Re: [PATCH v1 3/6] KVM: VMX: Add new ops in kvm_x86_ops for LASS violation check

From: Zeng Guang <guang.zeng@intel.com>
To: "Gao, Chao" <chao.gao@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, "Christopherson,,
	Sean" <seanjc@google.com>, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	H Peter Anvin <hpa@zytor.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 3/6] KVM: VMX: Add new ops in kvm_x86_ops for LASS violation check
Date: Tue, 6 Jun 2023 14:22:51 +0800	[thread overview]
Message-ID: <c4166c88-1f99-37bd-bf7a-ac95ba6e82e7@intel.com> (raw)
In-Reply-To: <ZH1a2ep4o2xiI5wO@chao-email>


On 6/5/2023 11:47 AM, Gao, Chao wrote:
> On Thu, Jun 01, 2023 at 10:23:06PM +0800, Zeng Guang wrote:
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 92d8e65fe88c..98666d1e7727 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1731,6 +1731,8 @@ struct kvm_x86_ops {
>> 	 * Returns vCPU specific APICv inhibit reasons
>> 	 */
>> 	unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu);
>> +
>> +	bool (*check_lass)(struct kvm_vcpu *vcpu, u64 access, u64 la, u32 flags);
> It is better to declare the @la as gva_t since the address is a virtual address.
>
> Both @access and @flags provide additional informaiton about a memory access. I
> think we can drop one of them e.g. adding a new bit X86EMUL_F_IMPLICIT_ACCESS.
>
> Or maybe in the first place, we can just extend PFERR_? for SKIP_LASS/LAM
> behavior instead of adding another set of flags (X86EMUL_F_?). The benefit of
> adding new flags is they won't collide with future hardware extensions. I am not
> sure.
Make sense. Prefer to adding a new bit of X86EMUL flags.
PFERR_ is used for page fault case and actually not proper to be taken for
LASS/LAM usage.