Currently, load_microcode_amd() iterates over all NUMA nodes, retrieves their
CPU masks and unconditionally accesses per-CPU data for the first CPU of each
mask.
According to Documentation/admin-guide/mm/numaperf.rst:
"Some memory may share the same node as a CPU, and others are provided as
memory only nodes."
Therefore, some node CPU masks may be empty and wouldn't have a "first CPU".
On a machine with far memory (and therefore CPU-less NUMA nodes):
- cpumask_of_node(nid) is 0
- cpumask_first(0) is CONFIG_NR_CPUS
- cpu_data(CONFIG_NR_CPUS) accesses the cpu_info per-CPU array at an
index that is 1 out of bounds
This does not have any security implications since flashing microcode is
a privileged operation but I believe this has reliability implications by
potentially corrupting memory while flashing a microcode update.
When booting with CONFIG_UBSAN_BOUNDS=y on an AMD machine that flashes
a microcode update. I get the following splat:
UBSAN: array-index-out-of-bounds in arch/x86/kernel/cpu/microcode/amd.c:X:Y
index 512 is out of range for type 'unsigned long[512]'
[...]
Call Trace:
dump_stack
__ubsan_handle_out_of_bounds
load_microcode_amd
request_microcode_amd
reload_store
kernfs_fop_write_iter
vfs_write
ksys_write
do_syscall_64
entry_SYSCALL_64_after_hwframe
Change the loop to go over only NUMA nodes which have CPUs before determining
whether the first CPU on the respective node needs microcode update.
[ bp: Massage commit message, fix typo. ]
Fixes: 7ff6edf4fe ("x86/microcode/AMD: Fix mixed steppings support")
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250310144243.861978-1-revest@chromium.org
Load patches for which the driver carries a SHA256 checksum of the patch
blob.
This can be disabled by adding "microcode.amd_sha_check=off" on the
kernel cmdline. But it is highly NOT recommended.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Instead of open-coding the check for size/data move it inside the
function and make it return a boolean indicating whether data was found
or not.
No functional changes.
[ bp: Write @ret in find_blobs_in_containers() only on success. ]
Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20241018155151.702350-2-nik.borisov@suse.com
This function should've been split a long time ago because it is used in
two paths:
1) On the late loading path, when the microcode is loaded through the
request_firmware interface
2) In the save_microcode_in_initrd() path which collects all the
microcode patches which are relevant for the current system before
the initrd with the microcode container has been jettisoned.
In that path, it is not really necessary to iterate over the nodes on
a system and match a patch however it didn't cause any trouble so it
was left for a later cleanup
However, that later cleanup was expedited by the fact that Jens was
enabling "Use L3 as a NUMA node" in the BIOS setting in his machine and
so this causes the NUMA CPU masks used in cpumask_of_node() to be
generated *after* 2) above happened on the first node. Which means, all
those masks were funky, wrong, uninitialized and whatnot, leading to
explosions when dereffing c->microcode in load_microcode_amd().
So split that function and do only the necessary work needed at each
stage.
Fixes: 94838d230a ("x86/microcode/AMD: Use the family,model,stepping encoded in the patch ID")
Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/91194406-3fdf-4e38-9838-d334af538f74@kernel.dk
Commit in Fixes changed how a microcode patch is loaded on Zen and newer but
the patch matching needs to happen with different rigidity, depending on what
is being done:
1) When the patch is added to the patches cache, the stepping must be ignored
because the driver still supports different steppings per system
2) When the patch is matched for loading, then the stepping must be taken into
account because each CPU needs the patch matching its exact stepping
Take care of that by making the matching smarter.
Fixes: 94838d230a ("x86/microcode/AMD: Use the family,model,stepping encoded in the patch ID")
Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/91194406-3fdf-4e38-9838-d334af538f74@kernel.dk
Initialize equiv_id in order to shut up:
arch/x86/kernel/cpu/microcode/amd.c:714:6: warning: variable 'equiv_id' is \
used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (x86_family(bsp_cpuid_1_eax) < 0x17) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
because clang doesn't do interprocedural analysis for warnings to see
that this variable won't be used uninitialized.
Fixes: 94838d230a ("x86/microcode/AMD: Use the family,model,stepping encoded in the patch ID")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407291815.gJBST0P3-lkp@intel.com/
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
On Zen and newer, the family, model and stepping is part of the
microcode patch ID so that the equivalence table the driver has been
using, is not needed anymore.
So switch the driver to use that from now on.
The equivalence table in the microcode blob should still remain in case
there's need to pass some additional information to the kernel loader.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240725112037.GBZqI1BbUk1KMlOJ_D@fat_crate.local
Older versions of clang show a warning for amd.c after a fix for a gcc
warning:
arch/x86/kernel/cpu/microcode/amd.c:478:47: error: format specifies type \
'unsigned char' but the argument has type 'u16' (aka 'unsigned short') [-Werror,-Wformat]
"amd-ucode/microcode_amd_fam%02hhxh.bin", family);
~~~~~~ ^~~~~~
%02hx
In clang-16 and higher, this warning is disabled by default, but clang-15 is
still supported, and it's trivial to avoid by adapting the types according
to the range of the passed data and the format string.
[ bp: Massage commit message. ]
Fixes: 2e9064facc ("x86/microcode/amd: Fix snprintf() format string warning in W=1 build")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240405204919.1003409-1-arnd@kernel.org
The AMD side of the loader issues the microcode revision for each
logical thread on the system, which can become really noisy on huge
machines. And doing that doesn't make a whole lot of sense - the
microcode revision is already in /proc/cpuinfo.
So in case one is interested in the theoretical support of mixed silicon
steppings on AMD, one can check there.
What is also missing on the AMD side - something which people have
requested before - is showing the microcode revision the CPU had
*before* the early update.
So abstract that up in the main code and have the BSP on each vendor
provide those revision numbers.
Then, dump them only once on driver init.
On Intel, do not dump the patch date - it is not needed.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/CAHk-=wg=%2B8rceshMkB4VnKxmRccVLtBLPBawnewZuuqyx5U=3A@mail.gmail.com
Applying microcode late can be fatal for the running kernel when the
update changes functionality which is in use already in a non-compatible
way, e.g. by removing a CPUID bit.
There is no way for admins which do not have access to the vendors deep
technical support to decide whether late loading of such a microcode is
safe or not.
Intel has added a new field to the microcode header which tells the
minimal microcode revision which is required to be active in the CPU in
order to be safe.
Provide infrastructure for handling this in the core code and a command
line switch which allows to enforce it.
If the update is considered safe the kernel is not tainted and the annoying
warning message not emitted. If it's enforced and the currently loaded
microcode revision is not safe for late loading then the load is aborted.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231017211724.079611170@linutronix.de
On CPUs where microcode loading is not NMI-safe the SMT siblings which
are parked in one of the play_dead() variants still react to NMIs.
So if an NMI hits while the primary thread updates the microcode the
resulting behaviour is undefined. The default play_dead() implementation on
modern CPUs is using MWAIT which is not guaranteed to be safe against
a microcode update which affects MWAIT.
Take the cpus_booted_once_mask into account to detect this case and
refuse to load late if the vendor specific driver does not advertise
that late loading is NMI safe.
AMD stated that this is safe, so mark the AMD driver accordingly.
This requirement will be partially lifted in later changes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115903.087472735@linutronix.de
Now that the microcode cache is initialized before the APs are brought
up, there is no point in scanning builtin/initrd microcode during AP
loading.
Convert the AP loader to utilize the cache, which in turn makes the CPU
hotplug callback which applies the microcode after initrd/builtin is
gone, obsolete as the early loading during late hotplug operations
including the resume path depends now only on the cache.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231017211723.243426023@linutronix.de
There is no reason to scan builtin/initrd microcode on each AP.
Cache the builtin/initrd microcode in an early initcall so that the
early AP loader can utilize the cache.
The existing fs initcall which invoked save_microcode_in_initrd_amd() is
still required to maintain the initrd_gone flag. Rename it accordingly.
This will be removed once the AP loader code is converted to use the
cache.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231017211723.187566507@linutronix.de
