linux-kernel - Re: [PATCH v1 2/6] KVM: x86: Virtualize CR4.LASS

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Date:   Wed, 28 Jun 2023 16:19:11 +0800
From:   Zeng Guang <guang.zeng@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        H Peter Anvin <hpa@...or.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/6] KVM: x86: Virtualize CR4.LASS


On 6/28/2023 1:43 AM, Sean Christopherson wrote:
> On Thu, Jun 01, 2023, Zeng Guang wrote:
>> Virtualize CR4.LASS[bit 27] under KVM control instead of being guest-owned
>> as CR4.LASS generally set once for each vCPU at boot time and won't be
>> toggled at runtime. Besides, only if VM has LASS capability enumerated with
>> CPUID.(EAX=07H.ECX=1):EAX.LASS[bit 6], KVM allows guest software to be able
>> to set CR4.LASS.
>>
>> Updating cr4_fixed1 to set CR4.LASS bit in the emulated IA32_VMX_CR4_FIXED1
>> MSR for guests and allow guests to enable LASS in nested VMX operaion as well.
> s/operaion/operation.
Will fix in next version. Thanks.