I found PML was broken since below commit:
commit feda805fe7c4ed9cf78158e73b1218752e3b4314
Author: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
Date: Wed Sep 9 14:05:55 2015 +0800
KVM: VMX: unify SECONDARY_VM_EXEC_CONTROL update
Unify the update in vmx_cpuid_update()
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
[Rewrite to use vmcs_set_secondary_exec_control. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
The reason is PML after above commit vmx_cpuid_update calls
vmx_secondary_exec_control, in which PML is disabled unconditionally, as PML is
enabled in creating vcpu. Therefore if vcpu_cpuid_update is called after vcpu is
created, PML will be disabled unexpectedly while log-dirty code still think PML
is used. Actually looks calling vmx_secondary_exec_control in vmx_cpuid_update
is likely to break any VMX features that is enabled/disabled on demand by
updating SECONDARY_VM_EXEC_CONTROL, if vmx_cpuid_update is called between the
feature is enabled and disabled.
Fix this by calling vmcs_read32 to read out SECONDARY_VM_EXEC_CONTROL directly.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4d0aa31..4525c0a7 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8902,7 +8902,7 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u32 secondary_exec_ctl = vmx_secondary_exec_control(vmx);
+ u32 secondary_exec_ctl = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
if (vmx_rdtscp_supported()) {
bool rdtscp_enabled = guest_cpuid_has_rdtscp(vcpu);
--
2.5.0
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