag on BUS_LOCK
* VM-Exits. Unconditionally set the flag here and let vmx_handle_exit()
* handle all flavors of bus-lock exits.
*/
Not a big deal in this case, but in the future please give reviewers a chance to
respond and wait for discussion to settle before sending a new version, e.g. I
would happily have replied to Xiaoyao's suggestion in v2.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] KVM: VMX: Remove redundant handling of bus lock vmexit
2021-10-15 11:59 [PATCH v3] KVM: VMX: Remove redundant handling of bus lock vmexit Hao Xiang
2021-10-15 14:45 ` Sean Christopherson
@ 2021-10-15 16:09 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2021-10-15 16:09 UTC (permalink / raw)
To: Hao Xiang, kvm; +Cc: shannon.zhao, seanjc, xiaoyao.li, linux-kernel
On 15/10/21 13:59, 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. Unconditionally Set
> 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: Xiaoyao Li <xiaoyao.li@intel.com>
> Co-developed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Hao Xiang <hao.xiang@linux.alibaba.com>
> ---
> v1 -> v2: a little modifications of comments
> v2 -> v3: addressed the review 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..7fb2a3a 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. Unconditionally set the flag here and leave the handling to
> + * vmx_handle_exit().
> + */
> + 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)
>
Queued, with extra *-by tags removed. Thanks,
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-10-15 16:10 UTC | newest]
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2021-10-15 11:59 [PATCH v3] KVM: VMX: Remove redundant handling of bus lock vmexit Hao Xiang
2021-10-15 14:45 ` Sean Christopherson
2021-10-15 16:09 ` Paolo Bonzini
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