From: Jonathan Cameron <jonathan.cameron@huawei.com> To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, will.deacon@arm.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 1/8] iommu: Add I/O ASID allocator Date: Tue, 11 Jun 2019 10:36:25 +0100 Message-ID: <20190611103625.00001399@huawei.com> (raw) In-Reply-To: <20190610184714.6786-2-jean-philippe.brucker@arm.com> On Mon, 10 Jun 2019 19:47:07 +0100 Jean-Philippe Brucker <jean-philippe.brucker@arm.com> wrote: > Some devices might support multiple DMA address spaces, in particular > those that have the PCI PASID feature. PASID (Process Address Space ID) > allows to share process address spaces with devices (SVA), partition a > device into VM-assignable entities (VFIO mdev) or simply provide > multiple DMA address space to kernel drivers. Add a global PASID > allocator usable by different drivers at the same time. Name it I/O ASID > to avoid confusion with ASIDs allocated by arch code, which are usually > a separate ID space. > > The IOASID space is global. Each device can have its own PASID space, > but by convention the IOMMU ended up having a global PASID space, so > that with SVA, each mm_struct is associated to a single PASID. > > The allocator is primarily used by IOMMU subsystem but in rare occasions > drivers would like to allocate PASIDs for devices that aren't managed by > an IOMMU, using the same ID space as IOMMU. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Hi, A few trivial comments inline. May be more because I'm not that familiar with xa_array than anything else. Jonathan > --- > The most recent discussion on this patch was at: > https://lkml.kernel.org/lkml/1556922737-76313-4-git-send-email-jacob.jun.pan@linux.intel.com/ > I fixed it up a bit following comments in that series, and removed the > definitions for the custom allocator for now. > > There also is a new version that includes the custom allocator into this > patch, but is currently missing the RCU fixes, at: > https://lore.kernel.org/lkml/1560087862-57608-13-git-send-email-jacob.jun.pan@linux.intel.com/ > --- ... > + > +/** > + * ioasid_alloc - Allocate an IOASID > + * @set: the IOASID set > + * @min: the minimum ID (inclusive) > + * @max: the maximum ID (inclusive) > + * @private: data private to the caller > + * > + * Allocate an ID between @min and @max. The @private pointer is stored > + * internally and can be retrieved with ioasid_find(). > + * > + * Return: the allocated ID on success, or %INVALID_IOASID on failure. > + */ > +ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, > + void *private) > +{ > + u32 id = INVALID_IOASID; > + struct ioasid_data *data; > + > + data = kzalloc(sizeof(*data), GFP_KERNEL); > + if (!data) > + return INVALID_IOASID; > + > + data->set = set; > + data->private = private; > + > + if (xa_alloc(&ioasid_xa, &id, data, XA_LIMIT(min, max), GFP_KERNEL)) { > + pr_err("Failed to alloc ioasid from %d to %d\n", min, max); > + goto exit_free; > + } > + data->id = id; > + > +exit_free: This error flow is perhaps a little more confusing than it needs to be? My assumption (perhaps wrong) is that we only have an id == INVALID_IOASID if the xa_alloc fails, and that we will always have such an id value if it does (I'm not totally sure this second element is true in __xa_alloc). If I'm missing something perhaps a comment on how else we'd get here. > + if (id == INVALID_IOASID) { > + kfree(data); > + return INVALID_IOASID; > + } > + return id; > +} > +EXPORT_SYMBOL_GPL(ioasid_alloc); > + > +/** > + * ioasid_free - Free an IOASID > + * @ioasid: the ID to remove > + */ > +void ioasid_free(ioasid_t ioasid) > +{ > + struct ioasid_data *ioasid_data; > + > + ioasid_data = xa_erase(&ioasid_xa, ioasid); > + > + kfree_rcu(ioasid_data, rcu); > +} > +EXPORT_SYMBOL_GPL(ioasid_free); > + > +/** > + * ioasid_find - Find IOASID data > + * @set: the IOASID set > + * @ioasid: the IOASID to find > + * @getter: function to call on the found object > + * > + * The optional getter function allows to take a reference to the found object > + * under the rcu lock. The function can also check if the object is still valid: > + * if @getter returns false, then the object is invalid and NULL is returned. > + * > + * If the IOASID has been allocated for this set, return the private pointer > + * passed to ioasid_alloc. Private data can be NULL if not set. Return an error > + * if the IOASID is not found or does not belong to the set. Perhaps should make it clear that @set can be null. > + */ > +void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, > + bool (*getter)(void *)) > +{ > + void *priv = NULL; Set in all paths, so does need to be set here. > + struct ioasid_data *ioasid_data; > + > + rcu_read_lock(); > + ioasid_data = xa_load(&ioasid_xa, ioasid); > + if (!ioasid_data) { > + priv = ERR_PTR(-ENOENT); > + goto unlock; > + } > + if (set && ioasid_data->set != set) { > + /* data found but does not belong to the set */ > + priv = ERR_PTR(-EACCES); > + goto unlock; > + } > + /* Now IOASID and its set is verified, we can return the private data */ > + priv = rcu_dereference(ioasid_data->private); > + if (getter && !getter(priv)) > + priv = NULL; > +unlock: > + rcu_read_unlock(); > + > + return priv; > +} > +EXPORT_SYMBOL_GPL(ioasid_find); > + > +MODULE_LICENSE("GPL"); ... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply index Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-10 18:47 [PATCH 0/8] iommu: Add auxiliary domain and PASID support to Arm SMMUv3 Jean-Philippe Brucker 2019-06-10 18:47 ` [PATCH 1/8] iommu: Add I/O ASID allocator Jean-Philippe Brucker 2019-06-11 9:36 ` Jonathan Cameron [this message] 2019-06-11 14:35 ` Jean-Philippe Brucker 2019-06-11 18:13 ` Jacob Pan 2019-06-18 14:22 ` Jean-Philippe Brucker 2019-06-18 17:05 ` Jacob Pan 2019-06-19 14:26 ` Jean-Philippe Brucker 2019-06-11 12:26 ` Jacob Pan 2019-06-11 14:37 ` Jean-Philippe Brucker 2019-06-11 17:10 ` Jacob Pan 2019-06-12 11:30 ` Jean-Philippe Brucker 2019-06-10 18:47 ` [PATCH 2/8] dt-bindings: document PASID property for IOMMU masters Jean-Philippe Brucker 2019-07-08 7:58 ` Auger Eric 2019-06-10 18:47 ` [PATCH 3/8] iommu/arm-smmu-v3: Support platform SSID Jean-Philippe Brucker 2019-06-11 9:42 ` Jonathan Cameron 2019-06-11 14:35 ` Jean-Philippe Brucker 2019-06-18 18:08 ` Will Deacon 2019-06-19 11:53 ` Jean-Philippe Brucker 2019-07-08 7:58 ` Auger Eric 2019-09-19 14:51 ` Jean-Philippe Brucker 2019-06-10 18:47 ` [PATCH 4/8] iommu/arm-smmu-v3: Add support for Substream IDs Jean-Philippe Brucker 2019-06-11 10:19 ` Jonathan Cameron 2019-06-11 14:35 ` Jean-Philippe Brucker 2019-06-26 18:00 ` Will Deacon 2019-07-04 9:33 ` Jean-Philippe Brucker 2019-09-19 14:57 ` Jean-Philippe Brucker 2019-07-08 15:31 ` Auger Eric 2019-09-19 15:01 ` Jean-Philippe Brucker 2019-06-10 18:47 ` [PATCH 5/8] iommu/arm-smmu-v3: Add second level of context descriptor table Jean-Philippe Brucker 2019-06-11 10:24 ` Jonathan Cameron 2019-07-08 15:13 ` Auger Eric 2019-06-10 18:47 ` [PATCH 6/8] iommu/arm-smmu-v3: Support auxiliary domains Jean-Philippe Brucker 2019-06-26 17:59 ` Will Deacon 2019-07-05 16:29 ` Jean-Philippe Brucker 2019-09-19 15:06 ` Jean-Philippe Brucker 2019-06-10 18:47 ` [PATCH 7/8] iommu/arm-smmu-v3: Improve add_device() error handling Jean-Philippe Brucker 2019-07-08 7:58 ` Auger Eric 2019-06-10 18:47 ` [PATCH 8/8] iommu/arm-smmu-v3: Add support for PCI PASID Jean-Philippe Brucker 2019-06-11 10:45 ` Jonathan Cameron 2019-06-11 14:35 ` Jean-Philippe Brucker 2019-07-08 7:58 ` Auger Eric 2019-09-19 15:10 ` Jean-Philippe Brucker
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=20190611103625.00001399@huawei.com \ --to=jonathan.cameron@huawei.com \ --cc=devicetree@vger.kernel.org \ --cc=iommu@lists.linux-foundation.org \ --cc=jean-philippe.brucker@arm.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=mark.rutland@arm.com \ --cc=robh+dt@kernel.org \ --cc=robin.murphy@arm.com \ --cc=will.deacon@arm.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
Linux-ARM-Kernel Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/linux-arm-kernel/0 linux-arm-kernel/git/0.git git clone --mirror https://lore.kernel.org/linux-arm-kernel/1 linux-arm-kernel/git/1.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ https://lore.kernel.org/linux-arm-kernel \ linux-arm-kernel@lists.infradead.org public-inbox-index linux-arm-kernel Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.infradead.lists.linux-arm-kernel AGPL code for this site: git clone https://public-inbox.org/public-inbox.git