On 23.03.2020 11:17, Andrew Cooper wrote:
> Implement a new get_ext_sigtable() helper to abstract the logic for
> identifying whether an extended signature table exists. As part of this,
> rename microcode_intel.bits to data and change its type so it can be usefully
> used in combination with the datasize header field.
>
> Also, replace the sigmatch() macro with a static inline with a more useful
> API, and an explanation of why it is safe to drop one of the previous
> conditionals.
>
> No practical change in behaviour.
>
> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
> ---
> CC: Jan Beulich <jbeul...@suse.com>
> CC: Wei Liu <w...@xen.org>
> CC: Roger Pau Monné <roger....@citrix.com>
> ---
> xen/arch/x86/cpu/microcode/intel.c | 75
> +++++++++++++++++++++++++-------------
> 1 file changed, 49 insertions(+), 26 deletions(-)
>
> diff --git a/xen/arch/x86/cpu/microcode/intel.c
> b/xen/arch/x86/cpu/microcode/intel.c
> index dfe44679be..bc3bbf139e 100644
> --- a/xen/arch/x86/cpu/microcode/intel.c
> +++ b/xen/arch/x86/cpu/microcode/intel.c
> @@ -61,7 +61,7 @@ struct microcode_header_intel {
>
> struct microcode_intel {
> struct microcode_header_intel hdr;
> - unsigned int bits[0];
> + uint8_t data[];
> };
>
> /* microcode format is extended from prescott processors */
> @@ -98,8 +98,41 @@ static uint32_t get_totalsize(const struct
> microcode_header_intel *hdr)
> return hdr->_totalsize ?: PPRO_UCODE_DATASIZE + MC_HEADER_SIZE;
> }
>
> -#define sigmatch(s1, s2, p1, p2) \
> - (((s1) == (s2)) && (((p1) & (p2)) || (((p1) == 0) && ((p2) == 0))))
> +/*
> + * A piece of microcode has an extended signature table if there is space
> + * between the end of data[] and the total size. (This logic also works
> + * appropriately for Pentium Pro/II microcode, which has 0 for both size
> + * fields, and no extended signature table.)
> + */
> +static const struct extended_sigtable *get_ext_sigtable(
> + const struct microcode_intel *mc)
> +{
> + if ( mc->hdr._totalsize > (MC_HEADER_SIZE + mc->hdr._datasize) )
> + return (void *)&mc->data[mc->hdr._datasize];
> +
> + return NULL;
> +}
> +
> +/*
> + * A piece of microcode is applicable for a CPU if:
> + * 1) the signatures (CPUID.1.EAX - Family/Model/Stepping) match, and
> + * 2) The Platform Flags bitmap intersect.
> + *
> + * A CPU will have a single Platform Flag bit, while the microcode may be
> + * common to multiple platforms and have multiple bits set.
> + *
> + * Note: The Pentium Pro/II microcode didn't use platform flags, and should
> + * treat 0 as a match. However, Xen being 64bit means that the cpu signature
> + * won't match, allowing us to simplify the logic.
> + */
> +static bool signature_maches(const struct cpu_signature *cpu_sig,
> + unsigned int ucode_sig, unsigned int ucode_pf)
I guess you've lost a 't' here and really mean signature_matches()?
If so with this taken care of
Reviewed-by: Jan Beulich <jbeul...@suse.com>
Jan
