linux-kernel - Re: AMD microcode loading broken on 32 bit

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Date:	Tue, 28 Jan 2014 18:10:59 -0500
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: AMD microcode loading broken on 32 bit

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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