From: Leo Yan <leo.yan@arm.com>
To: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Cc: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com,
catalin.marinas@arm.com, will@kernel.org,
alexandru.elisei@arm.com, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: arm64: Check cpu_has_spe() before initializing PMSCR_EL1 in VHE
Date: Wed, 8 Oct 2025 19:17:52 +0100 [thread overview]
Message-ID: <20251008181752.GD77665@e132581.arm.com> (raw)
In-Reply-To: <20251008165058.lcwiapdnar6hvw3b@hu-mojha-hyd.qualcomm.com>
On Wed, Oct 08, 2025 at 10:20:58PM +0530, Mukesh Ojha wrote:
[...]
> > > To me, this smells a lot more like some sort of papering over a
> > > firmware bug. Why isn't SPE available the first place?
> >
> > TF-a grants permission to non-secure world [1], only access from secure
> > world or realm will trap to EL3.
> >
> > So yes, it would be good to check if any issue in firmware.
>
> We have our own implementation of EL3 and not using TF-A.
If you don't fix your firmware, you won't be able to use Arm SPE with
the Linux kernel.
> I believe, we should check in a similar way as we are doing for nVHE
> case.
>
> if (host_data_test_flag(HAS_SPE))
> write_sysreg_el1(0, SYS_PMSCR);
The document Documentation/arch/arm64/booting.rst does not state that
permission for Arm SPE is mandatory, and the SPE driver [2] can
tolerate the lack of permission. So I'm fine with applying your patch
to fix the boot issue.
Thanks,
Leo
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/perf/arm_spe_pmu.c#n1084
next prev parent reply other threads:[~2025-10-08 18:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-07 18:23 [PATCH] KVM: arm64: Check cpu_has_spe() before initializing PMSCR_EL1 in VHE Mukesh Ojha
2025-10-07 18:31 ` Oliver Upton
2025-10-08 10:46 ` Marc Zyngier
2025-10-08 12:40 ` Leo Yan
2025-10-08 16:50 ` Mukesh Ojha
2025-10-08 18:17 ` Leo Yan [this message]
2025-10-08 18:26 ` Oliver Upton
2025-10-09 9:11 ` Suzuki K Poulose
2025-10-08 11:53 ` Mukesh Ojha
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=20251008181752.GD77665@e132581.arm.com \
--to=leo.yan@arm.com \
--cc=alexandru.elisei@arm.com \
--cc=catalin.marinas@arm.com \
--cc=joey.gouly@arm.com \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=mukesh.ojha@oss.qualcomm.com \
--cc=oliver.upton@linux.dev \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
--cc=yuzenghui@huawei.com \
/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).