Re: [PATCH 3.17 100/141] x86, microcode: Fix accessing dis_ucode_ldr on 32-bit

Boris Ostrovsky
2014-11-25T18:09:26Z

On 11/19/2014 03:52 PM, Greg Kroah-Hartman wrote:
> 3.17-stable review patch. If anyone has any objections, please let me know.

This breaks PV on Xen.

-boris

>
> ------------------
>
> From: Borislav Petkov <bp@suse.de>
>
> commit 85be07c32496dc264661308e4d9d4e9ccaff8072 upstream.
>
> We should be accessing it through a pointer, like on the BSP.
>
> Tested-by: Richard Hendershot <rshendershot@mchsi.com>
> Fixes: 65cef1311d5d ("x86, microcode: Add a disable chicken bit")
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> arch/x86/kernel/cpu/microcode/core_early.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/x86/kernel/cpu/microcode/core_early.c
> +++ b/arch/x86/kernel/cpu/microcode/core_early.c
> @@ -124,7 +124,7 @@ void __init load_ucode_bsp(void)
> static bool check_loader_disabled_ap(void)
> {
> #ifdef CONFIG_X86_32
> - return __pa_nodebug(dis_ucode_ldr);
> + return *((bool *)__pa_nodebug(&dis_ucode_ldr));
> #else
> return dis_ucode_ldr;
> #endif
>
>
> --
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