Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v6 8/8] kvm: vmx: virtualize split lock detection | Date | Thu, 26 Mar 2020 12:10:18 +0100 |
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Xiaoyao Li <xiaoyao.li@intel.com> writes: > On 3/25/2020 8:40 AM, Thomas Gleixner wrote: >> Xiaoyao Li <xiaoyao.li@intel.com> 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
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