[PATCH MANUALSEL 5.14 3/5] KVM: VMX: Remove redundant handling of bus lock vmexit

Sasha Levin
2021-10-25T20:38:41Z

From: Hao Xiang <hao.xiang@linux.alibaba.com>

[ Upstream commit d61863c66f9b443192997613cd6aeca3f65cc313 ]

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().

Signed-off-by: Hao Xiang <hao.xiang@linux.alibaba.com>
Message-Id: <1634299161-30101-1-git-send-email-hao.xiang@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 55de1eb135f9..87150b3c9c5f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5551,9 +5551,13 @@ 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;
}

/*
@@ -6039,9 +6043,8 @@ 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)
--
2.33.0