linux-kernel - Re: [PATCH] KVM: x86/cpuid: Expose the true number of available ASIDs

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Message-ID: <3d2ad944-9e0c-dea7-f0e4-4e55072ccf99@redhat.com>
Date:   Thu, 15 Jul 2021 13:19:16 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Like Xu <like.xu.linux@...il.com>, Joerg Roedel <joro@...tes.org>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] KVM: x86/cpuid: Expose the true number of available ASIDs

On 15/07/21 12:45, Like Xu wrote:
> The original fixed number "8" was first introduced 11 years ago. Time has
> passed and now let KVM report the true number of address space identifiers
> (ASIDs) that are supported by the processor returned in Fn8000_000A_EBX.
> 
> It helps user-space to make better decisions about guest values.
>
> -		entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper
> -				   ASID emulation to nested SVM */

Why, since we don't have ASID emulation yet anyway?

Paolo