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From: Ricardo Koller <ricarkol@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Ben Gardon <bgardon@google.com>,
	pbonzini@redhat.com, maz@kernel.org, yuzenghui@huawei.com,
	dmatlack@google.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev,
	qperret@google.com, catalin.marinas@arm.com,
	andrew.jones@linux.dev, seanjc@google.com,
	alexandru.elisei@arm.com, suzuki.poulose@arm.com,
	eric.auger@redhat.com, gshan@redhat.com, reijiw@google.com,
	rananta@google.com, ricarkol@gmail.com
Subject: Re: [PATCH 1/9] KVM: arm64: Add KVM_PGTABLE_WALK_REMOVED into ctx->flags
Date: Tue, 24 Jan 2023 08:32:50 -0800	[thread overview]
Message-ID: <Y9AIMtJEgEjoVWQA@google.com> (raw)
In-Reply-To: <Y88sq1cQUzVj9B4D@google.com>

On Tue, Jan 24, 2023 at 12:56:11AM +0000, Oliver Upton wrote:
> On Mon, Jan 23, 2023 at 04:51:16PM -0800, Ben Gardon wrote:
> > On Thu, Jan 12, 2023 at 7:50 PM Ricardo Koller <ricarkol@google.com> wrote:
> > >
> > > Add a flag to kvm_pgtable_visit_ctx, KVM_PGTABLE_WALK_REMOVED, to
> > > indicate that the walk is on a removed table not accesible to the HW
> > > page-table walker. Then use it to avoid doing break-before-make or
> > > performing CMOs (Cache Maintenance Operations) when mapping a removed
> > 
> > Nit: Should this say unmapping? Or are we actually going to use this
> > to map memory ?
> 
> I think the *_REMOVED term feels weird as it relates to constructing a
> page table. It'd be better if we instead added flags to describe the
> operations we intend to elide (i.e. CMOs and TLBIs).

What about KVM_PGTABLE_WALK_ELIDE_BBM and KVM_PGTABLE_WALK_ELIDE_CMO?

> That way the
> implementation is generic enough that we can repurpose it for other use
> cases.

Aha, good point. I actually have a use case for it (FEAT_BBM).

> 
> --
> Thanks,
> Oliver

  reply	other threads:[~2023-01-24 16:32 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-13  3:49 [PATCH 0/9] KVM: arm64: Eager Huge-page splitting for dirty-logging Ricardo Koller
2023-01-13  3:49 ` [PATCH 1/9] KVM: arm64: Add KVM_PGTABLE_WALK_REMOVED into ctx->flags Ricardo Koller
2023-01-24  0:51   ` Ben Gardon
2023-01-24  0:56     ` Oliver Upton
2023-01-24 16:32       ` Ricardo Koller [this message]
2023-01-24 18:00         ` Ben Gardon
2023-01-26 18:48           ` Ricardo Koller
2023-01-24 16:30     ` Ricardo Koller
2023-01-13  3:49 ` [PATCH 2/9] KVM: arm64: Add helper for creating removed stage2 subtrees Ricardo Koller
2023-01-14 17:58   ` kernel test robot
2023-01-24  0:55   ` Ben Gardon
2023-01-24 16:35     ` Ricardo Koller
2023-01-24 17:07       ` Oliver Upton
2023-01-13  3:49 ` [PATCH 3/9] KVM: arm64: Add kvm_pgtable_stage2_split() Ricardo Koller
2023-01-24  1:03   ` Ben Gardon
2023-01-24 16:46     ` Ricardo Koller
2023-01-24 17:11       ` Oliver Upton
2023-01-24 17:18         ` Ricardo Koller
2023-01-24 17:48           ` David Matlack
2023-01-24 20:28             ` Oliver Upton
2023-02-06  9:20   ` Zheng Chuan
2023-02-06 16:28     ` Ricardo Koller
2023-01-13  3:49 ` [PATCH 4/9] KVM: arm64: Refactor kvm_arch_commit_memory_region() Ricardo Koller
2023-01-13  3:49 ` [PATCH 5/9] KVM: arm64: Add kvm_uninit_stage2_mmu() Ricardo Koller
2023-01-13  3:49 ` [PATCH 6/9] KVM: arm64: Split huge pages when dirty logging is enabled Ricardo Koller
2023-01-24 17:52   ` Ben Gardon
2023-01-24 22:19     ` Oliver Upton
2023-01-24 22:45   ` Oliver Upton
2023-01-26 18:45     ` Ricardo Koller
2023-01-26 19:25       ` Ricardo Koller
2023-01-26 20:10       ` Marc Zyngier
2023-01-27 15:45         ` Ricardo Koller
2023-01-30 21:18           ` Oliver Upton
2023-01-31  1:18             ` Sean Christopherson
2023-01-31 17:45               ` Oliver Upton
2023-01-31 17:54                 ` Sean Christopherson
2023-01-31 19:06                   ` Oliver Upton
2023-01-31 18:01                 ` David Matlack
2023-01-31 18:19                   ` Ricardo Koller
2023-01-31 18:35                   ` Oliver Upton
2023-01-31 10:31             ` Marc Zyngier
2023-01-31 10:28           ` Marc Zyngier
2023-02-06 16:35             ` Ricardo Koller
2023-01-13  3:49 ` [PATCH 7/9] KVM: arm64: Open-code kvm_mmu_write_protect_pt_masked() Ricardo Koller
2023-01-13  3:49 ` [PATCH 8/9] KVM: arm64: Split huge pages during KVM_CLEAR_DIRTY_LOG Ricardo Koller
2023-01-13  3:50 ` [PATCH 9/9] KVM: arm64: Use local TLBI on permission relaxation Ricardo Koller
2023-01-24  0:48 ` [PATCH 0/9] KVM: arm64: Eager Huge-page splitting for dirty-logging Ben Gardon
2023-01-24 16:50   ` Ricardo Koller

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