On 12/19/16 02:56, tip-bot for Andy Lutomirski wrote:
> Commit-ID: 3df8d9208569ef0b2313e516566222d745f3b94b
> Gitweb: http://git.kernel.org/tip/3df8d9208569ef0b2313e516566222d745f3b94b
> Author: Andy Lutomirski <luto@xxxxxxxxxx>
> AuthorDate: Thu, 15 Dec 2016 10:14:42 -0800
> Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> CommitDate: Mon, 19 Dec 2016 11:50:24 +0100
>
> x86/cpu: Probe CPUID leaf 6 even when cpuid_level == 6
>
> A typo (or mis-merge?) resulted in leaf 6 only being probed if
> cpuid_level >= 7.
>
> Fixes: 2ccd71f1b278 ("x86/cpufeature: Move some of the scattered feature bits to x86_capability")
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> Acked-by: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Brian Gerst <brgerst@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/6ea30c0e9daec21e488b54761881a6dfcf3e04d0.1481825597.git.luto@xxxxxxxxxx
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> ---
> arch/x86/kernel/cpu/common.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index 1f6b50a..dc1697c 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -667,13 +667,14 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
> c->x86_capability[CPUID_1_EDX] = edx;
> }
>
> + /* Thermal and Power Management Leaf: level 0x00000006 (eax) */
> + if (c->cpuid_level >= 0x00000006)
> + c->x86_capability[CPUID_6_EAX] = cpuid_eax(0x00000006);
> +
> /* Additional Intel-defined flags: level 0x00000007 */
> if (c->cpuid_level >= 0x00000007) {
> cpuid_count(0x00000007, 0, &eax, &ebx, &ecx, &edx);
> -
> c->x86_capability[CPUID_7_0_EBX] = ebx;
> -
> - c->x86_capability[CPUID_6_EAX] = cpuid_eax(0x00000006);
> c->x86_capability[CPUID_7_ECX] = ecx;
> }
Perhaps we should have something like:
void cpuid_cond(u32 leaf, u32 subleaf,
u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
{
const struct cpuinfo_x86 *c = this_cpu_ptr(&cpu_info);
u32 maxleaf;
int cpuid_level = c->cpuid_level;
switch (leaf >> 16) {
case 0x0000:
maxleaf = c->cpuid_level;
break;
case 0x8000:
maxleaf = c->extended_cpuid_level;
break;
case 0x4000 .. 0x40ff:
/* Not ideal, can we do better? */
maxleaf = cpu_has(X86_FEATURE_HYPERVISOR)
? 0x40ffffff : 0;
break;
/* Add Transmeta 0x8086 and VIA/Cyrix 0xc000? */
default:
/* Can we do better? */
if (c->x86_vendor_id) == X86_VENDOR_INTEL)
maxleaf = 0;
else
maxleaf = leaf | 0xffff;
break;
}
if (cpuid_level >= 0 && leaf >= maxleaf) {
cpuid_count(leaf, subleaf, eax, ebx, ecx, edx);
} else {
*eax = *ebx = *ecx = *edx = 0;
}
}
-hpa
P.S. I would love to (a) move the CPUID bits into a structure instead of
passing all those crazy pointers around, and (b) stop passing struct
cpuinfo * around when we only use it for the current processor anyway (a
lot of these functions are in fact completely invalid if we don't); we
could define this_cpu_info as (*this_cpu_ptr(&cpu_info)) -- basically
what I have above -- or directly use percpu functions to access these
variables.
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