diff options
| -rw-r--r-- | arch/x86/kernel/realmode.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/x86/kernel/realmode.c b/arch/x86/kernel/realmode.c index 66ac276cf361..099277984b80 100644 --- a/arch/x86/kernel/realmode.c +++ b/arch/x86/kernel/realmode.c @@ -22,6 +22,7 @@ void __init setup_real_mode(void) size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); #ifdef CONFIG_X86_64 u64 *trampoline_pgd; + u32 efer_low, efer_high; #endif /* Has to be in very low memory so we can execute real-mode AP code. */ @@ -65,9 +66,13 @@ void __init setup_real_mode(void) trampoline_header->gdt_limit = __BOOT_DS + 7; trampoline_header->gdt_base = __pa(boot_gdt); #else - if (rdmsr_safe(MSR_EFER, &trampoline_header->efer_low, - &trampoline_header->efer_high)) - BUG(); + /* + * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR + * so we need to mask it out. + */ + rdmsr(MSR_EFER, efer_low, efer_high); + trampoline_header->efer_low = efer_low & ~EFER_LMA; + trampoline_header->efer_high = efer_high; trampoline_header->start = (u64) secondary_startup_64; trampoline_cr4_features = &trampoline_header->cr4; |