Commit-ID: 796038799a72adb279d785c9154df6eeb98b6e8d Gitweb: http://git.kernel.org/tip/796038799a72adb279d785c9154df6eeb98b6e8d Author: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> AuthorDate: Wed, 16 May 2012 13:22:41 -0700 Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> CommitDate: Wed, 16 May 2012 13:22:41 -0700 x86, realmode: Mask out EFER.LMA when saving trampoline EFER Some AMD processors apparently #GP(0) if EFER.LMA is set in WRMSR, rather than ignoring it. Thus, we need to mask it out. Reported-by: Ingo Molnar <mingo@xxxxxxxxxx> Tested-by: Borislav Petkov <bp@xxxxxxxxx> Cc: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxx> Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1336501366-28617-24-git-send-email-jarkko.sakkinen@xxxxxxxxx --- 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 66ac276..0992779 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; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|