linux-kernel - Re: [PATCH RFC] kvm: x86: Expose AVX512

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Message-ID: <fd861e94-3ea5-3976-9855-05375f869f00@redhat.com>
Date:   Thu, 20 Jun 2019 14:16:22 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Jing Liu <jing2.liu@...ux.intel.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jing2.liu@...el.com
Subject: Re: [PATCH RFC] kvm: x86: Expose AVX512_BF16 feature to guest

On 20/06/19 13:21, Jing Liu wrote:
> +		for (i = 1; i <= times; i++) {
> +			if (*nent >= maxnent)
> +				goto out;
> +			do_cpuid_1_ent(&entry[i], function, i);
> +			entry[i].eax &= F(AVX512_BF16);
> +			entry[i].ebx = 0;
> +			entry[i].ecx = 0;
> +			entry[i].edx = 0;
> +			entry[i].flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
> +			++*nent;

This woud be wrong for i > 1, so instead make this

	if (entry->eax >= 1)

and define F(AVX512_BF16) as a new constant kvm_cpuid_7_1_eax_features.

Paolo