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ddfd117714014cebe7b5d008fdec8eaec620cba1.patch (2435B)

    

  1. SPDX-FileCopyrightText: 2022 Sean Christopherson <seanjc@google.com>
  3. SPDX-License-Identifier: GPL-2.0-only
  5. Revert the following patch:
  6. From ddfd117714014cebe7b5d008fdec8eaec620cba1 Mon Sep 17 00:00:00 2001
  7. From: Sean Christopherson <seanjc@google.com>
  8. Date: Wed, 30 Nov 2022 23:36:48 +0000
  9. Subject: [PATCH] x86/virt: Force GIF=1 prior to disabling SVM (for reboot
  10.  flows)
  12. commit 6a3236580b0b1accc3976345e723104f74f6f8e6 upstream.
  14. Set GIF=1 prior to disabling SVM to ensure that INIT is recognized if the
  15. kernel is disabling SVM in an emergency, e.g. if the kernel is about to
  16. jump into a crash kernel or may reboot without doing a full CPU RESET.
  17. If GIF is left cleared, the new kernel (or firmware) will be unabled to
  18. awaken APs.  Eat faults on STGI (due to EFER.SVME=0) as it's possible
  19. that SVM could be disabled via NMI shootdown between reading EFER.SVME
  20. and executing STGI.
  22. Link: https://lore.kernel.org/all/cbcb6f35-e5d7-c1c9-4db9-fe5cc4de579a@amd.com
  23. Cc: stable@vger.kernel.org
  24. Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>
  25. Cc: Tom Lendacky <thomas.lendacky@amd.com>
  26. Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
  27. Link: https://lore.kernel.org/r/20221130233650.1404148-3-seanjc@google.com
  28. Signed-off-by: Sean Christopherson <seanjc@google.com>
  29. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30. ---
  31.  arch/x86/include/asm/virtext.h | 16 +++++++++++++++-
  32.  1 file changed, 15 insertions(+), 1 deletion(-)
  34. diff --git a/arch/x86/include/asm/virtext.h b/arch/x86/include/asm/virtext.h
  35. index 0116b2ee9e64f..4699acd602af4 100644
  36. --- linux-4.14.336/arch/x86/include/asm/virtext.h
  37. +++ linux-4.14.336/arch/x86/include/asm/virtext.h
  38. @@ -114,21 +114,7 @@ static inline void cpu_svm_disable(void)
  39.  
  40.  	wrmsrl(MSR_VM_HSAVE_PA, 0);
  41.  	rdmsrl(MSR_EFER, efer);
  42. -	if (efer & EFER_SVME) {
  43. -		/*
  44. -		 * Force GIF=1 prior to disabling SVM to ensure INIT and NMI
  45. -		 * aren't blocked, e.g. if a fatal error occurred between CLGI
  46. -		 * and STGI.  Note, STGI may #UD if SVM is disabled from NMI
  47. -		 * context between reading EFER and executing STGI.  In that
  48. -		 * case, GIF must already be set, otherwise the NMI would have
  49. -		 * been blocked, so just eat the fault.
  50. -		 */
  51. -		asm_volatile_goto("1: stgi\n\t"
  52. -				  _ASM_EXTABLE(1b, %l[fault])
  53. -				  ::: "memory" : fault);
  54. -fault:
  55. -		wrmsrl(MSR_EFER, efer & ~EFER_SVME);
  56. -	}
  57. +	wrmsrl(MSR_EFER, efer & ~EFER_SVME);
  58.  }
  59.  
  60.  /** Makes sure SVM is disabled, if it is supported on the CPU