From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
will@kernel.org, catalin.marinas@arm.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, robin.murphy@arm.com,
nicolinc@nvidia.com, linux-arm-kernel@lists.infradead.org,
kvm@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>,
zhi.wang.linux@gmail.com, Sean Christopherson <seanjc@google.com>
Subject: Re: [PATCH 2/2] arm64: Notify on pte permission upgrades
Date: Tue, 30 May 2023 08:54:39 -0300 [thread overview]
Message-ID: <ZHXj/6Bjraxqk4YR@nvidia.com> (raw)
In-Reply-To: <87pm6ii6qi.fsf@nvidia.com>
On Tue, May 30, 2023 at 06:05:41PM +1000, Alistair Popple wrote:
>
> >> As no notification is sent and the SMMU does not snoop TLB invalidates
> >> it will continue to return read-only entries to a device even though
> >> the CPU page table contains a writable entry. This leads to a
> >> continually faulting device and no way of handling the fault.
> >
> > Doesn't the fault generate a PRI/etc? If we get a PRI maybe we should
> > just have the iommu driver push an iotlb invalidation command before
> > it acks it? PRI is already really slow so I'm not sure a pipelined
> > invalidation is going to be a problem? Does the SMMU architecture
> > permit negative caching which would suggest we need it anyhow?
>
> Yes, SMMU architecture (which matches the ARM architecture in regards to
> TLB maintenance requirements) permits negative caching of some mapping
> attributes including the read-only attribute. Hence without the flushing
> we fault continuously.
Sounds like a straight up SMMU bug, invalidate the cache after
resolving the PRI event.
Jason
next prev parent reply other threads:[~2023-05-30 11:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-24 1:47 [PATCH 1/2] mmu_notifiers: Restore documentation for .invalidate_range() Alistair Popple
2023-05-24 1:47 ` [PATCH 2/2] arm64: Notify on pte permission upgrades Alistair Popple
2023-05-28 0:02 ` Jason Gunthorpe
2023-05-30 8:05 ` Alistair Popple
2023-05-30 11:54 ` Jason Gunthorpe [this message]
2023-05-30 12:14 ` Robin Murphy
2023-05-30 12:52 ` Jason Gunthorpe
2023-05-30 13:44 ` Robin Murphy
2023-05-30 14:06 ` Jason Gunthorpe
2023-05-30 21:44 ` Sean Christopherson
2023-05-30 23:08 ` Jason Gunthorpe
2023-05-31 0:30 ` Alistair Popple
2023-05-31 0:32 ` Jason Gunthorpe
2023-05-31 2:46 ` Alistair Popple
2023-05-31 15:30 ` Jason Gunthorpe
[not found] ` <31cdd164783fefad4c9ef4a6d33c1e0094405d0f03added523a82dd9febdf15f@mu.id>
2023-06-09 2:06 ` Alistair Popple
2023-06-09 6:05 ` Alistair Popple
2023-05-24 2:20 ` [PATCH 1/2] mmu_notifiers: Restore documentation for .invalidate_range() John Hubbard
2023-05-24 4:45 ` Alistair Popple
2023-05-24 3:48 ` Zhi Wang
2023-05-24 4:57 ` Alistair Popple
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=ZHXj/6Bjraxqk4YR@nvidia.com \
--to=jgg@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=apopple@nvidia.com \
--cc=catalin.marinas@arm.com \
--cc=jhubbard@nvidia.com \
--cc=kvm@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=nicolinc@nvidia.com \
--cc=robin.murphy@arm.com \
--cc=seanjc@google.com \
--cc=will@kernel.org \
--cc=zhi.wang.linux@gmail.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox