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From: Quentin Perret <qperret@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: kvm@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] KVM: arm64: Redefine pKVM memory transitions in terms of source/target
Date: Fri, 28 Oct 2022 09:57:04 +0000	[thread overview]
Message-ID: <Y1uncNq2oyc5wALG@google.com> (raw)
In-Reply-To: <20221028083448.1998389-3-oliver.upton@linux.dev>

Hey Oliver,

On Friday 28 Oct 2022 at 08:34:48 (+0000), Oliver Upton wrote:
> Perhaps it is just me, but the 'initiator' and 'completer' terms are
> slightly confusing descriptors for the addresses involved in a memory
> transition. Apply a rename to instead describe memory transitions in
> terms of a source and target address.

Just to provide some rationale for the initiator/completer terminology,
the very first implementation we did of this used 'sender/recipient (or
something along those lines I think), and we ended up confusing
ourselves massively. The main issue is that memory doesn't necessarily
'flow' in the same direction as the transition. It's all fine for a
donation or a share, but reclaim and unshare become funny. 'The
recipient of an unshare' can be easily misunderstood, I think.

So yeah, we ended up with initiator/completer, which may not be the
prettiest terminology, but it was useful to disambiguate things at
least.

Thanks for the review!
Quentin
_______________________________________________
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: Quentin Perret <qperret@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	kvmarm@lists.linux.dev, Will Deacon <will@kernel.org>,
	Fuad Tabba <tabba@google.com>,
	Vincent Donnefort <vdonnefort@google.com>
Subject: Re: [PATCH 2/2] KVM: arm64: Redefine pKVM memory transitions in terms of source/target
Date: Fri, 28 Oct 2022 09:57:04 +0000	[thread overview]
Message-ID: <Y1uncNq2oyc5wALG@google.com> (raw)
Message-ID: <20221028095704.kmFYUgdLEDJzgEqyIvrXEr5ICsCuSpRnRlsKsIjCRDE@z> (raw)
In-Reply-To: <20221028083448.1998389-3-oliver.upton@linux.dev>

Hey Oliver,

On Friday 28 Oct 2022 at 08:34:48 (+0000), Oliver Upton wrote:
> Perhaps it is just me, but the 'initiator' and 'completer' terms are
> slightly confusing descriptors for the addresses involved in a memory
> transition. Apply a rename to instead describe memory transitions in
> terms of a source and target address.

Just to provide some rationale for the initiator/completer terminology,
the very first implementation we did of this used 'sender/recipient (or
something along those lines I think), and we ended up confusing
ourselves massively. The main issue is that memory doesn't necessarily
'flow' in the same direction as the transition. It's all fine for a
donation or a share, but reclaim and unshare become funny. 'The
recipient of an unshare' can be easily misunderstood, I think.

So yeah, we ended up with initiator/completer, which may not be the
prettiest terminology, but it was useful to disambiguate things at
least.

Thanks for the review!
Quentin

WARNING: multiple messages have this Message-ID (diff)
From: Quentin Perret <qperret@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	kvmarm@lists.linux.dev, Will Deacon <will@kernel.org>,
	Fuad Tabba <tabba@google.com>,
	Vincent Donnefort <vdonnefort@google.com>
Subject: Re: [PATCH 2/2] KVM: arm64: Redefine pKVM memory transitions in terms of source/target
Date: Fri, 28 Oct 2022 09:57:04 +0000	[thread overview]
Message-ID: <Y1uncNq2oyc5wALG@google.com> (raw)
In-Reply-To: <20221028083448.1998389-3-oliver.upton@linux.dev>

Hey Oliver,

On Friday 28 Oct 2022 at 08:34:48 (+0000), Oliver Upton wrote:
> Perhaps it is just me, but the 'initiator' and 'completer' terms are
> slightly confusing descriptors for the addresses involved in a memory
> transition. Apply a rename to instead describe memory transitions in
> terms of a source and target address.

Just to provide some rationale for the initiator/completer terminology,
the very first implementation we did of this used 'sender/recipient (or
something along those lines I think), and we ended up confusing
ourselves massively. The main issue is that memory doesn't necessarily
'flow' in the same direction as the transition. It's all fine for a
donation or a share, but reclaim and unshare become funny. 'The
recipient of an unshare' can be easily misunderstood, I think.

So yeah, we ended up with initiator/completer, which may not be the
prettiest terminology, but it was useful to disambiguate things at
least.

Thanks for the review!
Quentin

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

  reply	other threads:[~2022-10-28  9:57 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-28  8:34 [PATCH 0/2] KVM: arm64: pKVM memory transitions cleanup Oliver Upton
2022-10-28  8:34 ` Oliver Upton
2022-10-28  8:34 ` Oliver Upton
2022-10-28  8:34 ` [PATCH 1/2] KVM: arm64: Clean out the odd handling of completer_addr Oliver Upton
2022-10-28  8:34   ` Oliver Upton
2022-10-28  8:34   ` Oliver Upton
2022-11-10 10:42   ` Will Deacon
2022-11-10 10:42     ` Will Deacon
2022-11-10 10:42     ` Will Deacon
2022-10-28  8:34 ` [PATCH 2/2] KVM: arm64: Redefine pKVM memory transitions in terms of source/target Oliver Upton
2022-10-28  8:34   ` Oliver Upton
2022-10-28  8:34   ` Oliver Upton
2022-10-28  9:57   ` Quentin Perret [this message]
2022-10-28  9:57     ` Quentin Perret
2022-10-28  9:57     ` Quentin Perret
2022-10-28 10:23     ` Oliver Upton
2022-10-28 10:23       ` Oliver Upton
2022-10-28 10:23       ` Oliver Upton
2022-11-10 10:46       ` Will Deacon
2022-11-10 10:46         ` Will Deacon
2022-11-10 10:46         ` Will Deacon

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