SPDX-FileCopyrightText: 2022 Sean Christopherson SPDX-License-Identifier: GPL-2.0-only Revert the following patch: From ddfd117714014cebe7b5d008fdec8eaec620cba1 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 30 Nov 2022 23:36:48 +0000 Subject: [PATCH] x86/virt: Force GIF=1 prior to disabling SVM (for reboot flows) 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(-) diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h index 0116b2ee9e64f..4699acd602af4 100644 --- arch/x86/include/asm/virtext.h +++ arch/x86/include/asm/virtext.h @@ -114,21 +114,7 @@ static inline void cpu_svm_disable(void) wrmsrl(MSR_VM_HSAVE_PA, 0); rdmsrl(MSR_EFER, efer); - 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); - } + wrmsrl(MSR_EFER, efer & ~EFER_SVME); } /** Makes sure SVM is disabled, if it is supported on the CPU