Re: AMD microcode loading broken on 32 bit

[Boris Ostrovsky]

On 01/28/2014 04:37 PM, Boris Ostrovsky wrote:
> On 01/28/2014 04:30 PM, Borislav Petkov wrote:
> > On Tue, Jan 28, 2014 at 04:05:20PM -0500, Boris Ostrovsky wrote:
> > > Yes. This was a bug in our build environment. It is fixed now but I
> > > put this bug back when I was testing your patch.
> > Right, that was the deal. Oh well, we'd need to verify the container
> > too, I guess:

The patch seems to have fixed the problem.

-boris

> I'll give it a spin. Apparently the problem is currently in 
> install_equiv_cpu_table()
> when we are trying to index into buf and buf (which is container) 
> doesn't appear
> to be there.
>
> Are you sure that
>
>     container = (u8 *)(__va((u32)relocated_ramdisk) +
>                            ((u32)container - 
> boot_params.hdr.ramdisk_image));
>
> in save_microcode_in_initrd_amd() always results in a valid pointer? 
> It is non-NULL but it
> points to address that looks to be not mapped.
>
> -boris
>
> > ---
> > diff --git a/arch/x86/kernel/cpu/microcode/amd_early.c 
> > b/arch/x86/kernel/cpu/microcode/amd_early.c
> > index 8384c0fa206f..c568b6c9af95 100644
> > --- a/arch/x86/kernel/cpu/microcode/amd_early.c
> > +++ b/arch/x86/kernel/cpu/microcode/amd_early.c
> > @@ -37,10 +37,12 @@ static __initdata char ucode_path[] = 
> > "kernel/x86/microcode/AuthenticAMD.bin";
> >     static struct cpio_data __init find_ucode_in_initrd(void)
> >   {
> > +    struct cpio_data ret;
> >       long offset = 0;
> >       char *path;
> >       void *start;
> >       size_t size;
> > +    u32 *hdr;
> >     #ifdef CONFIG_X86_32
> >       struct boot_params *p;
> > @@ -59,7 +61,18 @@ static struct cpio_data __init 
> > find_ucode_in_initrd(void)
> >       size    = boot_params.hdr.ramdisk_size;
> >   #endif
> >   -    return find_cpio_data(path, start, size, &offset);
> > +    ret = find_cpio_data(path, start, size, &offset);
> > +
> > +    /* Verify we didn't get some garbage from the initrd. */
> > +    hdr = (u32 *)ret.data;
> > +
> > +    if (hdr[0] != UCODE_MAGIC ||
> > +        hdr[1] != UCODE_EQUIV_CPU_TABLE_TYPE ||
> > +        hdr[2] == 0) {
> > +        ret.data = NULL;
> > +        ret.size = 0;
> > +    }
> > +    return ret;
> >   }
> >     static size_t compute_container_size(u8 *data, u32 total_size)
> > @@ -359,7 +372,7 @@ int __init save_microcode_in_initrd_amd(void)
> >           pr_info("microcode: updated early to new 
> > patch_level=0x%08x\n",
> >               ucode_new_rev);
> >   -    if (!container)
> > +    if (!container || !ucode_cpio.data)
> >           return -EINVAL;
> >         eax   = cpuid_eax(0x00000001);
> > --

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