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From: Oliver Upton <oliver.upton@linux.dev>
To: Will Deacon <will@kernel.org>
Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH 2/2] KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support
Date: Wed, 1 May 2024 17:47:40 +0000	[thread overview]
Message-ID: <ZjKAPHJEy_WAtjsg@linux.dev> (raw)
In-Reply-To: <20240501163400.15838-3-will@kernel.org>

On Wed, May 01, 2024 at 05:34:00PM +0100, Will Deacon wrote:
> The early command line parsing treats "kvm-arm.mode=protected" as an
> alias for "id_aa64mmfr1.vh=0", forcing the use of nVHE so that the host
> kernel runs at EL1 with the pKVM hypervisor at EL2.
> 
> With the introduction of hVHE support in ad744e8cb346 ("arm64: Allow
> arm64_sw.hvhe on command line"), the hypervisor can run using the EL2+0
> translation regime. This is interesting for unusual CPUs that have VH
> stuck to 1, but also because it opens the possibility of a hypervisor
> "userspace" in the distant future which could be used to isolate vCPU
> contexts in the hypervisor (see Marc's talk from KVM Forum 2022 [1]).
> 
> Repaint the "kvm-arm.mode=protected" alias to map to "arm64_sw.hvhe=1",
> which will use hVHE on CPUs that support it and remain with nVHE
> otherwise.
> 
> [1] https://www.youtube.com/watch?v=1F_Mf2j9eIo
> Signed-off-by: Will Deacon <will@kernel.org>

Acked-by: Oliver Upton <oliver.upton@linux.dev>

-- 
Thanks,
Oliver

WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oliver.upton@linux.dev>
To: Will Deacon <will@kernel.org>
Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH 2/2] KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support
Date: Wed, 1 May 2024 17:47:40 +0000	[thread overview]
Message-ID: <ZjKAPHJEy_WAtjsg@linux.dev> (raw)
In-Reply-To: <20240501163400.15838-3-will@kernel.org>

On Wed, May 01, 2024 at 05:34:00PM +0100, Will Deacon wrote:
> The early command line parsing treats "kvm-arm.mode=protected" as an
> alias for "id_aa64mmfr1.vh=0", forcing the use of nVHE so that the host
> kernel runs at EL1 with the pKVM hypervisor at EL2.
> 
> With the introduction of hVHE support in ad744e8cb346 ("arm64: Allow
> arm64_sw.hvhe on command line"), the hypervisor can run using the EL2+0
> translation regime. This is interesting for unusual CPUs that have VH
> stuck to 1, but also because it opens the possibility of a hypervisor
> "userspace" in the distant future which could be used to isolate vCPU
> contexts in the hypervisor (see Marc's talk from KVM Forum 2022 [1]).
> 
> Repaint the "kvm-arm.mode=protected" alias to map to "arm64_sw.hvhe=1",
> which will use hVHE on CPUs that support it and remain with nVHE
> otherwise.
> 
> [1] https://www.youtube.com/watch?v=1F_Mf2j9eIo
> Signed-off-by: Will Deacon <will@kernel.org>

Acked-by: Oliver Upton <oliver.upton@linux.dev>

-- 
Thanks,
Oliver

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  reply	other threads:[~2024-05-01 17:47 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-01 16:33 [PATCH 0/2] Tweaks to the kvm-arm.mode= early cmdline parsing Will Deacon
2024-05-01 16:33 ` Will Deacon
2024-05-01 16:33 ` [PATCH 1/2] KVM: arm64: Fix hvhe/nvhe early alias parsing Will Deacon
2024-05-01 16:33   ` Will Deacon
2024-05-01 17:44   ` Oliver Upton
2024-05-01 17:44     ` Oliver Upton
2024-05-02 10:20     ` Will Deacon
2024-05-02 10:20       ` Will Deacon
2024-05-06 17:35       ` Oliver Upton
2024-05-06 17:35         ` Oliver Upton
2024-05-01 16:34 ` [PATCH 2/2] KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support Will Deacon
2024-05-01 16:34   ` Will Deacon
2024-05-01 17:47   ` Oliver Upton [this message]
2024-05-01 17:47     ` Oliver Upton
2024-05-08  6:14 ` [PATCH 0/2] Tweaks to the kvm-arm.mode= early cmdline parsing Marc Zyngier
2024-05-08  6:14   ` Marc Zyngier

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