diff options
Diffstat (limited to 'arch/x86/boot/compressed/head_64.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 7b5d36214352..f63ec254e457 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -642,12 +642,28 @@ SYM_CODE_START(trampoline_32bit_src) movl $MSR_EFER, %ecx rdmsr btsl $_EFER_LME, %eax + /* Avoid writing EFER if no change was made (for TDX guest) */ + jc 1f wrmsr - popl %edx +1: popl %edx popl %ecx +#ifdef CONFIG_X86_MCE + /* + * Preserve CR4.MCE if the kernel will enable #MC support. + * Clearing MCE may fault in some environments (that also force #MC + * support). Any machine check that occurs before #MC support is fully + * configured will crash the system regardless of the CR4.MCE value set + * here. + */ + movl %cr4, %eax + andl $X86_CR4_MCE, %eax +#else + movl $0, %eax +#endif + /* Enable PAE and LA57 (if required) paging modes */ - movl $X86_CR4_PAE, %eax + orl $X86_CR4_PAE, %eax testl %edx, %edx jz 1f orl $X86_CR4_LA57, %eax |