From: Mark Brown <broonie@kernel.org>
To: Leonardo Bras <leo.bras@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Shuah Khan <shuah@kernel.org>, Oliver Upton <oupton@kernel.org>,
Fuad Tabba <fuad.tabba@linux.dev>,
Peter Maydell <peter.maydell@linaro.org>,
Wei-Lin Chang <weilin.chang@arm.com>,
Yao Yuan <yaoyuan@linux.alibaba.com>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
kvmarm@lists.linux.dev, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v20 05/14] KVM: arm64: Set PSTATE.EXLOCK when entering an exception
Date: Thu, 3 Sep 2026 17:20:32 +0100 [thread overview]
Message-ID: <0c1c0d26-4e96-4076-8863-b4e871e38e67@sirena.org.uk> (raw)
In-Reply-To: <apmDRXBvS-XOi1NJ@LeoBrasDK>
[-- Attachment #1: Type: text/plain, Size: 1191 bytes --]
On Thu, Sep 03, 2026 at 03:25:09PM +0100, Leonardo Bras wrote:
> On Tue, Sep 01, 2026 at 10:47:03PM +0100, Mark Brown wrote:
> [...]
> > + /* When taking an exception to a higher EL EXLOCK is cleared. */
> > + if ((mode | PSR_MODE_THREAD_BIT) != target_mode)
> > + return 0;
> "Higher" is mentioned here, but the comparison is a "!=", so I suppose
> here we trust the fact that we always have "mode <= target_mode", and only
> 2 possible target exception levels (EL2h and EL1h).
> It's a nit, but maybe a "<" here would be more clear?
Sure.
> > + // PSTATE.EXLOCK is set to 0 upon any exception to a higher
> > + // EL, or to GCSCR_ELx.EXLOCKEN for an exception to the same
> > + // exception level. See ARM DDI 0487 R_WTXBY.
> > + new |= compute_exlock(vcpu, mode, target_mode);
> Same nit: am I really setting one bit here? or could be
> more stuff depending on the parameters? Having an "if (cond) new |= bit"
> seems more clear to what is being done, without needing to read the comment
> above.
The goal with the comment is to explain the rule that the code is
implementing in a style similar to all the other field updates in the
same function.
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
next prev parent reply other threads:[~2026-09-03 16:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 21:46 [PATCH v20 00/14] KVM: arm64: Provide guest support for GCS Mark Brown
2026-09-01 21:46 ` [PATCH v20 01/14] arm64/gcs: Ensure FGTs for EL1 GCS instructions are disabled Mark Brown
2026-09-03 16:10 ` Lorenzo Stoakes (ARM)
2026-09-01 21:47 ` [PATCH v20 02/14] KVM: arm64: Fix FGT mapping for HFGITR_EL2.nGCSEPP Mark Brown
2026-09-03 16:23 ` Lorenzo Stoakes (ARM)
2026-09-03 19:29 ` Mark Brown
2026-09-01 21:47 ` [PATCH v20 03/14] KVM: arm64: Manage GCS access and registers for guests Mark Brown
2026-09-02 16:44 ` Leonardo Bras
2026-09-03 20:52 ` Mark Brown
2026-09-03 18:13 ` Lorenzo Stoakes (ARM)
2026-09-03 20:41 ` Mark Brown
2026-09-01 21:47 ` [PATCH v20 04/14] KVM: arm64: Ensure GCS memory effects are visible Mark Brown
2026-09-02 16:30 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 05/14] KVM: arm64: Set PSTATE.EXLOCK when entering an exception Mark Brown
2026-09-03 14:25 ` Leonardo Bras
2026-09-03 16:20 ` Mark Brown [this message]
2026-09-03 16:40 ` Leonardo Bras
2026-09-01 21:47 ` [PATCH v20 06/14] KVM: arm64: Validate GCS exception lock when emulating ERET Mark Brown
2026-09-03 15:37 ` Leonardo Bras
2026-09-03 19:22 ` Mark Brown
2026-09-01 21:47 ` [PATCH v20 07/14] KVM: arm64: Forward GCS exceptions to nested guests Mark Brown
2026-09-01 21:47 ` [PATCH v20 08/14] KVM: arm64: Enforce EXLOCK for SPSR and ELR Mark Brown
2026-09-01 21:47 ` [PATCH v20 09/14] KVM: arm64: Allow GCS to be enabled for guests Mark Brown
2026-09-01 21:47 ` [PATCH v20 10/14] KVM: selftests: arm64: Add GCS registers to get-reg-list Mark Brown
2026-09-01 21:47 ` [PATCH v20 11/14] KVM: selftests: arm64: Add GCS to set_id_regs Mark Brown
2026-09-01 21:47 ` [PATCH v20 12/14] KVM: selftests: arm64: Only restore SPSR_EL1 and ELR_EL1 if they change Mark Brown
2026-09-01 21:47 ` [PATCH v20 13/14] tools: Synchronise the kernel esr.h Mark Brown
2026-09-01 21:47 ` [PATCH v20 14/14] KVM: selftests: arm64: Add GCS EXLOCK exception emulation test Mark Brown
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=0c1c0d26-4e96-4076-8863-b4e871e38e67@sirena.org.uk \
--to=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=fuad.tabba@linux.dev \
--cc=joey.gouly@arm.com \
--cc=kvmarm@lists.linux.dev \
--cc=leo.bras@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=maz@kernel.org \
--cc=oupton@kernel.org \
--cc=peter.maydell@linaro.org \
--cc=shuah@kernel.org \
--cc=suzuki.poulose@arm.com \
--cc=weilin.chang@arm.com \
--cc=will@kernel.org \
--cc=yaoyuan@linux.alibaba.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