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x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes 

This doesn't refuse to load the affected microcodes; it just refuses to
use the Spectre v2 mitigation features if they're detected, by clearing
the appropriate feature bits.

The AMD CPUID bits are handled here too, because hypervisors *may* have
been exposing those bits even on Intel chips, for fine-grained control
of what's available.

It is non-trivial to use x86_match_cpu() for this table because that
doesn't handle steppings. And the approach taken in commit bd9240a18
almost made me lose my lunch.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: ak@linux.intel.com
Cc: ashok.raj@intel.com
Cc: dave.hansen@intel.com
Cc: karahmed@amazon.de
Cc: arjan@linux.intel.com
Cc: torvalds@linux-foundation.org
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: pbonzini@redhat.com
Cc: tim.c.chen@linux.intel.com
Cc: gregkh@linux-foundation.org
Link: https://lkml.kernel.org/r/1516896855-7642-7-git-send-email-dwmw@amazon.co.uk
hifive-unleashed-5.1
David Woodhouse 2018-01-25 16:14:14 +00:00 committed by Thomas Gleixner
parent fec9434a12
commit a5b2966364
1 changed files with 66 additions and 0 deletions
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66
arch/x86/kernel/cpu/intel.c
View File

@ -102,6 +102,59 @@ static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c)
ELF_HWCAP2 |= HWCAP2_RING3MWAIT;
}
/*
* Early microcode releases for the Spectre v2 mitigation were broken.
* Information taken from;
* - https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/microcode-update-guidance.pdf
* - https://kb.vmware.com/s/article/52345
* - Microcode revisions observed in the wild
* - Release note from 20180108 microcode release
*/
struct sku_microcode {
u8 model;
u8 stepping;
u32 microcode;
};
static const struct sku_microcode spectre_bad_microcodes[] = {
{ INTEL_FAM6_KABYLAKE_DESKTOP, 0x0B, 0x84 },
{ INTEL_FAM6_KABYLAKE_DESKTOP, 0x0A, 0x84 },
{ INTEL_FAM6_KABYLAKE_DESKTOP, 0x09, 0x84 },
{ INTEL_FAM6_KABYLAKE_MOBILE, 0x0A, 0x84 },
{ INTEL_FAM6_KABYLAKE_MOBILE, 0x09, 0x84 },
{ INTEL_FAM6_SKYLAKE_X, 0x03, 0x0100013e },
{ INTEL_FAM6_SKYLAKE_X, 0x04, 0x0200003c },
{ INTEL_FAM6_SKYLAKE_MOBILE, 0x03, 0xc2 },
{ INTEL_FAM6_SKYLAKE_DESKTOP, 0x03, 0xc2 },
{ INTEL_FAM6_BROADWELL_CORE, 0x04, 0x28 },
{ INTEL_FAM6_BROADWELL_GT3E, 0x01, 0x1b },
{ INTEL_FAM6_BROADWELL_XEON_D, 0x02, 0x14 },
{ INTEL_FAM6_BROADWELL_XEON_D, 0x03, 0x07000011 },
{ INTEL_FAM6_BROADWELL_X, 0x01, 0x0b000025 },
{ INTEL_FAM6_HASWELL_ULT, 0x01, 0x21 },
{ INTEL_FAM6_HASWELL_GT3E, 0x01, 0x18 },
{ INTEL_FAM6_HASWELL_CORE, 0x03, 0x23 },
{ INTEL_FAM6_HASWELL_X, 0x02, 0x3b },
{ INTEL_FAM6_HASWELL_X, 0x04, 0x10 },
{ INTEL_FAM6_IVYBRIDGE_X, 0x04, 0x42a },
/* Updated in the 20180108 release; blacklist until we know otherwise */
{ INTEL_FAM6_ATOM_GEMINI_LAKE, 0x01, 0x22 },
/* Observed in the wild */
{ INTEL_FAM6_SANDYBRIDGE_X, 0x06, 0x61b },
{ INTEL_FAM6_SANDYBRIDGE_X, 0x07, 0x712 },
};
static bool bad_spectre_microcode(struct cpuinfo_x86 *c)
{
int i;
for (i = 0; i < ARRAY_SIZE(spectre_bad_microcodes); i++) {
if (c->x86_model == spectre_bad_microcodes[i].model &&
c->x86_mask == spectre_bad_microcodes[i].stepping)
return (c->microcode <= spectre_bad_microcodes[i].microcode);
}
return false;
}
static void early_init_intel(struct cpuinfo_x86 *c)
{
u64 misc_enable;
@ -122,6 +175,19 @@ static void early_init_intel(struct cpuinfo_x86 *c)
if (c->x86 >= 6 && !cpu_has(c, X86_FEATURE_IA64))
c->microcode = intel_get_microcode_revision();
if ((cpu_has(c, X86_FEATURE_SPEC_CTRL) ||
cpu_has(c, X86_FEATURE_STIBP) ||
cpu_has(c, X86_FEATURE_AMD_SPEC_CTRL) ||
cpu_has(c, X86_FEATURE_AMD_PRED_CMD) ||
cpu_has(c, X86_FEATURE_AMD_STIBP)) && bad_spectre_microcode(c)) {
pr_warn("Intel Spectre v2 broken microcode detected; disabling SPEC_CTRL\n");
clear_cpu_cap(c, X86_FEATURE_SPEC_CTRL);
clear_cpu_cap(c, X86_FEATURE_STIBP);
clear_cpu_cap(c, X86_FEATURE_AMD_SPEC_CTRL);
clear_cpu_cap(c, X86_FEATURE_AMD_PRED_CMD);
clear_cpu_cap(c, X86_FEATURE_AMD_STIBP);
}
/*
* Atom erratum AAE44/AAF40/AAG38/AAH41:
*