linux-kernel - Re: [PATCH v16 05/13] x86/sev: Add Secure TSC support for SNP guests

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250108084351.GCZ346x1QvK-gqj4sm@fat_crate.local>
Date: Wed, 8 Jan 2025 09:43:51 +0100
From: Borislav Petkov <bp@...en8.de>
To: "Nikunj A. Dadhania" <nikunj@....com>
Cc: Tom Lendacky <thomas.lendacky@....com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, kvm@...r.kernel.org, mingo@...hat.com,
	tglx@...utronix.de, dave.hansen@...ux.intel.com, pgonda@...gle.com,
	seanjc@...gle.com, pbonzini@...hat.com, francescolavra.fl@...il.com
Subject: Re: [PATCH v16 05/13] x86/sev: Add Secure TSC support for SNP guests

On Wed, Jan 08, 2025 at 02:07:07PM +0530, Nikunj A. Dadhania wrote:
> >>  void __init snp_secure_tsc_prepare(void)
> >>  {
> >> -	if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC))
> >> +	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP) ||
> >> +	    !cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC))
> > 
> > So how is moving the CC_ATTR_GUEST_SEV_SNP check here make any sense?
> 
> In the comment that you gave here[1], I understood that this check has 
> to be pushed to snp_secure_tsc_prepare().

The check should be pushed there but you should not check
CC_ATTR_GUEST_SEV_SNP *and* CC_ATTR_GUEST_SNP_SECURE_TSC if all you wanna do
is check if you're running a STSC guest. That was the whole point.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette