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 265F2848C for ; Fri, 10 Mar 2023 14:22:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CDA1C4339B; Fri, 10 Mar 2023 14:22:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678458127; bh=s7/xobAQRrsurvzSjHrXxO+rqxzENtSff3QKSZbLo/Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xbezsOkkPKmSUWzRYi8dCgzH8iaF9bPr60/SlfGECNJVGMPGHTKfe+qAx55v5z0m6 /Kzth+Oef+H6ec3GFcjZO/A4h4U1Do3GZn9PzEfG0P1ESpu7I4sbwMkZ3fBJWbhQEN QBrzufh1tQ/MTLphIOA7JUEgQUdq+t6TPb82iFh8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Cooper , Tom Lendacky , Thomas Gleixner , Sean Christopherson Subject: [PATCH 4.19 155/252] x86/virt: Force GIF=1 prior to disabling SVM (for reboot flows) Date: Fri, 10 Mar 2023 14:38:45 +0100 Message-Id: <20230310133723.510316289@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133718.803482157@linuxfoundation.org> References: <20230310133718.803482157@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Sean Christopherson commit 6a3236580b0b1accc3976345e723104f74f6f8e6 upstream. Set GIF=1 prior to disabling SVM to ensure that INIT is recognized if the kernel is disabling SVM in an emergency, e.g. if the kernel is about to jump into a crash kernel or may reboot without doing a full CPU RESET. If GIF is left cleared, the new kernel (or firmware) will be unabled to awaken APs. Eat faults on STGI (due to EFER.SVME=0) as it's possible that SVM could be disabled via NMI shootdown between reading EFER.SVME and executing STGI. Link: https://lore.kernel.org/all/cbcb6f35-e5d7-c1c9-4db9-fe5cc4de579a@amd.com Cc: stable@vger.kernel.org Cc: Andrew Cooper Cc: Tom Lendacky Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20221130233650.1404148-3-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/virtext.h | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) --- a/arch/x86/include/asm/virtext.h +++ b/arch/x86/include/asm/virtext.h @@ -114,7 +114,21 @@ static inline void cpu_svm_disable(void) wrmsrl(MSR_VM_HSAVE_PA, 0); rdmsrl(MSR_EFER, efer); - wrmsrl(MSR_EFER, efer & ~EFER_SVME); + if (efer & EFER_SVME) { + /* + * Force GIF=1 prior to disabling SVM to ensure INIT and NMI + * aren't blocked, e.g. if a fatal error occurred between CLGI + * and STGI. Note, STGI may #UD if SVM is disabled from NMI + * context between reading EFER and executing STGI. In that + * case, GIF must already be set, otherwise the NMI would have + * been blocked, so just eat the fault. + */ + asm_volatile_goto("1: stgi\n\t" + _ASM_EXTABLE(1b, %l[fault]) + ::: "memory" : fault); +fault: + wrmsrl(MSR_EFER, efer & ~EFER_SVME); + } } /** Makes sure SVM is disabled, if it is supported on the CPU