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Commit 1f161f67 authored by Borislav Petkov's avatar Borislav Petkov Committed by Ingo Molnar
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x86/microcode: Do the family check first 



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: default avatarSven Glodowski <glodi1@arcor.de>
Signed-off-by: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent b956575b

arch/x86/kernel/cpu/microcode/core.c

+18 −9
Original line number Diff line number Diff line
@@ -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)