From: Catalin Marinas <catalin.marinas@arm.com>
To: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org, linux-kselftest@vger.kernel.org,
will@kernel.org, maz@kernel.org, oupton@kernel.org,
miko.lenczewski@arm.com, kevin.brodsky@arm.com,
broonie@kernel.org, ardb@kernel.org, suzuki.poulose@arm.com,
lpieralisi@kernel.org, joey.gouly@arm.com, yuzenghui@huawei.com
Subject: Re: (subset) [PATCH v17 0/8] support FEAT_LSUI
Date: Fri, 27 Mar 2026 17:18:31 +0000 [thread overview]
Message-ID: <aca75_16R1nnobb8@arm.com> (raw)
In-Reply-To: <acaMex3Pq13njdRt@e129823.arm.com>
On Fri, Mar 27, 2026 at 01:56:11PM +0000, Yeoreum Yun wrote:
> > I decided to drop patch [6/8] (arm64: armv8_deprecated: disable swp
> > emulation when FEAT_LSUI present). The way FEAT_LSUI support looks now,
> > we still have uaccess_enable_privileged() working properly and we could
> > even support SWP emulation using exclusives. While it's highly unlikely
> > to see both 32-bit EL0 and FEAT_LSUI in practice,
>
> This is one of decisive reason to drop the swp emulation with LSUI
> (https://lore.kernel.org/all/aXDbBKhE1SdCW6q4@willie-the-truck/)
Ah, I forgot about this discussion. It's a valid point, I just thought
it's unnecessary given that __uaccess_disable_hw_pan() still works.
If we want strict no PAN, I can add it back (really small patch). I
wonder whether we should also add a
WARN_ON_ONCE(cpus_have_final_cap(ARM64_HAS_LSUI)) to the pan disabling
function. Not urgent though.
--
Catalin
next prev parent reply other threads:[~2026-03-27 17:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-14 17:51 [PATCH v17 0/8] support FEAT_LSUI Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 1/8] arm64: cpufeature: add FEAT_LSUI Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 2/8] KVM: arm64: expose FEAT_LSUI to guest Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 3/8] KVM: arm64: kselftest: set_id_regs: add test for FEAT_LSUI Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 4/8] arm64: futex: refactor futex atomic operation Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 5/8] arm64: futex: support futex with FEAT_LSUI Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 6/8] arm64: armv8_deprecated: disable swp emulation when FEAT_LSUI present Yeoreum Yun
2026-03-14 17:51 ` [PATCH v17 7/8] KVM: arm64: use CAST instruction for swapping guest descriptor Yeoreum Yun
2026-03-17 11:04 ` Marc Zyngier
2026-03-14 17:51 ` [PATCH v17 8/8] arm64: Kconfig: add support for LSUI Yeoreum Yun
2026-03-27 13:16 ` (subset) [PATCH v17 0/8] support FEAT_LSUI Catalin Marinas
2026-03-27 13:56 ` Yeoreum Yun
2026-03-27 17:18 ` Catalin Marinas [this message]
2026-03-27 19:21 ` Catalin Marinas
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