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@xxxxxxxxxx>
Signed-off-by: Hao Xiang <hao.xiang@xxxxxxxxxxxxxxxxx>
---
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)
