linux-kernel - Re: [PATCH v3 2/3] KVM: SEV-ES: Disallow SEV-ES guests when X86_FEATURE

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Date: Wed, 29 May 2024 16:13:28 +0530
From: Ravi Bangoria <ravi.bangoria@....com>
To: Paolo Bonzini <pbonzini@...hat.com>, seanjc@...gle.com,
 nikunj.dadhania@....com
Cc: thomas.lendacky@....com, tglx@...utronix.de, mingo@...hat.com,
 bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 michael.roth@....com, pankaj.gupta@....com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, santosh.shukla@....com, ravi.bangoria@....com
Subject: Re: [PATCH v3 2/3] KVM: SEV-ES: Disallow SEV-ES guests when
 X86_FEATURE_LBRV is absent

On 5/28/2024 10:03 PM, Paolo Bonzini wrote:
> On 5/23/24 14:18, Ravi Bangoria wrote:
>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>> index 489b0183f37d..dcb5eb00a4f5 100644
>> --- a/arch/x86/kvm/svm/svm.c
>> +++ b/arch/x86/kvm/svm/svm.c
>> @@ -5308,11 +5308,17 @@ static __init int svm_hardware_setup(void)
>>         nrips = nrips && boot_cpu_has(X86_FEATURE_NRIPS);
>>   +    if (lbrv) {
>> +        if (!boot_cpu_has(X86_FEATURE_LBRV))
>> +            lbrv = false;
>> +        else
>> +            pr_info("LBR virtualization supported\n");
>> +    }
>>       /*
>>        * Note, SEV setup consumes npt_enabled and enable_mmio_caching (which
>>        * may be modified by svm_adjust_mmio_mask()), as well as nrips.
>>        */
> 
> Since it consumes nrips, just make lbrv non-static:

Sure.

Thanks,
Ravi