Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes:
> On 3/25/2020 8:40 AM, Thomas Gleixner wrote:
>> Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes:
>>> static int handle_exception_nmi(struct kvm_vcpu *vcpu)
>>> {
>>> struct vcpu_vmx *vmx = to_vmx(vcpu);
>>> @@ -4725,12 +4746,13 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
>>> case AC_VECTOR:
>>> /*
>>> * Reflect #AC to the guest if it's expecting the #AC, i.e. has
>>> - * legacy alignment check enabled. Pre-check host split lock
>>> - * support to avoid the VMREADs needed to check legacy #AC,
>>> - * i.e. reflect the #AC if the only possible source is legacy
>>> - * alignment checks.
>>> + * legacy alignment check enabled or split lock detect enabled.
>>> + * Pre-check host split lock support to avoid further check of
>>> + * guest, i.e. reflect the #AC if host doesn't enable split lock
>>> + * detection.
>>> */
>>> if (!split_lock_detect_on() ||
>>> + guest_cpu_split_lock_detect_on(vmx) ||
>>> guest_cpu_alignment_check_enabled(vcpu)) {
>>
>> If the host has split lock detection disabled then how is the guest
>> supposed to have it enabled in the first place?
>>
> It is ||
Again. If the host has it disabled, then the feature flag is OFF. So
how is the hypervisor exposing it in the first place?
Thanks,
tglx
