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Date: Mon, 2 Mar 2026 14:20:35 -0700
From: Tycho Andersen <tycho@kernel.org>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
	"H. Peter Anvin" <hpa@zytor.com>,
	Ashish Kalra <ashish.kalra@amd.com>,
	John Allen <john.allen@amd.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Ard Biesheuvel <ardb@kernel.org>,
	Alexey Kardashevskiy <aik@amd.com>,
	Nikunj A Dadhania <nikunj@amd.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Kim Phillips <kim.phillips@amd.com>,
	Sean Christopherson <seanjc@google.com>,
	linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: Re: [PATCH 09/11] x86/snp: create snp_x86_shutdown()
Message-ID: <aaX_I1QKxeAj7iY4@tycho.pizza>
References: <20260302191334.937981-1-tycho@kernel.org>
 <20260302191334.937981-10-tycho@kernel.org>
 <b3beeb84-51e3-46df-8b9b-8808f478c408@amd.com>
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In-Reply-To: <b3beeb84-51e3-46df-8b9b-8808f478c408@amd.com>

Hi Tom,

On Mon, Mar 02, 2026 at 02:35:38PM -0600, Tom Lendacky wrote:
> > +void snp_x86_shutdown(void)
> > +{
> 
> Would it make sense to check for SNP being enabled before calling the
> functions below? I realize each of the functions in question will do
> that, but it could save a bunch of IPI's with the on_each_cpu() if SNP
> is still enabled. Not a big deal either way, so:

It is guarded at the call site by:

        if (data.x86_snp_shutdown &&
            !WARN_ON_ONCE(syscfg & MSR_AMD64_SYSCFG_SNP_EN)) {
                if (!panic)
                        snp_x86_shutdown();

but we could push that into here to protect any future callers.

If we require a v2 I will make the fix.

> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>

Thanks for this and the others!

Tycho