From: Oliver Upton <oliver.upton@linux.dev>
To: Ricardo Koller <ricarkol@google.com>
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] KVM: arm64: Don't serialize if the access flag isn't set
Date: Tue, 29 Nov 2022 21:15:21 +0000 [thread overview]
Message-ID: <Y4Z2aWVEnluy+d3+@google.com> (raw)
In-Reply-To: <Y4Zw/J3srTsZ57P7@google.com>
Hi Ricardo,
Thanks for having a look.
On Tue, Nov 29, 2022 at 12:52:12PM -0800, Ricardo Koller wrote:
> On Tue, Nov 29, 2022 at 07:19:44PM +0000, Oliver Upton wrote:
[...]
> > + ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
> > + &pte, NULL, 0);
> > + if (!ret)
> > + dsb(ishst);
>
> At the moment, the only reason for stage2_update_leaf_attrs() to not
> update the PTE is if it's not valid:
>
> if (!kvm_pte_valid(pte))
> return 0;
>
> I guess you could check that as well:
>
> + if (!ret || kvm_pte_valid(pte))
> + dsb(ishst);
Thanks for catching this.
Instead of pivoting on the returned PTE value, how about we return
-EAGAIN from the early return in stage2_attr_walker()? It would better
match the pattern used elsewhere in the pgtable code.
--
Thanks,
Oliver
next prev parent reply other threads:[~2022-11-29 21:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-29 19:19 [PATCH 0/4] KVM: arm64: Parallel access faults Oliver Upton
2022-11-29 19:19 ` [PATCH 1/4] KVM: arm64: Use KVM's pte type/helpers in handle_access_fault() Oliver Upton
2022-11-29 19:19 ` [PATCH 2/4] KVM: arm64: Don't serialize if the access flag isn't set Oliver Upton
2022-11-29 20:52 ` Ricardo Koller
2022-11-29 21:15 ` Oliver Upton [this message]
2022-11-30 1:23 ` Ricardo Koller
2022-11-30 8:21 ` Marc Zyngier
2022-11-30 23:21 ` Ricardo Koller
2022-12-01 18:11 ` Oliver Upton
2022-11-29 19:19 ` [PATCH 3/4] KVM: arm64: Handle access faults behind the read lock Oliver Upton
2022-11-29 21:00 ` Ricardo Koller
2022-11-29 19:19 ` [PATCH 4/4] KVM: arm64: Condition HW AF updates on config option Oliver Upton
2022-11-30 16:54 ` [PATCH 0/4] KVM: arm64: Parallel access faults Marc Zyngier
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