From 1f161f67a272cc4f29f27934dd3f74cb657eb5c4 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Thu, 12 Oct 2017 13:23:16 +0200 Subject: [PATCH] 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: Sven Glodowski Signed-off-by: Borislav Petkov Cc: # 4.11.. Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner 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 --- arch/x86/kernel/cpu/microcode/core.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 86e8f0b2537b..c4fa4a85d4cb 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -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)