linux-stable.git/arch/x86/kernel/cpu/microcode/core.c, branch linux-3.16.y Linux kernel stable tree x86/microcode/AMD: Do not load when running on a hypervisor 2018-06-16T21:21:28+00:00 Borislav Petkov bp@suse.de 2016-12-18T16:44:13+00:00 904667f7fbb8c30d51c9b03f39c2d68d2bb301f2 commit a15a753539eca8ba243d576f02e7ca9c4b7d7042 upstream. Doing so is completely void of sense for multiple reasons so prevent it. Set dis_ucode_ldr to true and thus disable the microcode loader by default to address xen pv guests which execute the AP path but not the BSP path. By having it turned off by default, the APs won't run into the loader either. Also, check CPUID(1).ECX[31] which hypervisors set. Well almost, not the xen pv one. That one gets the aforementioned "fix". Also, improve the detection method by caching the final decision whether to continue loading in dis_ucode_ldr and do it once on the BSP. The APs then simply test that value. Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Acked-by: Juergen Gross <jgross@suse.com> Link: http://lkml.kernel.org/r/20161218164414.9649-4-bp@alien8.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Rolf Neugebauer <rolf.neugebauer@docker.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.16: - Early microcode loader is optional, so only set dis_ucode_ldr by default if it is enabled - Adjust context, filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a15a753539eca8ba243d576f02e7ca9c4b7d7042 upstream.

Doing so is completely void of sense for multiple reasons so prevent
it. Set dis_ucode_ldr to true and thus disable the microcode loader by
default to address xen pv guests which execute the AP path but not the
BSP path.

By having it turned off by default, the APs won't run into the loader
either.

Also, check CPUID(1).ECX[31] which hypervisors set. Well almost, not the
xen pv one. That one gets the aforementioned "fix".

Also, improve the detection method by caching the final decision whether
to continue loading in dis_ucode_ldr and do it once on the BSP. The APs
then simply test that value.

Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Juergen Gross <jgross@suse.com>
Link: http://lkml.kernel.org/r/20161218164414.9649-4-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rolf Neugebauer <rolf.neugebauer@docker.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16:
 - Early microcode loader is optional, so only set dis_ucode_ldr by default
   if it is enabled
 - Adjust context, filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
x86, microcode: Add a disable chicken bit 2014-05-21T03:21:27+00:00 Borislav Petkov bp@suse.de 2014-05-19T18:59:17+00:00 65cef1311d5d212fd3d48a43678536dc878ca288 Add a cmdline param which disables the microcode loader. This is useful mostly in debugging situations where we want to turn off microcode loading, both early from the initrd and late, as a means to be able to rule out its influence on the machine. Signed-off-by: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/1400525957-11525-3-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin <hpa@zytor.com> 
Add a cmdline param which disables the microcode loader. This is useful
mostly in debugging situations where we want to turn off microcode
loading, both early from the initrd and late, as a means to be able to
rule out its influence on the machine.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1400525957-11525-3-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
x86, microcode: Move to a proper location 2014-01-13T19:00:12+00:00 Borislav Petkov bp@suse.de 2013-12-01T17:09:58+00:00 bad5fa631fca5466401cd4a48e30cc1f1cb6101e We've grown a bunch of microcode loader files all prefixed with "microcode_". They should be under cpu/ because this is strictly CPU-related functionality so do that and drop the prefix since they're in their own directory now which gives that prefix. :) While at it, drop MICROCODE_INTEL_LIB config item and stash the functionality under CONFIG_MICROCODE_INTEL as it was its only user. Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com> 
We've grown a bunch of microcode loader files all prefixed with
"microcode_". They should be under cpu/ because this is strictly
CPU-related functionality so do that and drop the prefix since they're
in their own directory now which gives that prefix. :)

While at it, drop MICROCODE_INTEL_LIB config item and stash the
functionality under CONFIG_MICROCODE_INTEL as it was its only user.

Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>