linux.git/arch/x86/kernel/cpu/microcode/amd.c, branch v4.11

x86/microcode/AMD: Remove struct cont_desc.eq_id

2017-01-23T09:02:51+00:00

The equivalence ID was needed outside of the container scanning logic
but now, after this has been cleaned up, not anymore. Now, cont_desc.mc
is used to denote whether the container we're looking at has the proper
microcode patch for this CPU or not.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/20170120202955.4091-17-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Remove AP scanning optimization

2017-01-23T09:02:51+00:00

The idea was to not scan the microcode blob on each AP (Application
Processor) during boot and thus save us some milliseconds. However, on
architectures where the microcode engine is shared between threads, this
doesn't work. Here's why:

The microcode on CPU0, i.e., the first thread, gets updated. The second
thread, i.e., CPU1, i.e., the first AP walks into load_ucode_amd_ap(),
sees that there's no container cached and goes and scans for the proper
blob.

It finds it and as a last step of apply_microcode_early_amd(), it tries
to apply the patch but that core has already the updated microcode
revision which it has received through CPU0's update. So it returns
false and we do desc->size = -1 to prevent other APs from scanning.

However, the next AP, CPU2, has a different microcode engine which
hasn't been updated yet. The desc->size == -1 test prevents it from
scanning the blob anew and we fail to update it.

The fix is much more straight-forward than it looks: the BSP
(BootStrapping Processor), i.e., CPU0, caches the microcode patch
in amd_ucode_patch. We use that on the AP and try to apply it.
In the 99.9999% of cases where we have homogeneous cores - *not*
mixed-steppings - the application will be successful and we're good to
go.

In the remaining small set of systems, we will simply rescan the blob
and find (or not, if none present) the proper patch and apply it then.

Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170120202955.4091-16-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Simplify saving from initrd

2017-01-23T09:02:50+00:00

No need to use the previously stashed info in the container - simply go
ahead and parse the initrd once more. It simplifies and streamlines the
code a whole lot.

Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170120202955.4091-15-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Unify load_ucode_amd_ap()

2017-01-23T09:02:50+00:00

Use a version for both bitness by adding a helper which does the actual
container finding and parsing which can be used on any CPU - BSP or AP.
Streamlines the paths more.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/20170120202955.4091-14-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Check patch level only on the BSP

2017-01-23T09:02:50+00:00

Check final patch levels for AMD only on the BSP. This way, we decide
early and only once whether to continue loading or to leave the loader
disabled on such systems.

Simplify a lot.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/20170120202955.4091-13-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Use find_microcode_in_initrd()

2017-01-23T09:02:48+00:00

Use the generic helper instead of semi-open-coding the procedure.

Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170120202955.4091-11-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Get rid of global this_equiv_id

2017-01-23T09:02:48+00:00

We have a container which we update/prepare each time before applying a
microcode patch instead of using a global.

Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170120202955.4091-10-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode: Decrease CPUID use

2017-01-23T09:02:47+00:00

Get CPUID(1).EAX value once per CPU and propagate value into the callers
instead of conveniently calling it every time.

Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170120202955.4091-9-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Rework container parsing

2017-01-23T09:02:47+00:00

It was pretty clumsy before and the whole work of parsing the microcode
containers was spread around the functions wrongly.

Clean it up so that there's a main scan_containers() function which
iterates over the microcode blob and picks apart the containers glued
together. For each container, it calls a parse_container() helper which
concentrates on one container only: sanity-checking, parsing, counting
microcode patches in there, etc.

It makes much more sense now and it is actually very readable. Oh, and
we luvz a diffstat removing more crap than adding.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/20170120202955.4091-8-bp@alien8.de
Signed-off-by: Thomas Gleixner

x86/microcode/AMD: Extend the container struct

2017-01-23T09:02:47+00:00

Make it into a container descriptor which is being passed around and
stores important info like the matching container and the patch for the
current CPU. Make it static too.

Later patches will use this and thus get rid of a double container
parsing.

Signed-off-by: Borislav Petkov 
Reviewed-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170120202955.4091-7-bp@alien8.de
Signed-off-by: Thomas Gleixner