lkml.org 
[lkml]   [2024]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCHv8 05/17] x86/kexec: Keep CR4.MCE set during kexec for TDX guest
Date
TDX guests are not allowed to clear CR4.MCE. Attempt to clear it leads
to #VE.

Use alternatives to keep the flag during kexec for TDX guests.

The change doesn't affect non-TDX-guest environments.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/relocate_kernel_64.S | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 56cab1bb25f5..e144bcf60cbe 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -5,6 +5,8 @@
*/

#include <linux/linkage.h>
+#include <linux/stringify.h>
+#include <asm/alternative.h>
#include <asm/page_types.h>
#include <asm/kexec.h>
#include <asm/processor-flags.h>
@@ -145,12 +147,15 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
* Set cr4 to a known state:
* - physical address extension enabled
* - 5-level paging, if it was enabled before
+ * - Machine check exception on TDX guest. Clearing MCE is not allowed
+ * in TDX guests.
*/
movl $X86_CR4_PAE, %eax
testq $X86_CR4_LA57, %r13
jz 1f
orl $X86_CR4_LA57, %eax
1:
+ ALTERNATIVE "", __stringify(orl $X86_CR4_MCE, %eax), X86_FEATURE_TDX_GUEST
movq %rax, %cr4

jmp 1f
--
2.43.0

\
 
 \ /
  Last update: 2024-05-27 15:25    [W:0.541 / U:0.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site