From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev,
Ben Gardon <bgardon@google.com>,
David Matlack <dmatlack@google.com>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 00/15] KVM: arm64: Parallel stage-2 fault handling
Date: Thu, 27 Oct 2022 23:39:11 +0000 [thread overview]
Message-ID: <Y1sWnyHvMWP/DhHm@google.com> (raw)
In-Reply-To: <20221027221752.1683510-1-oliver.upton@linux.dev>
On Thu, Oct 27, 2022 at 10:17:37PM +0000, Oliver Upton wrote:
> Presently KVM only takes a read lock for stage 2 faults if it believes
> the fault can be fixed by relaxing permissions on a PTE (write unprotect
> for dirty logging). Otherwise, stage 2 faults grab the write lock, which
> predictably can pile up all the vCPUs in a sufficiently large VM.
>
> Like the TDP MMU for x86, this series loosens the locking around
> manipulations of the stage 2 page tables to allow parallel faults. RCU
> and atomics are exploited to safely build/destroy the stage 2 page
> tables in light of multiple software observers.
>
> Patches 1-4 clean up the context associated with a page table walk / PTE
> visit. This is helpful for:
> - Extending the context passed through for a visit
> - Building page table walkers that operate outside of a kvm_pgtable
> context (e.g. RCU callback)
As is always the case, I failed to update the changelogs when twiddling
things around a bit more.
Specifically, 8/15 and 14/15 don't directly match the diffs anymore. I
wont respin (yet) to avoid bombarding mailboxes.
--
Thanks,
Oliver
_______________________________________________
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: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Reiji Watanabe <reijiw@google.com>,
Ricardo Koller <ricarkol@google.com>,
David Matlack <dmatlack@google.com>,
Quentin Perret <qperret@google.com>,
Ben Gardon <bgardon@google.com>, Gavin Shan <gshan@redhat.com>,
Peter Xu <peterx@redhat.com>, Will Deacon <will@kernel.org>,
Sean Christopherson <seanjc@google.com>,
kvmarm@lists.linux.dev
Subject: Re: [PATCH v3 00/15] KVM: arm64: Parallel stage-2 fault handling
Date: Thu, 27 Oct 2022 23:39:11 +0000 [thread overview]
Message-ID: <Y1sWnyHvMWP/DhHm@google.com> (raw)
Message-ID: <20221027233911.5uiUhreWmHqIJQq0QYiVyCs3gOztPMV0dTZL1Xc1oZM@z> (raw)
In-Reply-To: <20221027221752.1683510-1-oliver.upton@linux.dev>
On Thu, Oct 27, 2022 at 10:17:37PM +0000, Oliver Upton wrote:
> Presently KVM only takes a read lock for stage 2 faults if it believes
> the fault can be fixed by relaxing permissions on a PTE (write unprotect
> for dirty logging). Otherwise, stage 2 faults grab the write lock, which
> predictably can pile up all the vCPUs in a sufficiently large VM.
>
> Like the TDP MMU for x86, this series loosens the locking around
> manipulations of the stage 2 page tables to allow parallel faults. RCU
> and atomics are exploited to safely build/destroy the stage 2 page
> tables in light of multiple software observers.
>
> Patches 1-4 clean up the context associated with a page table walk / PTE
> visit. This is helpful for:
> - Extending the context passed through for a visit
> - Building page table walkers that operate outside of a kvm_pgtable
> context (e.g. RCU callback)
As is always the case, I failed to update the changelogs when twiddling
things around a bit more.
Specifically, 8/15 and 14/15 don't directly match the diffs anymore. I
wont respin (yet) to avoid bombarding mailboxes.
--
Thanks,
Oliver
WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Reiji Watanabe <reijiw@google.com>,
Ricardo Koller <ricarkol@google.com>,
David Matlack <dmatlack@google.com>,
Quentin Perret <qperret@google.com>,
Ben Gardon <bgardon@google.com>, Gavin Shan <gshan@redhat.com>,
Peter Xu <peterx@redhat.com>, Will Deacon <will@kernel.org>,
Sean Christopherson <seanjc@google.com>,
kvmarm@lists.linux.dev
Subject: Re: [PATCH v3 00/15] KVM: arm64: Parallel stage-2 fault handling
Date: Thu, 27 Oct 2022 23:39:11 +0000 [thread overview]
Message-ID: <Y1sWnyHvMWP/DhHm@google.com> (raw)
In-Reply-To: <20221027221752.1683510-1-oliver.upton@linux.dev>
On Thu, Oct 27, 2022 at 10:17:37PM +0000, Oliver Upton wrote:
> Presently KVM only takes a read lock for stage 2 faults if it believes
> the fault can be fixed by relaxing permissions on a PTE (write unprotect
> for dirty logging). Otherwise, stage 2 faults grab the write lock, which
> predictably can pile up all the vCPUs in a sufficiently large VM.
>
> Like the TDP MMU for x86, this series loosens the locking around
> manipulations of the stage 2 page tables to allow parallel faults. RCU
> and atomics are exploited to safely build/destroy the stage 2 page
> tables in light of multiple software observers.
>
> Patches 1-4 clean up the context associated with a page table walk / PTE
> visit. This is helpful for:
> - Extending the context passed through for a visit
> - Building page table walkers that operate outside of a kvm_pgtable
> context (e.g. RCU callback)
As is always the case, I failed to update the changelogs when twiddling
things around a bit more.
Specifically, 8/15 and 14/15 don't directly match the diffs anymore. I
wont respin (yet) to avoid bombarding mailboxes.
--
Thanks,
Oliver
_______________________________________________
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:[~2022-10-27 23:39 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-27 22:17 [PATCH v3 00/15] KVM: arm64: Parallel stage-2 fault handling Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 01/15] KVM: arm64: Combine visitor arguments into a context structure Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 02/15] KVM: arm64: Stash observed pte value in visitor context Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 03/15] KVM: arm64: Pass mm_ops through the " Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 04/15] KVM: arm64: Don't pass kvm_pgtable through kvm_pgtable_walk_data Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 05/15] KVM: arm64: Add a helper to tear down unlinked stage-2 subtrees Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 06/15] KVM: arm64: Tear down unlinked stage-2 subtree after break-before-make Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 07/15] KVM: arm64: Use an opaque type for pteps Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` [PATCH v3 08/15] KVM: arm64: Protect stage-2 traversal with RCU Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-28 7:36 ` kernel test robot
2022-10-28 7:36 ` kernel test robot
2022-10-28 9:19 ` Oliver Upton
2022-10-28 9:19 ` Oliver Upton
2022-10-28 9:19 ` Oliver Upton
2022-11-01 20:22 ` Sean Christopherson
2022-11-01 20:22 ` Sean Christopherson
2022-11-01 20:22 ` Sean Christopherson
2022-10-27 22:17 ` [PATCH v3 09/15] KVM: arm64: Free removed stage-2 tables in RCU callback Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-10-27 22:17 ` Oliver Upton
2022-11-01 20:28 ` Sean Christopherson
2022-11-01 20:28 ` Sean Christopherson
2022-11-01 20:28 ` Sean Christopherson
2022-11-01 20:46 ` Oliver Upton
2022-11-01 20:46 ` Oliver Upton
2022-11-01 20:46 ` Oliver Upton
2022-11-01 21:07 ` Sean Christopherson
2022-11-01 21:07 ` Sean Christopherson
2022-11-01 21:07 ` Sean Christopherson
2022-10-27 22:22 ` [PATCH v3 10/15] KVM: arm64: Atomically update stage 2 leaf attributes in parallel walks Oliver Upton
2022-10-27 22:22 ` Oliver Upton
2022-10-27 22:22 ` Oliver Upton
2022-10-28 10:18 ` kernel test robot
2022-10-28 10:18 ` kernel test robot
2022-10-27 22:22 ` [PATCH v3 11/15] KVM: arm64: Split init and set for table PTE Oliver Upton
2022-10-27 22:22 ` Oliver Upton
2022-10-27 22:22 ` Oliver Upton
2022-10-27 22:22 ` [PATCH v3 12/15] KVM: arm64: Make block->table PTE changes parallel-aware Oliver Upton
2022-10-27 22:22 ` Oliver Upton
2022-10-27 22:22 ` Oliver Upton
2022-11-02 2:22 ` Ricardo Koller
2022-11-02 2:22 ` Ricardo Koller
2022-11-02 2:22 ` Ricardo Koller
2022-11-02 23:03 ` Oliver Upton
2022-11-02 23:03 ` Oliver Upton
2022-11-02 23:03 ` Oliver Upton
2022-10-27 22:23 ` [PATCH v3 13/15] KVM: arm64: Make leaf->leaf " Oliver Upton
2022-10-27 22:23 ` Oliver Upton
2022-10-27 22:23 ` Oliver Upton
2022-10-27 22:23 ` [PATCH v3 14/15] KVM: arm64: Make table->block " Oliver Upton
2022-10-27 22:23 ` Oliver Upton
2022-10-27 22:23 ` Oliver Upton
2022-10-27 22:23 ` [PATCH v3 15/15] KVM: arm64: Handle stage-2 faults in parallel Oliver Upton
2022-10-27 22:23 ` Oliver Upton
2022-10-27 22:23 ` Oliver Upton
2022-10-27 23:39 ` Oliver Upton [this message]
2022-10-27 23:39 ` [PATCH v3 00/15] KVM: arm64: Parallel stage-2 fault handling Oliver Upton
2022-10-27 23:39 ` Oliver Upton
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