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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>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	James Morse <james.morse@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH v4 00/10] arm64: Add support for FEAT_E2H0, or lack thereof
Date: Fri, 2 Feb 2024 19:03:25 +0000	[thread overview]
Message-ID: <Zb08fXz23JUiF4hD@linux.dev> (raw)
In-Reply-To: <20240122181344.258974-1-maz@kernel.org>

On Mon, Jan 22, 2024 at 06:13:34PM +0000, Marc Zyngier wrote:
> Since ARMv8.1, the architecture has grown the VHE feature, which makes
> EL2 a superset of EL1. With ARMv9.5 (and retroactively allowed from
> ARMv8.1), the architecture allows implementations to have VHE as the
> *only* implemented behaviour, meaning that HCR_EL2.E2H can be
> implemented as RES1. As a follow-up, HCR_EL2.NV1 can also be
> implemented as RES0, making the VHE-ness of the architecture
> recursive.
> 
> This has a number of consequences, both at boot time and for KVM,
> though the changes at that level are pretty minor.
> 
> The real meat of this series is on the cpufeature front, as FEAT_E2H0
> is a *negative* feature, where 0b1111 (-1) represents E2H being RES1
> and 0b1110 (-2) additionally indicates that NV1 is RES0. Fun, isn't
> it?

This looks good to me. Catalin + Will, are you comfortable with the
cpufeature changes at this point?

No strong opinions on which tree these patches get applied to. Most of
the series is non-KVM code, so I'd understand if y'all wanted it to go
through arm64. OTOH, there are some other KVM features that might appear
in 6.9 that build on top of this, so at minimum I'd probably need a
shared branch.

LMK what you think.

-- 
Thanks,
Oliver

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  parent reply	other threads:[~2024-02-02 19:03 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-22 18:13 [PATCH v4 00/10] arm64: Add support for FEAT_E2H0, or lack thereof Marc Zyngier
2024-01-22 18:13 ` [PATCH v4 01/10] arm64: Add macro to compose a sysreg field value Marc Zyngier
2024-02-08 11:40   ` Catalin Marinas
2024-01-22 18:13 ` [PATCH v4 02/10] arm64: cpufeatures: Correctly handle signed values Marc Zyngier
2024-02-08 12:13   ` Catalin Marinas
2024-01-22 18:13 ` [PATCH v4 03/10] arm64: cpufeature: Correctly display signed override values Marc Zyngier
2024-02-08 12:14   ` Catalin Marinas
2024-01-22 18:13 ` [PATCH v4 04/10] arm64: sysreg: Add layout for ID_AA64MMFR4_EL1 Marc Zyngier
2024-02-08 12:25   ` Catalin Marinas
2024-02-08 13:06   ` Miguel Luis
2024-02-08 13:15     ` Marc Zyngier
2024-01-22 18:13 ` [PATCH v4 05/10] arm64: cpufeature: Add ID_AA64MMFR4_EL1 handling Marc Zyngier
2024-02-08 12:25   ` Catalin Marinas
2024-01-22 18:13 ` [PATCH v4 06/10] arm64: cpufeature: Detect HCR_EL2.NV1 being RES0 Marc Zyngier
2024-02-08 12:26   ` Catalin Marinas
2024-02-08 12:27   ` Catalin Marinas
2024-02-12 12:48   ` Marek Szyprowski
2024-02-12 14:00     ` Marc Zyngier
2024-02-12 14:21       ` Marek Szyprowski
2024-01-22 18:13 ` [PATCH v4 07/10] arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is negative Marc Zyngier
2024-02-08 12:27   ` Catalin Marinas
2024-01-22 18:13 ` [PATCH v4 08/10] KVM: arm64: Expose ID_AA64MMFR4_EL1 to guests Marc Zyngier
2024-01-22 18:13 ` [PATCH v4 09/10] KVM: arm64: Force guest's HCR_EL2.E2H RES1 when NV1 is not implemented Marc Zyngier
2024-01-22 18:13 ` [PATCH v4 10/10] KVM: arm64: Handle Apple M2 as not having HCR_EL2.NV1 implemented Marc Zyngier
2024-02-08 12:29   ` Catalin Marinas
2024-02-02 19:03 ` Oliver Upton [this message]
2024-02-08 12:30   ` [PATCH v4 00/10] arm64: Add support for FEAT_E2H0, or lack thereof Catalin Marinas
2024-02-08 15:24 ` Oliver Upton

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