From mboxrd@z Thu Jan 1 00:00:00 1970 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 8A89531619D; Tue, 17 Mar 2026 16:23:22 +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=1773764602; cv=none; b=m3/8sBE08UQqfQb2uwQS3Ombl3H9T4VaGpBWIKiFxXo1T47j7S+SSOWNklAbbErTQmD4qYUWX9Hy+jQEvEBMgcvMSxm56+y7WSmPdGTCMAb4ykSRnvzaSIToS5M2gdMLh1Llv+9oVHWdXvtluuepv4JDFrPSp1XO7NIAkDbyADY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773764602; c=relaxed/simple; bh=XU6lMFg6u5MrLH5FDokrBVqlq/G8SBUCZxzvGtE3k+w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bCicByVgumaZxeTh+CYDv3nAu1ssmAv7W+wakXX3kfVLEJdj8c5VJkgGFrQg1A1hn9uJJkS1xO6wNdyUtRpZ3Z9puDqy9iSOrh8bcVVtnnS2ryBGiOIvjOHekyGg1xk2LKvNL4y7G4lK53l11Xnyf4do/Z/f9Pby7w0vlT7+xL0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qeVygaj+; 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="qeVygaj+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31DFDC4CEF7; Tue, 17 Mar 2026 16:23:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773764602; bh=XU6lMFg6u5MrLH5FDokrBVqlq/G8SBUCZxzvGtE3k+w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qeVygaj+LyUrVZcCyNdagGKreopjTZn7S4GYPQjfdoSxcoQI5WgMYzmRYWOtHz1I7 I20vhufey8HADCDgVI0lgI8RB4Cq0EC4jXb9vTqYl/+riahxt68+AzWkKQtej/ISto AFn+8xLrcHN0U9uKaF91OpHWCtVLQ99bWpjNhLO56TDyXucuseTKgPpITunjFslEFc asoRi4J1h6eEupL1fGteCjAq+BzBL2fdzubCNof4ePGeFtS8+Y3LeUpJvNb48yb5l0 6C5VKza3f/2ChsyXfCZrxp8gqT0ReKRbmt1LOnDzRgWH26cZduI2SwP5vBFhOJJEQg 6Qq41P61o/Wfw== 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, "Tycho Andersen (AMD)" Subject: [PATCH v3 3/7] x86/snp: create snp_x86_shutdown() Date: Tue, 17 Mar 2026 10:21:53 -0600 Message-ID: <20260317162157.150842-4-tycho@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260317162157.150842-1-tycho@kernel.org> References: <20260317162157.150842-1-tycho@kernel.org> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Tycho Andersen (AMD)" After SNP_SHUTDOWN, two architecture-level things should be done: 1. clear the RMP table 2. disable MFDM to prevent the FW_WARN in k8_check_syscfg_dram_mod_en() in the event of a kexec Create and export to the CCP driver a function that does them. Also change the MFDM helper to allow for disabling the bit, since the SNP x86 shutdown path needs to disable MFDM. The comment for k8_check_syscfg_dram_mod_en() notes, the "BIOS" is supposed clear it, or the kernel in the case of module unload and shutdown followed by kexec. Signed-off-by: Tycho Andersen (AMD) Reviewed-by: Tom Lendacky --- arch/x86/include/asm/sev.h | 2 ++ arch/x86/virt/svm/sev.c | 23 ++++++++++++++++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 0bcd89d4fe90..36d2b1ea19c0 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -662,6 +662,7 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages) __snp_leak_pages(pfn, pages, true); } void snp_prepare_for_snp_init(void); +void snp_x86_shutdown(void); #else static inline bool snp_probe_rmptable_info(void) { return false; } static inline int snp_rmptable_init(void) { return -ENOSYS; } @@ -679,6 +680,7 @@ static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} static inline void kdump_sev_callback(void) { } static inline void snp_fixup_e820_tables(void) {} static inline void snp_prepare_for_snp_init(void) {} +static inline void snp_x86_shutdown(void) {} #endif #endif diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index 88cb4a548701..85091d663f18 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -132,12 +132,15 @@ static unsigned long snp_nr_leaked_pages; #undef pr_fmt #define pr_fmt(fmt) "SEV-SNP: " fmt -static void mfd_enable(void *arg) +static void mfd_reconfigure(void *arg) { if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP)) return; - msr_set_bit(MSR_AMD64_SYSCFG, MSR_AMD64_SYSCFG_MFDM_BIT); + if (arg) + msr_set_bit(MSR_AMD64_SYSCFG, MSR_AMD64_SYSCFG_MFDM_BIT); + else + msr_clear_bit(MSR_AMD64_SYSCFG, MSR_AMD64_SYSCFG_MFDM_BIT); } static void snp_enable(void *arg) @@ -521,12 +524,26 @@ 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); on_each_cpu(snp_enable, NULL, 1); } EXPORT_SYMBOL_FOR_MODULES(snp_prepare_for_snp_init, "ccp"); +void snp_x86_shutdown(void) +{ + u64 syscfg; + + rdmsrq(MSR_AMD64_SYSCFG, syscfg); + + if (syscfg & MSR_AMD64_SYSCFG_SNP_EN) + return; + + clear_rmp(); + on_each_cpu(mfd_reconfigure, 0, 1); +} +EXPORT_SYMBOL_FOR_MODULES(snp_x86_shutdown, "ccp"); + /* * Do the necessary preparations which are verified by the firmware as * described in the SNP_INIT_EX firmware command description in the SNP -- 2.53.0