linux-kernel - Re: [PATCH v15 12/13] x86/kvmclock: Abort SecureTSC enabled guest when kvmclock is selected

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Message-ID: <20241230170453.GLZ3LStTw_bXGeiLnR@fat_crate.local>
Date: Mon, 30 Dec 2024 18:04:53 +0100
From: Borislav Petkov <bp@...en8.de>
To: Nikunj A Dadhania <nikunj@....com>
Cc: linux-kernel@...r.kernel.org, thomas.lendacky@....com, 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
Subject: Re: [PATCH v15 12/13] x86/kvmclock: Abort SecureTSC enabled guest
 when kvmclock is selected

On Tue, Dec 03, 2024 at 02:30:44PM +0530, Nikunj A Dadhania wrote:
> SecureTSC enabled guests should use TSC as the only clock source, terminate
> the guest with appropriate code when clock source switches to hypervisor
> controlled kvmclock.

This looks silly. Why not prevent kvm_register_clock() from succeeding simply
on a secure-TSC guest?

-- 
Regards/Gruss,
    Boris.

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