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Shutemov" To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "Rafael J. Wysocki" , Peter Zijlstra , Adrian Hunter , Kuppuswamy Sathyanarayanan , Elena Reshetova , Jun Nakajima , Rick Edgecombe , Tom Lendacky , "Kalra, Ashish" , Sean Christopherson , "Huang, Kai" , Baoquan He , kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv10 05/18] x86/kexec: Keep CR4.MCE set during kexec for TDX guest Date: Tue, 9 Apr 2024 14:29:57 +0300 Message-ID: <20240409113010.465412-6-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240409113010.465412-1-kirill.shutemov@linux.intel.com> References: <20240409113010.465412-1-kirill.shutemov@linux.intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Depending on setup, TDX guests might be 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 --- arch/x86/kernel/relocate_kernel_64.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index 56cab1bb25f5..8e2037d78a1f 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -5,6 +5,8 @@ */ #include +#include +#include #include #include #include @@ -145,11 +147,17 @@ 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, if it was enabled before. + * Clearing MCE might not allowed in TDX guests, depending on setup. */ movl $X86_CR4_PAE, %eax testq $X86_CR4_LA57, %r13 jz 1f orl $X86_CR4_LA57, %eax +1: + testq $X86_CR4_MCE, %r13 + jz 1f + ALTERNATIVE "", __stringify(orl $X86_CR4_MCE, %eax), X86_FEATURE_TDX_GUEST 1: movq %rax, %cr4 -- 2.43.0