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From: D Scott Phillips <scott@os.amperecomputing.com>
To: Oliver Upton <oliver.upton@linux.dev>, kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Darren Hart <darren@os.amperecomputing.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	stable@vger.kernel.org
Subject: Re: [PATCH 1/3] arm64: errata: Mitigate Ampere1 erratum AC03_CPU_38 at stage-2
Date: Wed, 14 Jun 2023 10:15:34 -0700	[thread overview]
Message-ID: <86sfauge2x.fsf@scott-ph-mail.amperecomputing.com> (raw)
In-Reply-To: <20230609220104.1836988-2-oliver.upton@linux.dev>

Oliver Upton <oliver.upton@linux.dev> writes:

> AmpereOne has an erratum in its implementation of FEAT_HAFDBS that
> required disabling the feature on the design. This was done by reporting
> the feature as not implemented in the ID register, although the
> corresponding control bits were not actually RES0. This does not align
> well with the requirements of the architecture, which mandates these
> bits be RES0 if HAFDBS isn't implemented.
>
> The kernel's use of stage-1 is unaffected, as the HA and HD bits are
> only set if HAFDBS is detected in the ID register. KVM, on the other
> hand, relies on the RES0 behavior at stage-2 to use the same value for
> VTCR_EL2 on any cpu in the system. Mitigate the non-RES0 behavior by
> leaving VTCR_EL2.HA clear on affected systems.
>
> Cc: stable@vger.kernel.org
> Cc: D Scott Phillips <scott@os.amperecomputing.com>
> Cc: Darren Hart <darren@os.amperecomputing.com>
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Acked-by: D Scott Phillips <scott@os.amperecomputing.com>

WARNING: multiple messages have this Message-ID (diff)
From: D Scott Phillips <scott@os.amperecomputing.com>
To: Oliver Upton <oliver.upton@linux.dev>, kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Darren Hart <darren@os.amperecomputing.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	stable@vger.kernel.org
Subject: Re: [PATCH 1/3] arm64: errata: Mitigate Ampere1 erratum AC03_CPU_38 at stage-2
Date: Wed, 14 Jun 2023 10:15:34 -0700	[thread overview]
Message-ID: <86sfauge2x.fsf@scott-ph-mail.amperecomputing.com> (raw)
In-Reply-To: <20230609220104.1836988-2-oliver.upton@linux.dev>

Oliver Upton <oliver.upton@linux.dev> writes:

> AmpereOne has an erratum in its implementation of FEAT_HAFDBS that
> required disabling the feature on the design. This was done by reporting
> the feature as not implemented in the ID register, although the
> corresponding control bits were not actually RES0. This does not align
> well with the requirements of the architecture, which mandates these
> bits be RES0 if HAFDBS isn't implemented.
>
> The kernel's use of stage-1 is unaffected, as the HA and HD bits are
> only set if HAFDBS is detected in the ID register. KVM, on the other
> hand, relies on the RES0 behavior at stage-2 to use the same value for
> VTCR_EL2 on any cpu in the system. Mitigate the non-RES0 behavior by
> leaving VTCR_EL2.HA clear on affected systems.
>
> Cc: stable@vger.kernel.org
> Cc: D Scott Phillips <scott@os.amperecomputing.com>
> Cc: Darren Hart <darren@os.amperecomputing.com>
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Acked-by: D Scott Phillips <scott@os.amperecomputing.com>

_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2023-06-14 17:15 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-09 22:01 [PATCH 0/3] KVM: arm64: Work around Ampere1 erratum AC03_CPU_38 Oliver Upton
2023-06-09 22:01 ` Oliver Upton
2023-06-09 22:01 ` [PATCH 1/3] arm64: errata: Mitigate Ampere1 erratum AC03_CPU_38 at stage-2 Oliver Upton
2023-06-09 22:01   ` Oliver Upton
2023-06-14 16:58   ` Catalin Marinas
2023-06-14 16:58     ` Catalin Marinas
2023-06-14 17:15   ` D Scott Phillips [this message]
2023-06-14 17:15     ` D Scott Phillips
2023-06-09 22:01 ` [PATCH 2/3] KVM: arm64: Refactor HFGxTR configuration into separate helpers Oliver Upton
2023-06-09 22:01   ` Oliver Upton
2023-06-09 22:01 ` [PATCH 3/3] KVM: arm64: Prevent guests from enabling HA/HD on Ampere1 Oliver Upton
2023-06-09 22:01   ` Oliver Upton
2023-06-14 16:57 ` [PATCH 0/3] KVM: arm64: Work around Ampere1 erratum AC03_CPU_38 Catalin Marinas
2023-06-14 16:57   ` Catalin Marinas
2023-06-14 23:06   ` Oliver Upton
2023-06-14 23:06     ` Oliver Upton
2023-06-15  8:36     ` Catalin Marinas
2023-06-15  8:36       ` Catalin Marinas
2023-06-15  9:51 ` Marc Zyngier
2023-06-15  9:51   ` Marc Zyngier
2023-06-20 13:15 ` Oliver Upton
2023-06-20 13:15   ` Oliver Upton

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