[U-Boot] [PATCH v2 5/6] x86: Correct problems in the microcode loading

[Bin Meng]

Hi Simon,

On Tue, Dec 16, 2014 at 1:02 PM, Simon Glass <sjg at chromium.org> wrote:
> There are several problems in the code. The device tree decode is incorrect
> in ways that are masked due to a matching bug. Both are fixed. Also
> microcode_read_rev() should be inline and called before the microcode is
> written.
>
> Note: microcode writing does not work correctly on ivybridge for me. Further
> work is needed to resolve this. But this patch tidies up the existing code
> so that will be easier.

Yep, I noticed that with the new microcode.dtsi generated from the
microcode tool, the endianness is different from previous ivybridge
one. I think the new one is correct due to dts is using big-endian
while IA processor is little-endian. I just wonder why previous dtsi
could work on ivybridge? And now since we are using little-endian so
we should decode dts using little-endian too. Is this endianness issue
that causes the microcode writing does not work on ivybridge?

> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v2:
> - Add new patch to correct problems in the microcode loading
>
>  arch/x86/cpu/ivybridge/microcode_intel.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/cpu/ivybridge/microcode_intel.c b/arch/x86/cpu/ivybridge/microcode_intel.c
> index 79c075f..0817751 100644
> --- a/arch/x86/cpu/ivybridge/microcode_intel.c
> +++ b/arch/x86/cpu/ivybridge/microcode_intel.c
> @@ -50,17 +50,17 @@ static int microcode_decode_node(const void *blob, int node,
>         update->date_code = fdtdec_get_int(blob, node,
>                                            "intel,date-code", 0);
>         update->processor_signature = fdtdec_get_int(blob, node,
> -                                       "intel.processor-signature", 0);
> +                                       "intel,processor-signature", 0);
>         update->checksum = fdtdec_get_int(blob, node, "intel,checksum", 0);
>         update->loader_revision = fdtdec_get_int(blob, node,
> -                                                "loader-revision", 0);
> +                                                "intel,loader-revision", 0);
>         update->processor_flags = fdtdec_get_int(blob, node,
> -                                                "processor-flags", 0);
> +                                                "intel,processor-flags", 0);
>
>         return 0;
>  }
>
> -static uint32_t microcode_read_rev(void)
> +static inline uint32_t microcode_read_rev(void)
>  {
>         /*
>          * Some Intel CPUs can be very finicky about the CPUID sequence used.
> @@ -116,6 +116,7 @@ int microcode_update_intel(void)
>  {
>         struct microcode_update cpu, update;
>         const void *blob = gd->fdt_blob;
> +       int skipped;
>         int count;
>         int node;
>         int ret;
> @@ -123,12 +124,13 @@ int microcode_update_intel(void)
>         microcode_read_cpu(&cpu);
>         node = 0;
>         count = 0;
> +       skipped = 0;
>         do {
>                 node = fdtdec_next_compatible(blob, node,
>                                               COMPAT_INTEL_MICROCODE);
>                 if (node < 0) {
>                         debug("%s: Found %d updates\n", __func__, count);
> -                       return count ? 0 : -ENOENT;
> +                       return count ? 0 : skipped ? -EEXIST : -ENOENT;
>                 }
>
>                 ret = microcode_decode_node(blob, node, &update);
> @@ -137,12 +139,15 @@ int microcode_update_intel(void)
>                               ret);
>                         return ret;
>                 }
> -               if (update.processor_signature == cpu.processor_signature &&
> -                   (update.processor_flags & cpu.processor_flags)) {
> -                       debug("%s: Update already exists\n", __func__);
> -                       return -EEXIST;
> +               if (!(update.processor_signature == cpu.processor_signature &&
> +                     (update.processor_flags & cpu.processor_flags))) {
> +                       debug("%s: Skipping non-matching update, sig=%x, pf=%x\n",
> +                             __func__, update.processor_signature,
> +                             update.processor_flags);
> +                       skipped++;
> +                       continue;
>                 }
> -
> +               ret = microcode_read_rev();
>                 wrmsr(0x79, (ulong)update.data, 0);
>                 debug("microcode: updated to revision 0x%x date=%04x-%02x-%02x\n",
>                       microcode_read_rev(), update.date_code & 0xffff,
> --

Regards,
Bin