From nobody Tue Mar 3 05:05:26 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30FEF3E7146; Mon, 2 Mar 2026 19:14:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772478889; cv=none; b=q/FNOmBL06itnF/ao2r/A15NADnlqDBAK9cllT9v2kJ2K7UAabFsD7Asoj7iHk4WrzTTg8scM9gpaQWyE1+1ej/ESeivdcyyHd/Ts49QCYUKBSmhHEC1K6kGdKZfAfNCXDkQhEfQcEBnmkdGTWRgdChNV9tQSPpfvnBTFJgz0uQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772478889; c=relaxed/simple; bh=qAQttDEXuNN5uevUynuFwNEoZIIiao4qqyUzO8+IfTw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VkxkHgjwADDfhsa/Akv/F8PLiDml9L4pJ392pymqMY4wrbMAMGHDnRtNXYgzAU4Cl7Ssc1OF2u9/4nrtjnL1jyARNSqTtLZQfVhHKIxZBGxnDBxq8izKeLlnfjRkSBB+nelb5WsZJvyWSGQcbLtWrl+74llFYWFbmFEIIYaal/A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BT74g3Av; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BT74g3Av" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DED95C19423; Mon, 2 Mar 2026 19:14:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772478889; bh=qAQttDEXuNN5uevUynuFwNEoZIIiao4qqyUzO8+IfTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BT74g3AvvTBZdWue2nx3S10fGYbGqF7ZTO+PVZ3YMYF6yosRS8zrbCIyBQlIhojK4 uDsDRp2uoAVmQC0BD/4/sZm2wvmsUKHIQ2LlLEG2sWdbOxL1CmvzirW64pDWVhakUt r05VXWDKaDNFh+GySBBlMcNKwSUQehv8CwrRDMwv9g1cIF8LGw33or3KJmfOHXplar RD6SrMGKdmMf5+d5HC6IP9gpJy8nfuZ9gZvzSUV5ae3H6IjtFpfvnvl5QHbQccweh9 gyGu7fajujQOWlEP7Dj39C1Xm/xzohibTh3GZDIB2ByFTrxE4xSQV0YlcNjERDMi5j bkq1keD3IlxsA== From: Tycho Andersen To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Ashish Kalra , Tom Lendacky , John Allen , Herbert Xu , "David S. Miller" , Ard Biesheuvel , Neeraj Upadhyay , Kishon Vijay Abraham I , Alexey Kardashevskiy , Nikunj A Dadhania , "Peter Zijlstra (Intel)" , Kim Phillips , Sean Christopherson Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: [PATCH 08/11] x86/snp: allow disabling MFDM Date: Mon, 2 Mar 2026 12:13:31 -0700 Message-ID: <20260302191334.937981-9-tycho@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260302191334.937981-1-tycho@kernel.org> References: <20260302191334.937981-1-tycho@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Tycho Andersen (AMD)" The SNP x86 shutdown path needs to disable MFDM, since as the comment for k8_check_syscfg_dram_mod_en(), the "BIOS" is supposed clear it, or the kernel in the case of module unload and shutdown followed by kexec. Change this helper to allow for disabling it. Signed-off-by: Tycho Andersen (AMD) Reviewed-by: Tom Lendacky --- arch/x86/virt/svm/sev.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index 53bc0c7f2c50..cf984b8f4493 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -132,7 +132,7 @@ static unsigned long snp_nr_leaked_pages; #undef pr_fmt #define pr_fmt(fmt) "SEV-SNP: " fmt =20 -static void mfd_enable(void *arg) +static void mfd_reconfigure(void *arg) { u64 val; =20 @@ -141,7 +141,10 @@ static void mfd_enable(void *arg) =20 rdmsrq(MSR_AMD64_SYSCFG, val); =20 - val |=3D MSR_AMD64_SYSCFG_MFDM; + if (arg) + val |=3D MSR_AMD64_SYSCFG_MFDM; + else + val &=3D ~MSR_AMD64_SYSCFG_MFDM; =20 wrmsrq(MSR_AMD64_SYSCFG, val); } @@ -532,7 +535,7 @@ void snp_prepare_for_snp_init(void) * MtrrFixDramModEn is not shared between threads on a core, * therefore it must be set on all CPUs prior to enabling SNP. */ - on_each_cpu(mfd_enable, NULL, 1); + on_each_cpu(mfd_reconfigure, (void *)1, 1); =20 on_each_cpu(snp_enable, NULL, 1); =20 --=20 2.53.0