61 lines
2.3 KiB
Diff
61 lines
2.3 KiB
Diff
SPDX-FileCopyrightText: 2022 Sean Christopherson <seanjc@google.com>
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SPDX-License-Identifier: GPL-2.0-only
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Revert the following patch:
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From ddfd117714014cebe7b5d008fdec8eaec620cba1 Mon Sep 17 00:00:00 2001
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From: Sean Christopherson <seanjc@google.com>
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Date: Wed, 30 Nov 2022 23:36:48 +0000
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Subject: [PATCH] x86/virt: Force GIF=1 prior to disabling SVM (for reboot
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flows)
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commit 6a3236580b0b1accc3976345e723104f74f6f8e6 upstream.
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Set GIF=1 prior to disabling SVM to ensure that INIT is recognized if the
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kernel is disabling SVM in an emergency, e.g. if the kernel is about to
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jump into a crash kernel or may reboot without doing a full CPU RESET.
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If GIF is left cleared, the new kernel (or firmware) will be unabled to
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awaken APs. Eat faults on STGI (due to EFER.SVME=0) as it's possible
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that SVM could be disabled via NMI shootdown between reading EFER.SVME
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and executing STGI.
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Link: https://lore.kernel.org/all/cbcb6f35-e5d7-c1c9-4db9-fe5cc4de579a@amd.com
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Cc: stable@vger.kernel.org
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Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>
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Cc: Tom Lendacky <thomas.lendacky@amd.com>
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Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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Link: https://lore.kernel.org/r/20221130233650.1404148-3-seanjc@google.com
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Signed-off-by: Sean Christopherson <seanjc@google.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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arch/x86/include/asm/virtext.h | 16 +++++++++++++++-
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1 file changed, 15 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
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index 0116b2ee9e64f..4699acd602af4 100644
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--- arch/x86/include/asm/virtext.h
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+++ arch/x86/include/asm/virtext.h
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@@ -114,21 +114,7 @@ static inline void cpu_svm_disable(void)
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wrmsrl(MSR_VM_HSAVE_PA, 0);
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rdmsrl(MSR_EFER, efer);
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- if (efer & EFER_SVME) {
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- /*
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- * Force GIF=1 prior to disabling SVM to ensure INIT and NMI
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- * aren't blocked, e.g. if a fatal error occurred between CLGI
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- * and STGI. Note, STGI may #UD if SVM is disabled from NMI
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- * context between reading EFER and executing STGI. In that
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- * case, GIF must already be set, otherwise the NMI would have
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- * been blocked, so just eat the fault.
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- */
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- asm_volatile_goto("1: stgi\n\t"
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- _ASM_EXTABLE(1b, %l[fault])
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- ::: "memory" : fault);
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-fault:
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- wrmsrl(MSR_EFER, efer & ~EFER_SVME);
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- }
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+ wrmsrl(MSR_EFER, efer & ~EFER_SVME);
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}
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/** Makes sure SVM is disabled, if it is supported on the CPU
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