This is a note to let you know that I've just added the patch titled
x86/microcode: Do the family check first
to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-microcode-do-the-family-check-first.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1f161f67a272cc4f29f27934dd3f74cb657eb5c4 Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@xxxxxxx>
Date: Thu, 12 Oct 2017 13:23:16 +0200
Subject: x86/microcode: Do the family check first
From: Borislav Petkov <bp@xxxxxxx>
commit 1f161f67a272cc4f29f27934dd3f74cb657eb5c4 upstream.
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@xxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://bugzilla.suse.com/show_bug.cgi?id=1061396
Link: http://lkml.kernel.org/r/20171012112316.977-1-bp@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/microcode/core.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
--- 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
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_da
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)
Patches currently in stable-queue which might be from bp@xxxxxxx are
queue-4.13/x86-microcode-do-the-family-check-first.patch
queue-4.13/x86-alternatives-fix-alt_max_short-macro-to-really-be-a-max.patch
queue-4.13/ras-cec-use-the-right-length-for-cec_disable.patch