From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
To: Mark Brown <broonie@kernel.org>
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>,
Leonardo Bras <leo.bras@arm.com>,
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 v21 15/15] KVM: selftests: arm64: Add GCS EXLOCK exception emulation test
Date: Thu, 1 Oct 2026 17:53:09 +0100 [thread overview]
Message-ID: <ar6PJqq3Ujaz-ibx@gremlin> (raw)
In-Reply-To: <20260930-arm64-gcs-v21-15-3556644cd927@kernel.org>
On Wed, Sep 30, 2026 at 10:48:25PM +0100, Mark Brown wrote:
> When running in vEL2 ERET is emulated, this means that we must emulate
> the behaviour of GCSCR_EL2.EXLOCKEN. Add a test that validates the
> behaviour.
>
> As per DDI0487 R_WTXBY PSTATE.EXLOCK is set to the value of
> GCSCR_ELx.EXLOCKEN when taking an exception to the same exception level.
> As per DDI0487 R_TYTWB if on exception return to the same EL
> GCSCR_ELx.EXLOCKEN is 1 and PSTATE.EXLOCK is not 1 then the exception
> return is illegal.
>
> We nest handling of two UDFs to allow us to both observe and modify
> PSTATE.EXLOCK, checking that expected exceptions are generated for ERET.
> We also repeat the UDF tests having enabled fine grained traps for ERET
> to try to ensure that the slow paths are taken.
>
> We also attempt to write to both SPSR_ELx and ELR_ELx, again using a UDF
> handler to control PSTATE.EXLOCK. We do all this both with and without
> having enabled EXLOCKEN, though only for code running at EL2 due to
> framework limitations.
>
> For completeness we also inject a data abort from EL0 to EL2 with
> GCSCR_EL2.EXLOCKEN set, ensuring that PSTATE.EXLOCK is not set.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> Reviewed-by: Leonardo Bras <leo.bras@arm.com>
This all seems reasonable test-wise, but I wonder if the discussion around 8/15
might alter some of what's tested here?
In that - if it's only hardware that's doing the locked check then the SPSR (and
probably ELR?) bits might only be exercising that rather than KVM stuff?
It might only need a comment update though :)
--
Cheers, Lorenzo
prev parent reply other threads:[~2026-10-01 16:53 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 21:48 [PATCH v21 00/15] KVM: arm64: Provide guest support for GCS Mark Brown
2026-09-30 21:48 ` [PATCH v21 01/15] arm64/gcs: Ensure FGTs for EL1 GCS instructions are disabled Mark Brown
2026-09-30 21:48 ` [PATCH v21 02/15] KVM: arm64: Refuse to start a guest with S1PIE or S1POE but not TCR2 Mark Brown
2026-09-30 22:05 ` sashiko-bot
2026-10-01 11:25 ` Lorenzo Stoakes (ARM)
2026-10-01 12:07 ` Mark Brown
2026-10-01 10:50 ` Lorenzo Stoakes (ARM)
2026-10-03 12:30 ` Marc Zyngier
2026-09-30 21:48 ` [PATCH v21 03/15] KVM: arm64: Manage GCS access and registers for guests Mark Brown
2026-10-01 11:28 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 04/15] KVM: arm64: Ensure GCS memory effects are visible Mark Brown
2026-09-30 21:48 ` [PATCH v21 05/15] KVM: arm64: Set PSTATE.EXLOCK when entering an exception Mark Brown
2026-10-01 11:37 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 06/15] KVM: arm64: Validate GCS exception lock when emulating ERET Mark Brown
2026-10-01 13:10 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 07/15] KVM: arm64: Forward GCS exceptions to nested guests Mark Brown
2026-10-01 14:25 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 08/15] KVM: arm64: Enforce EXLOCK for SPSR and ELR Mark Brown
2026-10-01 16:26 ` Lorenzo Stoakes (ARM)
2026-10-01 21:11 ` Mark Brown
2026-10-02 11:50 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 09/15] KVM: arm64: Allow GCS to be enabled for guests Mark Brown
2026-10-01 16:29 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 10/15] KVM: selftests: arm64: Check that invalid feature combinations are rejected Mark Brown
2026-10-01 16:35 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 11/15] KVM: selftests: arm64: Add GCS registers to get-reg-list Mark Brown
2026-10-01 16:36 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 12/15] KVM: selftests: arm64: Add GCS to set_id_regs Mark Brown
2026-10-01 16:38 ` Lorenzo Stoakes (ARM)
2026-10-01 18:14 ` Mark Brown
2026-10-02 11:27 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 13/15] KVM: selftests: arm64: Only restore SPSR_EL1 and ELR_EL1 if they change Mark Brown
2026-10-01 16:41 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 14/15] tools: Synchronise the kernel esr.h Mark Brown
2026-09-30 22:14 ` sashiko-bot
2026-10-01 16:47 ` Lorenzo Stoakes (ARM)
2026-10-01 17:27 ` Mark Brown
2026-10-02 11:31 ` Lorenzo Stoakes (ARM)
2026-09-30 21:48 ` [PATCH v21 15/15] KVM: selftests: arm64: Add GCS EXLOCK exception emulation test Mark Brown
2026-09-30 22:24 ` sashiko-bot
2026-10-01 16:53 ` Lorenzo Stoakes (ARM) [this message]
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