zfs/include/os
Rich Ercolani f288fdb4bd Avoid save/restoring AMX registers to avoid a SPR erratum
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 #14989
Closes #15168

Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
2024-04-03 16:39:43 -07:00
..
freebsd FreeBSD: catch up to __FreeBSD_version 1400093 2024-01-16 11:34:45 -08:00
linux Avoid save/restoring AMX registers to avoid a SPR erratum 2024-04-03 16:39:43 -07:00
Makefile.am Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00