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[209.85.166.173]) by smtp.gmail.com with ESMTPSA id b12sm176786iln.58.2021.04.26.09.45.23 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Apr 2021 09:45:23 -0700 (PDT) Received: by mail-il1-f173.google.com with SMTP id c15so47179988ilj.1 for ; Mon, 26 Apr 2021 09:45:23 -0700 (PDT) X-Received: by 2002:a5d:8c82:: with SMTP id g2mr15143365ion.34.1619455049397; Mon, 26 Apr 2021 09:37:29 -0700 (PDT) MIME-Version: 1.0 References: <20210422081508.3942748-1-tientzu@chromium.org> <20210422081508.3942748-6-tientzu@chromium.org> In-Reply-To: From: Claire Chang Date: Tue, 27 Apr 2021 00:37:18 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 05/16] swiotlb: Add restricted DMA pool initialization To: Steven Price Cc: Joerg Roedel , Will Deacon , Frank Rowand , Konrad Rzeszutek Wilk , boris.ostrovsky@oracle.com, jgross@suse.com, Christoph Hellwig , Marek Szyprowski , benh@kernel.crashing.org, paulus@samba.org, "list@263.net:IOMMU DRIVERS" , sstabellini@kernel.org, Robin Murphy , grant.likely@arm.com, xypron.glpk@gmx.de, Thierry Reding , mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, Greg KH , Saravana Kannan , "Rafael J . Wysocki" , heikki.krogerus@linux.intel.com, Andy Shevchenko , Randy Dunlap , Dan Williams , Bartosz Golaszewski , linux-devicetree , lkml , linuxppc-dev@lists.ozlabs.org, xen-devel@lists.xenproject.org, Nicolas Boichat , Jim Quinlan , Tomasz Figa , bskeggs@redhat.com, Bjorn Helgaas , chris@chris-wilson.co.uk, Daniel Vetter , airlied@linux.ie, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, Jianxiong Gao , joonas.lahtinen@linux.intel.com, linux-pci@vger.kernel.org, maarten.lankhorst@linux.intel.com, matthew.auld@intel.com, nouveau@lists.freedesktop.org, rodrigo.vivi@intel.com, thomas.hellstrom@linux.intel.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, Apr 23, 2021 at 7:34 PM Steven Price wrote: > > On 22/04/2021 09:14, Claire Chang wrote: > > Add the initialization function to create restricted DMA pools from > > matching reserved-memory nodes. > > > > Signed-off-by: Claire Chang > > --- > > include/linux/device.h | 4 +++ > > include/linux/swiotlb.h | 3 +- > > kernel/dma/swiotlb.c | 80 +++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 86 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/device.h b/include/linux/device.h > > index 38a2071cf776..4987608ea4ff 100644 > > --- a/include/linux/device.h > > +++ b/include/linux/device.h > > @@ -416,6 +416,7 @@ struct dev_links_info { > > * @dma_pools: Dma pools (if dma'ble device). > > * @dma_mem: Internal for coherent mem override. > > * @cma_area: Contiguous memory area for dma allocations > > + * @dma_io_tlb_mem: Internal for swiotlb io_tlb_mem override. > > * @archdata: For arch-specific additions. > > * @of_node: Associated device tree node. > > * @fwnode: Associated device node supplied by platform firmware. > > @@ -521,6 +522,9 @@ struct device { > > #ifdef CONFIG_DMA_CMA > > struct cma *cma_area; /* contiguous memory area for dma > > allocations */ > > +#endif > > +#ifdef CONFIG_DMA_RESTRICTED_POOL > > + struct io_tlb_mem *dma_io_tlb_mem; > > #endif > > /* arch specific additions */ > > struct dev_archdata archdata; > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > > index 216854a5e513..03ad6e3b4056 100644 > > --- a/include/linux/swiotlb.h > > +++ b/include/linux/swiotlb.h > > @@ -72,7 +72,8 @@ extern enum swiotlb_force swiotlb_force; > > * range check to see if the memory was in fact allocated by this > > * API. > > * @nslabs: The number of IO TLB blocks (in groups of 64) between @start and > > - * @end. This is command line adjustable via setup_io_tlb_npages. > > + * @end. For default swiotlb, this is command line adjustable via > > + * setup_io_tlb_npages. > > * @used: The number of used IO TLB block. > > * @list: The free list describing the number of free entries available > > * from each index. > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > > index 57a9adb920bf..ffbb8724e06c 100644 > > --- a/kernel/dma/swiotlb.c > > +++ b/kernel/dma/swiotlb.c > > @@ -39,6 +39,13 @@ > > #ifdef CONFIG_DEBUG_FS > > #include > > #endif > > +#ifdef CONFIG_DMA_RESTRICTED_POOL > > +#include > > +#include > > +#include > > +#include > > +#include > > +#endif > > > > #include > > #include > > @@ -681,3 +688,76 @@ static int __init swiotlb_create_default_debugfs(void) > > late_initcall(swiotlb_create_default_debugfs); > > > > #endif > > + > > +#ifdef CONFIG_DMA_RESTRICTED_POOL > > +static int rmem_swiotlb_device_init(struct reserved_mem *rmem, > > + struct device *dev) > > +{ > > + struct io_tlb_mem *mem = rmem->priv; > > + unsigned long nslabs = rmem->size >> IO_TLB_SHIFT; > > + > > + if (dev->dma_io_tlb_mem) > > + return 0; > > + > > + /* Since multiple devices can share the same pool, the private data, > > + * io_tlb_mem struct, will be initialized by the first device attached > > + * to it. > > + */ > > + if (!mem) { > > + mem = kzalloc(struct_size(mem, slots, nslabs), GFP_KERNEL); > > + if (!mem) > > + return -ENOMEM; > > +#ifdef CONFIG_ARM > > + if (!PageHighMem(pfn_to_page(PHYS_PFN(rmem->base)))) { > > + kfree(mem); > > + return -EINVAL; > > + } > > +#endif /* CONFIG_ARM */ > > + swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false); > > + > > + rmem->priv = mem; > > + } > > + > > +#ifdef CONFIG_DEBUG_FS > > + if (!io_tlb_default_mem->debugfs) > > + io_tlb_default_mem->debugfs = > > + debugfs_create_dir("swiotlb", NULL); > > At this point it's possible for io_tlb_default_mem to be NULL, leading > to a splat. Thanks for pointing this out. > > But even then if it's not and we have the situation where debugfs==NULL > then the debugfs_create_dir() here will cause a subsequent attempt in > swiotlb_create_debugfs() to fail (directory already exists) leading to > mem->debugfs being assigned an error value. I suspect the creation of > the debugfs directory needs to be separated from io_tlb_default_mem > being set. debugfs creation should move into the if (!mem) {...} above to avoid duplication. I think having a separated struct dentry pointer for the default debugfs should be enough? if (!debugfs) debugfs = debugfs_create_dir("swiotlb", NULL); swiotlb_create_debugfs(mem, rmem->name, debugfs); > > Other than that I gave this series a go with our prototype of Arm's > Confidential Computer Architecture[1] - since the majority of the > guest's memory is protected from the host the restricted DMA pool allows > (only) a small area to be shared with the host. > > After fixing (well hacking round) the above it all seems to be working > fine with virtio drivers. > > Thanks, > > Steve > > [1] > https://www.arm.com/why-arm/architecture/security-features/arm-confidential-compute-architecture