Re: [PATCH] x86, amd_ucode: Safeguard against #GP

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 05/21/2014 05:28 PM, Aravind Gopalakrishnan wrote:
> When HW tries to load a corrupted patch, it generates #GP
> and hangs the system. Use wrmsr_safe instead so that we
> fail to load microcode gracefully.
>
> Example on a Fam15h system-
> (XEN) microcode: CPU0 collect_cpu_info: patch_id=0x6000626
> (XEN) microcode: CPU0 size 7870, block size 2586 offset 76 equivID
> 0x6012 rev 0x6000637
> (XEN) microcode: CPU0 found a matching microcode update with version
> 0x6000637 (current=0x6000626)
> (XEN) traps.c:3073: GPF (0000): ffff82d08016f682 -> ffff82d08022d9f8
> (XEN) microcode: CPU0 update from revision 0x6000637 to 0x6000626 failed
>
> Signed-off-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

> ---
>   xen/arch/x86/microcode_amd.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c
> index e83f4b6..23637e2 100644
> --- a/xen/arch/x86/microcode_amd.c
> +++ b/xen/arch/x86/microcode_amd.c
> @@ -191,7 +191,7 @@ static int apply_microcode(int cpu)
>   
>       spin_lock_irqsave(&microcode_update_lock, flags);
>   
> -    wrmsrl(MSR_AMD_PATCHLOADER, (unsigned long)hdr);
> +    wrmsr_safe(MSR_AMD_PATCHLOADER, (unsigned long)hdr);
>   
>       /* get patch id after patching */
>       rdmsrl(MSR_AMD_PATCHLEVEL, rev);