linux-kernel - Re: [PATCH 0/2] KVM: x86: Propagate AMD-specific IBRS bits to guests

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Message-ID: <20230306215450.GFZAZhKnr6zMCeeDNd@fat_crate.local>
Date:   Mon, 6 Mar 2023 22:54:50 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Takahiro Itazuri <itazur@...zon.com>,
        dave.hansen@...ux.intel.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
        x86@...nel.org, zulinx86@...il.com
Subject: Re: [PATCH 0/2] KVM: x86: Propagate AMD-specific IBRS bits to guests

On Mon, Mar 06, 2023 at 10:47:18PM +0100, Paolo Bonzini wrote:
> It's very rare that KVM can provide a CPUID feature if the kernel has
> masked it,

I'm talking about pure hw feature bits which don't need any enablement.
Like AVX512 insns subset support or something else which the hw does
without the need for the kernel.

Those should be KVM-only if baremetal doesn't use them.

-- 
Regards/Gruss,
    Boris.

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