From: Andrew Scull <ascull@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
dave.martin@arm.com, daniel.kiss@arm.com,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
broonie@kernel.org, kernel-team@android.com
Subject: Re: [PATCH 08/10] KVM: arm64: Add a nVHE-specific SVE VQ reset hypercall
Date: Tue, 16 Mar 2021 14:24:38 +0000 [thread overview]
Message-ID: <YFC/pmzqSuXq+3+I@google.com> (raw)
In-Reply-To: <20210316101312.102925-9-maz@kernel.org>
On Tue, Mar 16, 2021 at 10:13:10AM +0000, Marc Zyngier wrote:
> ZCR_EL2 controls the upper bound for ZCR_EL1, and is set to
> a potentially lower limit when the guest uses SVE.
>
> In order to restore the SVE state on the EL1 host, we must first
> reset ZCR_EL2 to its original value.
>
> Provide a hypervall that perform this reset.
Is there a good reason to have an explicit hypercall vs trapping the
host access to SVE and restoring in that event?
It's quite easy to do trap handling at EL2 now and it could let things
be even lazier, if that's any benefit in this case.
Trapping seems to have had a bad rep in other conversations but I'm not
sure the same reasoning applies to this as well, or not.
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Scull <ascull@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kernel-team@android.com, kvm@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
kvmarm@lists.cs.columbia.edu, broonie@kernel.org,
Will Deacon <will@kernel.org>,
dave.martin@arm.com, linux-arm-kernel@lists.infradead.org,
daniel.kiss@arm.com
Subject: Re: [PATCH 08/10] KVM: arm64: Add a nVHE-specific SVE VQ reset hypercall
Date: Tue, 16 Mar 2021 14:24:38 +0000 [thread overview]
Message-ID: <YFC/pmzqSuXq+3+I@google.com> (raw)
In-Reply-To: <20210316101312.102925-9-maz@kernel.org>
On Tue, Mar 16, 2021 at 10:13:10AM +0000, Marc Zyngier wrote:
> ZCR_EL2 controls the upper bound for ZCR_EL1, and is set to
> a potentially lower limit when the guest uses SVE.
>
> In order to restore the SVE state on the EL1 host, we must first
> reset ZCR_EL2 to its original value.
>
> Provide a hypervall that perform this reset.
Is there a good reason to have an explicit hypercall vs trapping the
host access to SVE and restoring in that event?
It's quite easy to do trap handling at EL2 now and it could let things
be even lazier, if that's any benefit in this case.
Trapping seems to have had a bad rep in other conversations but I'm not
sure the same reasoning applies to this as well, or not.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Scull <ascull@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
dave.martin@arm.com, daniel.kiss@arm.com,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
broonie@kernel.org, kernel-team@android.com
Subject: Re: [PATCH 08/10] KVM: arm64: Add a nVHE-specific SVE VQ reset hypercall
Date: Tue, 16 Mar 2021 14:24:38 +0000 [thread overview]
Message-ID: <YFC/pmzqSuXq+3+I@google.com> (raw)
In-Reply-To: <20210316101312.102925-9-maz@kernel.org>
On Tue, Mar 16, 2021 at 10:13:10AM +0000, Marc Zyngier wrote:
> ZCR_EL2 controls the upper bound for ZCR_EL1, and is set to
> a potentially lower limit when the guest uses SVE.
>
> In order to restore the SVE state on the EL1 host, we must first
> reset ZCR_EL2 to its original value.
>
> Provide a hypervall that perform this reset.
Is there a good reason to have an explicit hypercall vs trapping the
host access to SVE and restoring in that event?
It's quite easy to do trap handling at EL2 now and it could let things
be even lazier, if that's any benefit in this case.
Trapping seems to have had a bad rep in other conversations but I'm not
sure the same reasoning applies to this as well, or not.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-16 14:25 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 10:13 [PATCH 00/10] KVM: arm64: Enable SVE support on nVHE systems Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` [PATCH 01/10] KVM: arm64: Provide KVM's own save/restore SVE primitives Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:31 ` Quentin Perret
2021-03-16 10:31 ` Quentin Perret
2021-03-16 10:31 ` Quentin Perret
2021-03-16 12:17 ` Marc Zyngier
2021-03-16 12:17 ` Marc Zyngier
2021-03-16 12:17 ` Marc Zyngier
2021-03-17 14:30 ` Will Deacon
2021-03-17 14:30 ` Will Deacon
2021-03-17 14:30 ` Will Deacon
2021-03-16 10:13 ` [PATCH 02/10] KVM: arm64: Use {read,write}_sysreg_el1 to access ZCR_EL1 Marc Zyngier
2021-03-16 10:13 ` [PATCH 02/10] KVM: arm64: Use {read, write}_sysreg_el1 " Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 14:31 ` [PATCH 02/10] KVM: arm64: Use {read,write}_sysreg_el1 " Will Deacon
2021-03-17 14:31 ` Will Deacon
2021-03-17 14:31 ` Will Deacon
2021-03-16 10:13 ` [PATCH 03/10] KVM: arm64: Let vcpu_sve_pffr() handle HYP VAs Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 14:31 ` Will Deacon
2021-03-17 14:31 ` Will Deacon
2021-03-17 14:31 ` Will Deacon
2021-03-16 10:13 ` [PATCH 04/10] KVM: arm64: Introduce vcpu_sve_vq() helper Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 14:01 ` Will Deacon
2021-03-17 14:01 ` Will Deacon
2021-03-17 14:01 ` Will Deacon
2021-03-16 10:13 ` [PATCH 05/10] KVM: arm64: Rework SVE host-save/guest-restore Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 14:29 ` Will Deacon
2021-03-17 14:29 ` Will Deacon
2021-03-17 14:29 ` Will Deacon
2021-03-17 14:54 ` Marc Zyngier
2021-03-17 14:54 ` Marc Zyngier
2021-03-17 14:54 ` Marc Zyngier
2021-03-16 10:13 ` [PATCH 06/10] KVM: arm64: Map SVE context at EL2 when available Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 16:01 ` Will Deacon
2021-03-17 16:01 ` Will Deacon
2021-03-17 16:01 ` Will Deacon
2021-03-18 8:56 ` Marc Zyngier
2021-03-18 8:56 ` Marc Zyngier
2021-03-18 8:56 ` Marc Zyngier
2021-03-16 10:13 ` [PATCH 07/10] KVM: arm64: Save guest's ZCR_EL1 before saving the FPSIMD state Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 17:17 ` Will Deacon
2021-03-17 17:17 ` Will Deacon
2021-03-17 17:17 ` Will Deacon
2021-03-17 17:20 ` Will Deacon
2021-03-17 17:20 ` Will Deacon
2021-03-17 17:20 ` Will Deacon
2021-03-16 10:13 ` [PATCH 08/10] KVM: arm64: Add a nVHE-specific SVE VQ reset hypercall Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:45 ` Quentin Perret
2021-03-16 10:45 ` Quentin Perret
2021-03-16 10:45 ` Quentin Perret
2021-03-16 12:18 ` Marc Zyngier
2021-03-16 12:18 ` Marc Zyngier
2021-03-16 12:18 ` Marc Zyngier
2021-03-16 14:24 ` Andrew Scull [this message]
2021-03-16 14:24 ` Andrew Scull
2021-03-16 14:24 ` Andrew Scull
2021-03-16 15:00 ` Marc Zyngier
2021-03-16 15:00 ` Marc Zyngier
2021-03-16 15:00 ` Marc Zyngier
2021-03-16 10:13 ` [PATCH 09/10] KVM: arm64: Save/restore SVE state for nVHE Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 17:57 ` Will Deacon
2021-03-17 17:57 ` Will Deacon
2021-03-17 17:57 ` Will Deacon
2021-03-18 9:12 ` Marc Zyngier
2021-03-18 9:12 ` Marc Zyngier
2021-03-18 9:12 ` Marc Zyngier
2021-03-16 10:13 ` [PATCH 10/10] KVM: arm64: Enable SVE support " Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-16 10:13 ` Marc Zyngier
2021-03-17 18:00 ` Will Deacon
2021-03-17 18:00 ` Will Deacon
2021-03-17 18:00 ` Will Deacon
2021-03-18 9:14 ` Marc Zyngier
2021-03-18 9:14 ` Marc Zyngier
2021-03-18 9:14 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YFC/pmzqSuXq+3+I@google.com \
--to=ascull@google.com \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=daniel.kiss@arm.com \
--cc=dave.martin@arm.com \
--cc=james.morse@arm.com \
--cc=julien.thierry.kdev@gmail.com \
--cc=kernel-team@android.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=maz@kernel.org \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.