Intel SPR erratum SPR4 says that if you trip into a vmexit while
doing FPU save/restore, your AMX register state might misbehave...
and by misbehave, I mean save all zeroes incorrectly, leading to
explosions if you restore it.
Since we're not using AMX for anything, the simple way to avoid
this is to just not save/restore those when we do anything, since
we're killing preemption of any sort across our save/restores.
If we ever decide to use AMX, it's not clear that we have any
way to mitigate this, on Linux...but I am not an expert.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes#14989Closes#15168
These are added:
- zfs_neon_available() for arm and aarch64
- zfs_sha256_available() for arm and aarch64
- zfs_sha512_available() for aarch64
- zfs_shani_available() for x86_64
Tested-by: Rich Ercolani <rincebrain@gmail.com>
Tested-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Co-Authored-By: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Closes#13741
As of the Linux 5.19 kernel the asm/fpu/internal.h header was
entirely removed. It has been effectively empty since the 5.16
kernel and provides no required functionality.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Attila Fülöp <attila@fueloep.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#13529
Commit 3b52ccd introduced a flaw where FSR and FSAVE are not restored
when using a Linux 5.16 kernel. These instructions are only used when
XSAVE is not supported by the processor meaning only some systems will
encounter this issue.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Attila Fülöp <attila@fueloep.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#13210Closes#13236
Cleanup the kernel SIMD code by removing kernel dependencies.
- Replace XSTATE_XSAVE with our own XSAVE implementation for all
kernels not exporting kernel_fpu{begin,end}(), see #13059
- Replace union fpregs_state by a uint8_t * buffer and get the size
of the buffer from the hardware via the CPUID instruction
- Replace kernels xgetbv() by our own implementation which was
already there for userspace.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes#13102
Observed when building on CentOS 8 Stream. Remove the `out`
label at the end of the function and instead return.
linux/simd_x86.h: In function 'kfpu_begin':
linux/simd_x86.h:337:1: error: label at end of compound statement
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Attila Fülöp <attila@fueloep.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#13089
Linux 5.16 moved XSTATE_XSAVE and XSTATE_XRESTORE out of our reach,
so add our own XSAVE{,OPT,S} code and use it for Linux 5.16.
Please note that this differs from previous behavior in that it
won't handle exceptions created by XSAVE an XRSTOR. This is sensible
for three reasons.
- Exceptions during XSAVE and XRSTOR can only occur if the feature
is not supported or enabled or the memory operand isn't aligned
on a 64 byte boundary. If this happens something else went
terribly wrong, and it may be better to stop execution.
- Previously we just printed a warning and didn't handle the fault,
this is arguable for the above reason.
- All other *SAVE instruction also don't handle exceptions, so this
at least aligns behavior.
Finally add a test to catch such a regression in the future.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes#13042Closes#13059
Linux 5.16 moved these functions into this new header in commit
1b4fb8545f2b00f2844c4b7619d64d98440a477c. This change adds code to look
for the presence of this header, and include it so that the code using
xgetbv & xsetbv will compile again.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes#12800
Currently SIMD accelerated AES-GCM performance is limited by two
factors:
a. The need to disable preemption and interrupts and save the FPU
state before using it and to do the reverse when done. Due to the
way the code is organized (see (b) below) we have to pay this price
twice for each 16 byte GCM block processed.
b. Most processing is done in C, operating on single GCM blocks.
The use of SIMD instructions is limited to the AES encryption of the
counter block (AES-NI) and the Galois multiplication (PCLMULQDQ).
This leads to the FPU not being fully utilized for crypto
operations.
To solve (a) we do crypto processing in larger chunks while owning
the FPU. An `icp_gcm_avx_chunk_size` module parameter was introduced
to make this chunk size tweakable. It defaults to 32 KiB. This step
alone roughly doubles performance. (b) is tackled by porting and
using the highly optimized openssl AES-GCM assembler routines, which
do all the processing (CTR, AES, GMULT) in a single routine. Both
steps together result in up to 32x reduction of the time spend in
the en/decryption routines, leading up to approximately 12x
throughput increase for large (128 KiB) blocks.
Lastly, this commit changes the default encryption algorithm from
AES-CCM to AES-GCM when setting the `encryption=on` property.
Reviewed-By: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-By: Jason King <jason.king@joyent.com>
Reviewed-By: Tom Caputi <tcaputi@datto.com>
Reviewed-By: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes#9749
fxsave and xsave require the target address to be 16-/64-byte aligned.
kmalloc(_node) does not (yet) offer such fine-grained control over
alignment[0,1], even though it does "the right thing" most of the time
for power-of-2 sizes. unfortunately, alignment is completely off when
using certain debugging or hardening features/configs, such as KASAN,
slub_debug=Z or the not-yet-upstream SLAB_CANARY.
Use alloc_pages_node() instead which allows us to allocate page-aligned
memory. Since fpregs_state is padded to a full page anyway, and this
code is only relevant for x86 which has 4k pages, this approach should
not allocate any unnecessary memory but still guarantee the needed
alignment.
0: https://lwn.net/Articles/787740/
1: https://lore.kernel.org/linux-block/20190826111627.7505-1-vbabka@suse.cz/
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#9608Closes#9674
Contrary to initial testing we cannot rely on these kernels to
invalidate the per-cpu FPU state and restore the FPU registers.
Nor can we guarantee that the kernel won't modify the FPU state
which we saved in the task struck.
Therefore, the kfpu_begin() and kfpu_end() functions have been
updated to save and restore the FPU state using our own dedicated
per-cpu FPU state variables.
This has the additional advantage of allowing us to use the FPU
again in user threads. So we remove the code which was added to
use task queues to ensure some functions ran in kernel threads.
Reviewed-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #9346Closes#9403
Move platform specific Linux headers under include/os/linux/.
Update the build system accordingly to detect the platform.
This lays some of the initial groundwork to supporting building
for other platforms.
As part of this change it was necessary to create both a user
and kernel space sys/simd.h header which can be included in
either context. No functional change, the source has been
refactored and the relevant #include's updated.
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Signed-off-by: Matthew Macy <mmacy@FreeBSD.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#9198
