From: Jason Gunthorpe <jgg@ziepe.ca>
To: Baolu Lu <baolu.lu@linux.intel.com>
Cc: Tomasz Jeznach <tjeznach@rivosinc.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Anup Patel <apatel@ventanamicro.com>,
Sunil V L <sunilvl@ventanamicro.com>,
Nick Kossifidis <mick@ics.forth.gr>,
Sebastien Boeuf <seb@rivosinc.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
devicetree@vger.kernel.org, iommu@lists.linux.dev,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
linux@rivosinc.com
Subject: Re: [PATCH v2 7/7] iommu/riscv: Paging domain support
Date: Mon, 22 Apr 2024 16:30:59 -0300 [thread overview]
Message-ID: <20240422193059.GC231144@ziepe.ca> (raw)
In-Reply-To: <2f2750cd-a5bf-4486-8f50-c93d246f8b0c@linux.intel.com>
On Mon, Apr 22, 2024 at 01:21:05PM +0800, Baolu Lu wrote:
> > + /* Track domain to devices mapping. */
> > + if (bond)
> > + list_add_rcu(&bond->list, &domain->bonds);
> > +
> > + /* Remove tracking from previous domain, if needed. */
> > + iommu_domain = iommu_get_domain_for_dev(dev);
>
> Calling iommu_get_domain_for_dev() in the domain attaching path is very
> fragile because it heavily depends on the order of calling the attach
> callback and setting the domain pointer in the core.
We have a couple places doing this already, the core code accomodates
it well enough for deleting from a list.. So I think it is OK to keep
doing.
> Perhaps the driver can use dev_iommu_priv_set/get() to keep the active
> domain in the per-device private data?
>
> > + if (iommu_domain && !!(iommu_domain->type & __IOMMU_DOMAIN_PAGING)) {
> > + domain = iommu_domain_to_riscv(iommu_domain);
> > + bond = NULL;
> > + rcu_read_lock();
> > + list_for_each_entry_rcu(b, &domain->bonds, list) {
> > + if (b->dev == dev) {
> > + bond = b;
> > + break;
> > + }
> > + }
> > + rcu_read_unlock();
But now that I look again, this is not safe, you have to hold some
kind of per-domain lock to mutate the list. rcu_*read*_lock() cannot
be used for write.
Jason
next prev parent reply other threads:[~2024-04-22 19:31 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-18 16:32 [PATCH v2 0/7] Linux RISC-V IOMMU Support Tomasz Jeznach
2024-04-18 16:32 ` [PATCH v2 1/7] dt-bindings: iommu: riscv: Add bindings for RISC-V IOMMU Tomasz Jeznach
2024-04-18 17:04 ` Conor Dooley
2024-04-24 22:37 ` Tomasz Jeznach
2024-04-25 17:11 ` Conor Dooley
2024-04-22 14:04 ` Rob Herring
2024-04-18 16:32 ` [PATCH v2 2/7] iommu/riscv: Add RISC-V IOMMU platform device driver Tomasz Jeznach
2024-04-18 21:22 ` Robin Murphy
2024-04-24 21:59 ` Tomasz Jeznach
2024-04-25 11:23 ` Robin Murphy
2024-04-18 16:32 ` [PATCH v2 3/7] iommu/riscv: Add RISC-V IOMMU PCIe " Tomasz Jeznach
2024-04-18 22:07 ` Robin Murphy
2024-04-18 16:32 ` [PATCH v2 4/7] iommu/riscv: Enable IOMMU registration and device probe Tomasz Jeznach
2024-04-18 16:32 ` [PATCH v2 5/7] iommu/riscv: Device directory management Tomasz Jeznach
2024-04-19 12:40 ` Jason Gunthorpe
2024-04-24 23:01 ` Tomasz Jeznach
2024-04-24 23:07 ` Jason Gunthorpe
2024-04-22 5:11 ` Baolu Lu
2024-04-24 23:07 ` Tomasz Jeznach
2024-04-18 16:32 ` [PATCH v2 6/7] iommu/riscv: Command and fault queue support Tomasz Jeznach
2024-04-18 16:32 ` [PATCH v2 7/7] iommu/riscv: Paging domain support Tomasz Jeznach
2024-04-19 12:56 ` Jason Gunthorpe
2024-04-22 7:40 ` Baolu Lu
2024-04-24 23:30 ` Tomasz Jeznach
2024-04-24 23:39 ` Jason Gunthorpe
2024-04-24 23:54 ` Tomasz Jeznach
2024-04-25 0:48 ` Jason Gunthorpe
2024-04-22 5:21 ` Baolu Lu
2024-04-22 19:30 ` Jason Gunthorpe [this message]
2024-04-23 17:00 ` Andrew Jones
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