From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Hector Martin <marcan@marcan.st>, Arnd Bergmann <arnd@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH 1/2] arm64: cpufeature: Allow early filtering of feature override
Date: Thu, 25 Mar 2021 19:27:59 +0000 [thread overview]
Message-ID: <20210325192759.GA16123@willie-the-truck> (raw)
In-Reply-To: <20210325124721.941182-2-maz@kernel.org>
On Thu, Mar 25, 2021 at 12:47:20PM +0000, Marc Zyngier wrote:
> Some CPUs are broken enough that some overrides need to be rejected
> at the earliest opportunity. In some cases, that's right at cpu
> feature override time.
>
> Provide the necessary infrastructure to filter out overrides,
> and to report such filtered out overrides to the core cpufeature code.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/kernel/cpufeature.c | 6 ++++++
> arch/arm64/kernel/idreg-override.c | 13 +++++++++++++
> 2 files changed, 19 insertions(+)
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 066030717a4c..6de15deaa912 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -809,6 +809,12 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new)
> reg->name,
> ftrp->shift + ftrp->width - 1,
> ftrp->shift, str, tmp);
> + } else if ((ftr_mask & reg->override->val) == ftr_mask) {
This seems to rely on 'val == mask' being invalid, but I'm not sure why
that's generally true. Can we just invoke the filter function again here to
figure out if the field has been ignored? Then in match_options, we can just
clear the override val/mask to zero.
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-25 19:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-25 12:47 [PATCH 0/2] arm64: Dealing with VHE-only CPUs Marc Zyngier
2021-03-25 12:47 ` [PATCH 1/2] arm64: cpufeature: Allow early filtering of feature override Marc Zyngier
2021-03-25 19:27 ` Will Deacon [this message]
2021-03-26 10:56 ` Marc Zyngier
2021-03-29 10:21 ` Will Deacon
2021-03-25 12:47 ` [PATCH 2/2] arm64: Cope with CPUs stuck in VHE mode Marc Zyngier
2021-03-25 19:33 ` Will Deacon
2021-03-26 11:20 ` Marc Zyngier
2021-03-29 10:22 ` Will Deacon
2021-03-30 17:00 ` Marc Zyngier
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=20210325192759.GA16123@willie-the-truck \
--to=will@kernel.org \
--cc=arnd@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=kernel-team@android.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=marcan@marcan.st \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.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