Claire Chang
2021-Apr-22 08:14 UTC
[Nouveau] [PATCH v5 05/16] swiotlb: Add restricted DMA pool initialization
Add the initialization function to create restricted DMA pools from
matching reserved-memory nodes.
Signed-off-by: Claire Chang <tientzu at chromium.org>
---
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 <linux/debugfs.h>
#endif
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/slab.h>
+#endif
#include <asm/io.h>
#include <asm/dma.h>
@@ -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);
+
+ swiotlb_create_debugfs(mem, rmem->name, io_tlb_default_mem->debugfs);
+#endif /* CONFIG_DEBUG_FS */
+
+ dev->dma_io_tlb_mem = mem;
+
+ return 0;
+}
+
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
+ struct device *dev)
+{
+ if (dev)
+ dev->dma_io_tlb_mem = NULL;
+}
+
+static const struct reserved_mem_ops rmem_swiotlb_ops = {
+ .device_init = rmem_swiotlb_device_init,
+ .device_release = rmem_swiotlb_device_release,
+};
+
+static int __init rmem_swiotlb_setup(struct reserved_mem *rmem)
+{
+ unsigned long node = rmem->fdt_node;
+
+ if (of_get_flat_dt_prop(node, "reusable", NULL) ||
+ of_get_flat_dt_prop(node, "linux,cma-default", NULL) ||
+ of_get_flat_dt_prop(node, "linux,dma-default", NULL) ||
+ of_get_flat_dt_prop(node, "no-map", NULL))
+ return -EINVAL;
+
+ rmem->ops = &rmem_swiotlb_ops;
+ pr_info("Reserved memory: created device swiotlb memory pool at %pa, size
%ld MiB\n",
+ &rmem->base, (unsigned long)rmem->size / SZ_1M);
+ return 0;
+}
+
+RESERVEDMEM_OF_DECLARE(dma, "restricted-dma-pool",
rmem_swiotlb_setup);
+#endif /* CONFIG_DMA_RESTRICTED_POOL */
--
2.31.1.368.gbe11c130af-goog
Steven Price
2021-Apr-23 11:34 UTC
[Nouveau] [PATCH v5 05/16] swiotlb: Add restricted DMA pool initialization
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 <tientzu at chromium.org> > --- > 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 <linux/debugfs.h> > #endif > +#ifdef CONFIG_DMA_RESTRICTED_POOL > +#include <linux/io.h> > +#include <linux/of.h> > +#include <linux/of_fdt.h> > +#include <linux/of_reserved_mem.h> > +#include <linux/slab.h> > +#endif > > #include <asm/io.h> > #include <asm/dma.h> > @@ -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. 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. 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