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x86/microcode: Do the family check first

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On CPUs like AMD's Geode, for example, we shouldn't even try to load
microcode because they do not support the modern microcode loading
interface.

However, we do the family check *after* the other checks whether the
loader has been disabled on the command line or whether we're running in
a guest.

So move the family checks first in order to exit early if we're being
loaded on an unsupported family.

Reported-and-tested-by: Sven Glodowski <glodi1@arcor.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 4.11..
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://bugzilla.suse.com/show_bug.cgi?id=1061396
Link: http://lkml.kernel.org/r/20171012112316.977-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov 2017-10-12 13:23:16 +02:00 committed by Ingo Molnar
parent b956575bed
commit 1f161f67a2
1 changed files with 18 additions and 9 deletions
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27
arch/x86/kernel/cpu/microcode/core.c
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@ -122,9 +122,6 @@ static bool __init check_loader_disabled_bsp(void)
bool *res = &dis_ucode_ldr;
#endif
if (!have_cpuid_p())
return *res;
/*
* CPUID(1).ECX[31]: reserved for hypervisor use. This is still not
* completely accurate as xen pv guests don't see that CPUID bit set but
@ -166,24 +163,36 @@ bool get_builtin_firmware(struct cpio_data *cd, const char *name)
void __init load_ucode_bsp(void)
{
unsigned int cpuid_1_eax;
bool intel = true;
if (check_loader_disabled_bsp())
if (!have_cpuid_p())
return;
cpuid_1_eax = native_cpuid_eax(1);
switch (x86_cpuid_vendor()) {
case X86_VENDOR_INTEL:
if (x86_family(cpuid_1_eax) >= 6)
load_ucode_intel_bsp();
if (x86_family(cpuid_1_eax) < 6)
return;
break;
case X86_VENDOR_AMD:
if (x86_family(cpuid_1_eax) >= 0x10)
load_ucode_amd_bsp(cpuid_1_eax);
if (x86_family(cpuid_1_eax) < 0x10)
return;
intel = false;
break;
default:
break;
return;
}
if (check_loader_disabled_bsp())
return;
if (intel)
load_ucode_intel_bsp();
else
load_ucode_amd_bsp(cpuid_1_eax);
}
static bool check_loader_disabled_ap(void)