From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Dave Hansen <dave.hansen@intel.com>, Borislav Petkov <bp@alien8.de>
Cc: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Isaku Yamahata <isaku.yamahata@intel.com>,
x86@kernel.org, linux-coco@lists.linux.dev,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH 1/2] x86/kexec: Preserve CR4.MCE during kexec
Date: Tue, 14 Feb 2023 02:48:35 +0300 [thread overview]
Message-ID: <20230213234836.3683-2-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <20230213234836.3683-1-kirill.shutemov@linux.intel.com>
TDX guests are not allowed to clear CR4.MCE. Attempt to clear it leads
to #VE.
Preserve the flag during kexec.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/kernel/relocate_kernel_64.S | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 4a73351f87f8..18f19dcc40e9 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -145,8 +145,12 @@ 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
+ * - Preserve MCE, if it was set. Clearing MCE may fault in some
+ * environments.
*/
- movl $X86_CR4_PAE, %eax
+ movq %cr4, %rax
+ andl $X86_CR4_MCE, %eax
+ orl $X86_CR4_PAE, %eax
testq $X86_CR4_LA57, %r13
jz 1f
orl $X86_CR4_LA57, %eax
--
2.39.1
next prev parent reply other threads:[~2023-02-13 23:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-13 23:48 [PATCH 0/2] Kexec enabling in TDX guest Kirill A. Shutemov
2023-02-13 23:48 ` Kirill A. Shutemov [this message]
2023-02-16 1:49 ` [PATCH 1/2] x86/kexec: Preserve CR4.MCE during kexec Edgecombe, Rick P
2023-02-16 9:43 ` Kirill A. Shutemov
2023-02-16 17:33 ` Edgecombe, Rick P
2023-02-16 19:46 ` Andrew Cooper
2023-02-13 23:48 ` [PATCH 2/2] x86/tdx: Convert shared memory back to private on kexec Kirill A. Shutemov
2023-02-15 1:53 ` Huang, Kai
2023-02-16 17:50 ` [PATCH 0/2] Kexec enabling in TDX guest Dave Hansen
2023-02-16 18:12 ` Kirill A. Shutemov
2023-02-16 18:32 ` Dave Hansen
2023-02-22 10:26 ` David Woodhouse
2023-02-24 14:30 ` Kirill A. Shutemov
2023-02-24 15:22 ` Dave Hansen
2023-02-24 16:12 ` Kirill A. Shutemov
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