From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH 07/12] arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is non-zero
Date: Fri, 17 Nov 2023 10:01:20 -0800 [thread overview]
Message-ID: <ZVeqcPAW7qGj0RJ8@thinky-boi> (raw)
In-Reply-To: <86wmugzi96.wl-maz@kernel.org>
On Fri, Nov 17, 2023 at 12:17:25PM +0000, Marc Zyngier wrote:
> On Fri, 17 Nov 2023 00:23:13 +0000, Oliver Upton <oliver.upton@linux.dev> wrote:
> > Wouldn't it be more consistent with the architectural definition of
> > signed feature fields to just test the sign bit in this case?
> >
> > Maybe like:
> >
> > ubfx x0, x0, #ID_AA64MMFR4_EL1_E2H0_SHIFT, #ID_AA64MMFR4_EL1_E2H0_WIDTH
> > tbnz x0, #3, 1f
> >
> > You'll also save 8 measly bytes of text while you're at it :)
>
> At this stage, why not try this:
>
> tbnz x0, #(ID_AA64MMFR4_EL1_E2H0_SHIFT + ID_AA64MMFR4_EL1_E2H0_WIDTH - 1), 1f
>
> and we save a total of 12 bytes!
Ship it :)
--
Thanks,
Oliver
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next prev parent reply other threads:[~2023-11-17 18:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-13 17:42 [PATCH 00/12] arm64: Add support for FEAT_E2H0, or lack thereof Marc Zyngier
2023-11-13 17:42 ` [PATCH 01/12] arm64: cpufeatures: Correctly handle signed values Marc Zyngier
2023-11-17 0:45 ` Oliver Upton
2023-11-13 17:42 ` [PATCH 02/12] arm64: cpufeature: Correctly display signed override values Marc Zyngier
2023-11-17 0:46 ` Oliver Upton
2023-11-13 17:42 ` [PATCH 03/12] arm64: sysreg: Add layout for ID_AA64MMFR4_EL1 Marc Zyngier
2023-11-13 17:42 ` [PATCH 04/12] arm64: cpufeature: Add ID_AA64MMFR4_EL1 handling Marc Zyngier
2023-11-17 0:48 ` Oliver Upton
2023-11-13 17:42 ` [PATCH 05/12] arm64: cpufeature: Detect E2H0 not being implemented Marc Zyngier
2023-11-17 0:56 ` Oliver Upton
2023-11-17 12:21 ` Marc Zyngier
2023-11-13 17:42 ` [PATCH 06/12] arm64: cpufeature: Detect HCR_EL2.NV1 being RES0 Marc Zyngier
2023-11-13 17:42 ` [PATCH 07/12] arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is non-zero Marc Zyngier
2023-11-17 0:23 ` Oliver Upton
2023-11-17 12:17 ` Marc Zyngier
2023-11-17 18:01 ` Oliver Upton [this message]
2023-11-13 17:42 ` [PATCH 08/12] arm64: Add override for ID_AA64MMFR4_EL1.E2H0 Marc Zyngier
2023-11-13 17:42 ` [PATCH 09/12] arm64: Add MIDR-based override infrastructure Marc Zyngier
2023-11-13 17:42 ` [PATCH 10/12] arm64: Add MIDR-based overrides for ID_AA64MMFR4_EL1.E2H0 Marc Zyngier
2023-11-13 17:42 ` [PATCH 11/12] KVM: arm64: Expose ID_AA64MMFR4_EL1 to guests Marc Zyngier
2023-11-13 17:42 ` [PATCH 12/12] KVM: arm64: Force guest's HCR_EL2.E2H RES1 when NV1 is not implemented Marc Zyngier
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