commit da63865a01c6384d459464e5165d95d4f04878d8 upstream.

Commits 65cef1311d5d ("x86, microcode: Add a disable chicken bit") and
a18a0f6850d4 ("x86, microcode: Don't initialize microcode code on
paravirt") allow microcode driver skip initialization when microcode
loading is not permitted.

However, they don't prevent the driver from being loaded since the
init code returns 0. If at some point later the driver gets unloaded
this will result in an oops while trying to deregister the (never
registered) device.

To avoid this, make init code return an error on paravirt or when
microcode loading is disabled. The driver will then never be loaded.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: http://lkml.kernel.org/r/1422411669-25147-1-git-send-email-boris.ostrovsky@oracle.com
Reported-by: James Digwall <james@dingwall.me.uk>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit fbae4ba8c4a387e306adc9c710e5c225cece7678 upstream.

Normally, we do reapply microcode on resume. However, in the cases where
that microcode comes from the early loader and the late loader hasn't
been utilized yet, there's no easy way for us to go and apply the patch
applied during boot by the early loader.

Thus, reuse the patch stashed by the early loader for the BSP.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit a18a0f6850d4b286a5ebf02cd5b22fe496b86349 upstream.

Paravirtual guests are not expected to load microcode into processors
and therefore it is not necessary to initialize microcode loading
logic.

In fact, under certain circumstances initializing this logic may cause
the guest to crash. Specifically, 32-bit kernels use __pa_nodebug()
macro which does not work in Xen (the code path that leads to this macro
happens during resume when we call mc_bp_resume()->load_ucode_ap()
->check_loader_disabled_ap())

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: http://lkml.kernel.org/r/1417469264-31470-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

First, there was this: https://bugzilla.kernel.org/show_bug.cgi?id=88001

The problem there was that microcode patches are not being reapplied
after suspend-to-ram. It was important to reapply them, though, because
of for example Haswell's TSX erratum which disabled TSX instructions
with a microcode patch.

A simple fix was fb86b97300d9 ("x86, microcode: Update BSPs microcode
on resume") but, as it is often the case, simple fixes are too
simple. This one causes 32-bit resume to fail:

https://bugzilla.kernel.org/show_bug.cgi?id=88391

Properly fixing this would require more involved changes for which it
is too late now, right before the merge window. Thus, limit this to
64-bit only temporarily.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1417353999-32236-1-git-send-email-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

In the situation when we apply early microcode but do *not* apply late
microcode, we fail to update the BSP's microcode on resume because we
haven't initialized the uci->mc microcode pointer. So, in order to
alleviate that, we go and dig out the stashed microcode patch during
early boot. It is basically the same thing that is done on the APs early
during boot so do that too here.

Tested-by: alex.schnaidt@gmail.com
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=88001
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: <stable@vger.kernel.org> # v3.9
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20141118094657.GA6635@pd.tnic
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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>

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>