On Wed, Nov 15, 2023 at 03:00:36PM +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-guest environments. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> > --- > 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: ALTERNATIVE "", "orl $X86_CR4_MCE, %eax", X86_FEATURE_TDX_GUEST ? > movq %rax, %cr4 > > -- > 2.41.0 > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
