Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752087AbdFSRTP (ORCPT ); Mon, 19 Jun 2017 13:19:15 -0400 Received: from foss.arm.com ([217.140.101.70]:54968 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751083AbdFSRTN (ORCPT ); Mon, 19 Jun 2017 13:19:13 -0400 Subject: Re: [PATCH v4 02/09] iommu/ipmmu-vmsa: Add optional root device feature To: Magnus Damm , joro@8bytes.org Cc: laurent.pinchart+renesas@ideasonboard.com, geert+renesas@glider.be, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, iommu@lists.linux-foundation.org, horms+renesas@verge.net.au, m.szyprowski@samsung.com References: <149786362527.14868.2143461703972595839.sendpatchset@little-apple> <149786364660.14868.13384595731879361399.sendpatchset@little-apple> From: Robin Murphy Message-ID: <8ba73c68-1e82-e7d3-3764-398fa4f2f706@arm.com> Date: Mon, 19 Jun 2017 18:19:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <149786364660.14868.13384595731879361399.sendpatchset@little-apple> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8612 Lines: 269 On 19/06/17 10:14, Magnus Damm wrote: > From: Magnus Damm > > Add root device handling to the IPMMU driver by allowing certain > DT compat strings to enable has_cache_leaf_nodes that in turn will > support both root devices with interrupts and leaf devices that > face the actual IPMMU consumer devices. > > Signed-off-by: Magnus Damm > --- > > Changes since V3: > - Reworked root finding code to make it easier to follow, thanks Geert! > > Changes since V2: > - Fixed a bug in ipmmu_find_root() when only leaf devices are present > - Broke out __ipmmu_find_root() to allow ->xlate() check for root devices > > Changes since V1: > - Moved patch to earlier in the series > - Updated code to work with recent changes in: > [PATCH v3 00/06] iommu/ipmmu-vmsa: IPMMU multi-arch update V3 > > drivers/iommu/ipmmu-vmsa.c | 95 ++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 78 insertions(+), 17 deletions(-) > > --- 0015/drivers/iommu/ipmmu-vmsa.c > +++ work/drivers/iommu/ipmmu-vmsa.c 2017-06-19 13:59:41.050607110 +0900 > @@ -36,6 +36,7 @@ > > struct ipmmu_features { > bool use_ns_alias_offset; > + bool has_cache_leaf_nodes; > }; > > struct ipmmu_vmsa_device { > @@ -44,6 +45,7 @@ struct ipmmu_vmsa_device { > struct iommu_device iommu; > struct list_head list; > const struct ipmmu_features *features; > + bool is_leaf; > unsigned int num_utlbs; > spinlock_t lock; /* Protects ctx and domains[] */ > DECLARE_BITMAP(ctx, IPMMU_CTX_MAX); > @@ -54,6 +56,7 @@ struct ipmmu_vmsa_device { > > struct ipmmu_vmsa_domain { > struct ipmmu_vmsa_device *mmu; > + struct ipmmu_vmsa_device *root; Would it not make more sense for this to be a property of the ipmmu_device itself, rather than per ipmmu_domain? I may of course have got the wrong idea of the topology here, but it seems as if mmu->is_leaf could be expressed as mmu->root == mmu vs. mmu->root == some_other_mmu, at which point there's one less thing to worry about in the domain. > struct iommu_domain io_domain; > > struct io_pgtable_cfg cfg; > @@ -203,6 +206,44 @@ static struct ipmmu_vmsa_iommu_priv *to_ > #define IMUASID_ASID0_SHIFT 0 > > /* ----------------------------------------------------------------------------- > + * Root device handling > + */ > + > +static bool ipmmu_is_root(struct ipmmu_vmsa_device *mmu) > +{ > + if (mmu->features->has_cache_leaf_nodes) > + return mmu->is_leaf ? false : true> + else > + return true; /* older IPMMU hardware treated as single root */ > +} > + > +static struct ipmmu_vmsa_device *__ipmmu_find_root(void) > +{ > + struct ipmmu_vmsa_device *mmu; > + struct ipmmu_vmsa_device *root = NULL; > + > + spin_lock(&ipmmu_devices_lock); > + > + list_for_each_entry(mmu, &ipmmu_devices, list) { > + if (ipmmu_is_root(mmu)) { > + root = mmu; > + break; > + } > + } > + > + spin_unlock(&ipmmu_devices_lock); > + return root; > +} I wonder if it might be tidier to use driver_for_each_device() for this, and remove the local list at the same time as its previous user. Either way, what happens if things end up hapening in this order: 1: probe leaf IPMMU B 2: probe device X behind IPMMU B 3: create and attach default domain for device X 4: probe root IPMMU A We know X will defer if B isn't ready, but it doesn't seem (at a glance, admittedly) that there's anything to enforce the expected probe ordering between A and B. This seems like another argument for moving the root/leaf association up to the device level, such that B can look up A once in its own probe routine, and defer itself if necessary. > + > +static struct ipmmu_vmsa_device *ipmmu_find_root(struct ipmmu_vmsa_device *leaf) > +{ > + if (ipmmu_is_root(leaf)) > + return leaf; > + else > + return __ipmmu_find_root(); Well actually, looking at that, I think what we have here is a very long-winded way of implementing this: static ipmmu_vmsa_device *root; Yuck. > +} > + > +/* ----------------------------------------------------------------------------- > * Read/Write Access > */ > > @@ -219,13 +260,13 @@ static void ipmmu_write(struct ipmmu_vms > > static u32 ipmmu_ctx_read(struct ipmmu_vmsa_domain *domain, unsigned int reg) > { > - return ipmmu_read(domain->mmu, domain->context_id * IM_CTX_SIZE + reg); > + return ipmmu_read(domain->root, domain->context_id * IM_CTX_SIZE + reg); > } > > static void ipmmu_ctx_write(struct ipmmu_vmsa_domain *domain, unsigned int reg, > u32 data) > { > - ipmmu_write(domain->mmu, domain->context_id * IM_CTX_SIZE + reg, data); > + ipmmu_write(domain->root, domain->context_id * IM_CTX_SIZE + reg, data); > } > > /* ----------------------------------------------------------------------------- > @@ -360,7 +401,7 @@ static int ipmmu_domain_init_context(str > * TODO: Add support for coherent walk through CCI with DVM and remove > * cache handling. For now, delegate it to the io-pgtable code. > */ > - domain->cfg.iommu_dev = domain->mmu->dev; > + domain->cfg.iommu_dev = domain->root->dev; > > domain->iop = alloc_io_pgtable_ops(ARM_32_LPAE_S1, &domain->cfg, > domain); > @@ -370,7 +411,7 @@ static int ipmmu_domain_init_context(str > /* > * Find an unused context. > */ > - ret = ipmmu_domain_allocate_context(domain->mmu, domain); > + ret = ipmmu_domain_allocate_context(domain->root, domain); > if (ret == IPMMU_CTX_MAX) { > free_io_pgtable_ops(domain->iop); > return -EBUSY; > @@ -441,7 +482,7 @@ static void ipmmu_domain_destroy_context > */ > ipmmu_ctx_write(domain, IMCTR, IMCTR_FLUSH); > ipmmu_tlb_sync(domain); > - ipmmu_domain_free_context(domain->mmu, domain->context_id); > + ipmmu_domain_free_context(domain->root, domain->context_id); > } > > /* ----------------------------------------------------------------------------- > @@ -555,7 +596,7 @@ static int ipmmu_attach_device(struct io > { > struct ipmmu_vmsa_iommu_priv *priv = to_priv(dev); > struct iommu_fwspec *fwspec = dev->iommu_fwspec; > - struct ipmmu_vmsa_device *mmu = priv->mmu; > + struct ipmmu_vmsa_device *root, *mmu = priv->mmu; > struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain); > unsigned long flags; > unsigned int i; > @@ -566,11 +607,18 @@ static int ipmmu_attach_device(struct io > return -ENXIO; > } > > + root = ipmmu_find_root(priv->mmu); > + if (!root) { > + dev_err(dev, "Unable to locate root IPMMU\n"); > + return -EAGAIN; > + } > + > spin_lock_irqsave(&domain->lock, flags); > > if (!domain->mmu) { > /* The domain hasn't been used yet, initialize it. */ > domain->mmu = mmu; > + domain->root = root; > ret = ipmmu_domain_init_context(domain); > } else if (domain->mmu != mmu) { > /* > @@ -911,6 +959,7 @@ static void ipmmu_device_reset(struct ip > > static const struct ipmmu_features ipmmu_features_default = { > .use_ns_alias_offset = true, > + .has_cache_leaf_nodes = false, > }; > > static const struct of_device_id ipmmu_of_ids[] = { > @@ -965,19 +1014,31 @@ static int ipmmu_probe(struct platform_d > mmu->base += IM_NS_ALIAS_OFFSET; > > irq = platform_get_irq(pdev, 0); > - if (irq < 0) { > - dev_err(&pdev->dev, "no IRQ found\n"); > - return irq; > - } > > - ret = devm_request_irq(&pdev->dev, irq, ipmmu_irq, 0, > - dev_name(&pdev->dev), mmu); > - if (ret < 0) { > - dev_err(&pdev->dev, "failed to request IRQ %d\n", irq); > - return ret; > - } > + /* > + * Determine if this IPMMU instance is a leaf device by checking > + * if the renesas,ipmmu-main property exists or not. > + */ > + if (mmu->features->has_cache_leaf_nodes && > + of_find_property(pdev->dev.of_node, "renesas,ipmmu-main", NULL)) > + mmu->is_leaf = true; Given my previous comments: if (mmu->features->has_cache_leaf_nodes) { root_np = of_parse_phandle(pdev->dev.of_node, "renesas,ipmmu-main", 0) if (root_np) { root_pdev = of_find_device_by_phandle(root_np); mmu->root = platform_get_drvdata(root_pdev); } else { mmu->root = mmu; } } or something along those lines? Robin. > + > + /* Root devices have mandatory IRQs */ > + if (ipmmu_is_root(mmu)) { > + if (irq < 0) { > + dev_err(&pdev->dev, "no IRQ found\n"); > + return irq; > + } > > - ipmmu_device_reset(mmu); > + ret = devm_request_irq(&pdev->dev, irq, ipmmu_irq, 0, > + dev_name(&pdev->dev), mmu); > + if (ret < 0) { > + dev_err(&pdev->dev, "failed to request IRQ %d\n", irq); > + return ret; > + } > + > + ipmmu_device_reset(mmu); > + } > > ret = iommu_device_register(&mmu->iommu); > if (ret) >