linux-kernel - Re: [PATCH v8 23/40] KVM: x86: move lookup of indexed CPUID leafs to helper

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Date:   Thu, 6 Jan 2022 12:46:37 -0600
From:   Venu Busireddy <venu.busireddy@...cle.com>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v8 23/40] KVM: x86: move lookup of indexed CPUID leafs to
 helper

On 2021-12-10 09:43:15 -0600, Brijesh Singh wrote:
> From: Michael Roth <michael.roth@....com>
> 
> Determining which CPUID leafs have significant ECX/index values is
> also needed by guest kernel code when doing SEV-SNP-validated CPUID
> lookups. Move this to common code to keep future updates in sync.
> 
> Signed-off-by: Michael Roth <michael.roth@....com>
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>

Reviewed-by: Venu Busireddy <venu.busireddy@...cle.com>

> ---
>  arch/x86/include/asm/cpuid.h | 26 ++++++++++++++++++++++++++
>  arch/x86/kvm/cpuid.c         | 17 ++---------------
>  2 files changed, 28 insertions(+), 15 deletions(-)
>  create mode 100644 arch/x86/include/asm/cpuid.h
> 
> diff --git a/arch/x86/include/asm/cpuid.h b/arch/x86/include/asm/cpuid.h
> new file mode 100644
> index 000000000000..61426eb1f665
> --- /dev/null
> +++ b/arch/x86/include/asm/cpuid.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_X86_CPUID_H
> +#define _ASM_X86_CPUID_H
> +
> +static __always_inline bool cpuid_function_is_indexed(u32 function)
> +{
> +	switch (function) {
> +	case 4:
> +	case 7:
> +	case 0xb:
> +	case 0xd:
> +	case 0xf:
> +	case 0x10:
> +	case 0x12:
> +	case 0x14:
> +	case 0x17:
> +	case 0x18:
> +	case 0x1f:
> +	case 0x8000001d:
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +#endif /* _ASM_X86_CPUID_H */
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 07e9215e911d..6b99e8e87480 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -19,6 +19,7 @@
>  #include <asm/user.h>
>  #include <asm/fpu/xstate.h>
>  #include <asm/sgx.h>
> +#include <asm/cpuid.h>
>  #include "cpuid.h"
>  #include "lapic.h"
>  #include "mmu.h"
> @@ -626,22 +627,8 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
>  	cpuid_count(entry->function, entry->index,
>  		    &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);
>  
> -	switch (function) {
> -	case 4:
> -	case 7:
> -	case 0xb:
> -	case 0xd:
> -	case 0xf:
> -	case 0x10:
> -	case 0x12:
> -	case 0x14:
> -	case 0x17:
> -	case 0x18:
> -	case 0x1f:
> -	case 0x8000001d:
> +	if (cpuid_function_is_indexed(function))
>  		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
> -		break;
> -	}
>  
>  	return entry;
>  }
> -- 
> 2.25.1
>