From: Russell Currey <ruscur@russell.cc>
To: Benjamin Gray <bgray@linux.ibm.com>, linuxppc-dev@lists.ozlabs.org
Cc: npiggin@gmail.com
Subject: Re: [PATCH v2 03/12] powerpc/dexcr: Add initial Dynamic Execution Control Register (DEXCR) support
Date: Mon, 08 May 2023 13:44:11 +1000 [thread overview]
Message-ID: <38901b21426bb795dd26f081eb4908d86c779f90.camel@russell.cc> (raw)
In-Reply-To: <20230330055040.434133-4-bgray@linux.ibm.com>
On Thu, 2023-03-30 at 16:50 +1100, Benjamin Gray wrote:
> ISA 3.1B introduces the Dynamic Execution Control Register (DEXCR).
> It
> is a per-cpu register that allows control over various CPU behaviours
> including branch hint usage, indirect branch speculation, and
> hashst/hashchk support.
>
> Add some definitions and basic support for the DEXCR in the kernel.
> Right now it just
>
> * Zero initialises the DEXCR and HASHKEYR when a CPU onlines.
> * Clears them in reset_sprs().
> * Detects when the NPHIE aspect is supported (the others don't get
> looked at in this series, so there's no need to waste a CPU_FTR
> on them).
>
> We initialise the HASHKEYR to ensure that all cores have the same
> key,
> so an HV enforced NPHIE + swapping cores doesn't randomly crash a
> process using hash instructions. The stores to HASHKEYR are
> unconditional because the ISA makes no mention of the SPR being
> missing
> if support for doing the hashes isn't present. So all that would
> happen
> is the HASHKEYR value gets ignored. This helps slightly if NPHIE
> detection fails; e.g., we currently only detect it on pseries.
>
> Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
>
LGTM.
Reviewed-by: Russell Currey <ruscur@russell.cc>
next prev parent reply other threads:[~2023-05-08 3:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 5:50 [PATCH v2 00/12] Add static DEXCR support Benjamin Gray
2023-03-30 5:50 ` [PATCH v2 01/12] powerpc/book3s: Add missing <linux/sched.h> include Benjamin Gray
2023-05-08 3:36 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 02/12] powerpc/ptrace: Add missing <linux/regset.h> include Benjamin Gray
2023-05-08 3:39 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 03/12] powerpc/dexcr: Add initial Dynamic Execution Control Register (DEXCR) support Benjamin Gray
2023-05-08 3:44 ` Russell Currey [this message]
2023-03-30 5:50 ` [PATCH v2 04/12] powerpc/dexcr: Handle hashchk exception Benjamin Gray
2023-05-08 4:00 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 05/12] powerpc/dexcr: Support userspace ROP protection Benjamin Gray
2023-05-08 4:10 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 06/12] powerpc/dexcr: Support custom default DEXCR value Benjamin Gray
2023-05-08 4:24 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 07/12] powerpc/ptrace: Expose DEXCR and HDEXCR registers to ptrace Benjamin Gray
2023-05-08 4:30 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 08/12] powerpc/ptrace: Expose HASHKEYR register " Benjamin Gray
2023-05-08 4:32 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 09/12] Documentation: Document PowerPC kernel DEXCR interface Benjamin Gray
2023-05-08 4:40 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 10/12] selftests/powerpc: Add more utility macros Benjamin Gray
2023-05-08 4:43 ` Russell Currey
2023-03-30 5:50 ` [PATCH v2 11/12] selftests/powerpc/dexcr: Add hashst/hashchk test Benjamin Gray
2023-03-30 5:50 ` [PATCH v2 12/12] selftests/powerpc/dexcr: Add DEXCR status utility lsdexcr Benjamin Gray
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