From: Oliver Upton <oliver.upton@linux.dev>
To: Fuad Tabba <tabba@google.com>
Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
maz@kernel.org, will@kernel.org, qperret@google.com,
seanjc@google.com, alexandru.elisei@arm.com,
catalin.marinas@arm.com, philmd@linaro.org, james.morse@arm.com,
suzuki.poulose@arm.com, mark.rutland@arm.com, broonie@kernel.org,
joey.gouly@arm.com, rananta@google.com, yuzenghui@huawei.com
Subject: Re: [PATCH v3 11/11] KVM: arm64: Drop sve_cond_update_zcr_vq_*
Date: Thu, 30 May 2024 13:14:40 -0700 [thread overview]
Message-ID: <ZljeMATYCy8yOesJ@linux.dev> (raw)
In-Reply-To: <ZljD8pu5Z5ujHny2@linux.dev>
On Thu, May 30, 2024 at 11:22:42AM -0700, Oliver Upton wrote:
> Hi,
>
> On Tue, May 28, 2024 at 01:59:14PM +0100, Fuad Tabba wrote:
> > The conditional update likely doesn't help performance, but makes
> > the code a bit more difficult to read. Remove these macros and
> > just write directly to ZCR.
> >
> > Signed-off-by: Fuad Tabba <tabba@google.com>
> > ---
> > This patch is meant as an RFC, and undoes the previous patch.
> > Please feel free to accept/drop whichever patches you think make
> > sense.
>
> The motivation behind this helper is to avoid unnecessary synchronizing
> behavior, since as you note the architecture does not require
> explicit synchronization for the value to become visible to subsequent
> instructions.
*indirect reads from subsequent instructions :)
--
Thanks,
Oliver
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next prev parent reply other threads:[~2024-05-30 20:15 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-28 12:59 [PATCH v3 00/11] KVM: arm64: Fix handling of host fpsimd/sve state in protected mode Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 01/11] KVM: arm64: Reintroduce __sve_save_state Fuad Tabba
2024-05-31 12:26 ` Mark Brown
2024-06-03 8:28 ` Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 02/11] KVM: arm64: Abstract set/clear of CPTR_EL2 bits behind helper Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 03/11] KVM: arm64: Specialize handling of host fpsimd state on trap Fuad Tabba
2024-05-31 13:35 ` Mark Brown
2024-05-28 12:59 ` [PATCH v3 04/11] KVM: arm64: Allocate memory mapped at hyp for host sve state in pKVM Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 05/11] KVM: arm64: Eagerly restore host fpsimd/sve " Fuad Tabba
2024-05-31 14:09 ` Mark Brown
2024-06-03 8:37 ` Fuad Tabba
2024-06-03 13:27 ` Mark Brown
2024-06-03 13:48 ` Marc Zyngier
2024-06-03 14:15 ` Mark Brown
2024-06-03 14:31 ` Marc Zyngier
2024-05-28 12:59 ` [PATCH v3 06/11] KVM: arm64: Consolidate initializing the host data's fpsimd_state/sve " Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 07/11] KVM: arm64: Refactor CPACR trap bit setting/clearing to use ELx format Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 08/11] KVM: arm64: Add an isb before restoring guest sve state Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 09/11] KVM: arm64: Do not use sve_cond_update_zcr updating with ZCR_ELx_LEN_MASK Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 10/11] KVM: arm64: Do not perform an isb() if ZCR_EL2 isn't updated Fuad Tabba
2024-05-28 12:59 ` [PATCH v3 11/11] KVM: arm64: Drop sve_cond_update_zcr_vq_* Fuad Tabba
2024-05-30 18:22 ` Oliver Upton
2024-05-30 20:14 ` Oliver Upton [this message]
2024-05-31 6:40 ` Fuad Tabba
2024-05-28 13:13 ` [PATCH v3 00/11] KVM: arm64: Fix handling of host fpsimd/sve state in protected mode Fuad Tabba
2024-05-30 18:29 ` Oliver Upton
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