From: Leonardo Bras <leonardo@linux.ibm.com>
To: "Desnes A. Nunes do Rosario" <desnesn@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Cc: gromero@linux.ibm.com
Subject: Re: [PATCH] powerpc: fix hardware PMU exception bug on PowerVM compatibility mode systems
Date: Sat, 15 Feb 2020 03:26:13 -0300 [thread overview]
Message-ID: <317f8594683d37ed7e0935d37f38e389eeae7b36.camel@linux.ibm.com> (raw)
In-Reply-To: <20200214001905.20065-1-desnesn@linux.ibm.com>
[-- Attachment #1: Type: text/plain, Size: 1509 bytes --]
Hello Desnes, thanks for the patch.
On Thu, 2020-02-13 at 21:19 -0300, Desnes A. Nunes do Rosario wrote:
> PowerVM systems running compatibility mode on a few Power8 revisions are
> still vulnerable to the hardware defect that loses PMU exceptions arriving
> prior to a context switch.
>
> The software fix for this issue is enabled through the CPU_FTR_PMAO_BUG
> cpu_feature bit, nevertheless this bit also needs to be set for PowerVM
> compatibility mode systems.
>
> Fixes: 68f2f0d431d9ea4 ("powerpc: Add a cpu feature CPU_FTR_PMAO_BUG")
> Signed-off-by: Desnes A. Nunes do Rosario <desnesn@linux.ibm.com>
> ---
> arch/powerpc/kernel/cputable.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
> index e745abc5457a..5bfef6263dfb 100644
> --- a/arch/powerpc/kernel/cputable.c
> +++ b/arch/powerpc/kernel/cputable.c
> @@ -2198,6 +2198,8 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset,
> if (old.oprofile_cpu_type != NULL) {
> t->oprofile_cpu_type = old.oprofile_cpu_type;
> t->oprofile_type = old.oprofile_type;
> + if (old.cpu_features & CPU_FTR_PMAO_BUG)
> + t->cpu_features |= CPU_FTR_PMAO_BUG;
> }
> }
>
What are your thoughts about doing:
t->cpu_features |= old.cpu_features & CPU_FTR_PMAO_BUG;
Also, I would recommend adding a short comment on top of the added
lines explaining why it is needed.
Best regards,
Leonardo Bras
[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2020-02-15 6:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 0:19 [PATCH] powerpc: fix hardware PMU exception bug on PowerVM compatibility mode systems Desnes A. Nunes do Rosario
2020-02-15 6:26 ` Leonardo Bras [this message]
2020-02-15 5:39 Leonardo Bras
2020-02-27 13:29 ` Desnes Augusto Nunes do Rosario
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=317f8594683d37ed7e0935d37f38e389eeae7b36.camel@linux.ibm.com \
--to=leonardo@linux.ibm.com \
--cc=desnesn@linux.ibm.com \
--cc=gromero@linux.ibm.com \
--cc=linuxppc-dev@lists.ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).