linux-kernel - Re: [PATCH v2] KVM: SEV: Add KVM_SEV_SNP_HV_REPORT

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Message-ID: <7b3c264c-03bb-4dc5-b5c6-24fb0bd179cf@amd.com>
Date: Fri, 5 Dec 2025 08:28:41 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Thomas Courrege <thomas.courrege@...es.tech>, pbonzini@...hat.com,
 seanjc@...gle.com, corbet@....net, ashish.kalra@....com, john.allen@....com,
 herbert@...dor.apana.org.au, nikunj@....com
Cc: x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-crypto@...r.kernel.org
Subject: Re: [PATCH v2] KVM: SEV: Add KVM_SEV_SNP_HV_REPORT_REQ command

On 12/4/25 07:21, Thomas Courrege wrote:
> On 12/2/25 8:29 PM, Tom Lendacky wrote:
> 
>>> +
>>> +e_free_rsp:
>>> +	/* contains sensitive data */
>>> +	memzero_explicit(report_rsp, PAGE_SIZE);
>> Does it? What is sensitive that needs to be cleared?
> 
> Combine with others reports, it could allow to do an inventory of the guests,
> which ones share the same author, measurement, policy...
> It is not needed, but generating a report is not a common operation so
> performance is not an issue here. What do you think is the best to do ?

Can't userspace do that just by generating/requesting reports? If there
are no keys, IVs, secrets, etc. in the memory, I don't see what the
memzero_explicit() is accomplishing. Maybe I'm missing something here and
others may have different advice.

Thanks,
Tom

> 
> Regards,
> Thomas