Messages in this thread Patch in this message | | | From | "Huang, Kai" <> | Subject | Re: [PATCH 05/13] x86/kexec: Keep CR4.MCE set during kexec for TDX guest | Date | Mon, 9 Oct 2023 12:30:55 +0000 |
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On Thu, 2023-10-05 at 16:13 +0300, Kirill A. Shutemov wrote: > 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 environments.
Nit: non-TDX-guest environments. ?
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
> --- > 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..bea89814b48e 100644 > --- a/arch/x86/kernel/relocate_kernel_64.S > +++ b/arch/x86/kernel/relocate_kernel_64.S > @@ -145,11 +145,16 @@ 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 "jmp 1f", "", X86_FEATURE_TDX_GUEST > + orl $X86_CR4_MCE, %eax > 1: > movq %rax, %cr4 >
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