Re: [PATCH v15 10/12] swiotlb: Add restricted DMA pool initialization
On Thu, Jun 24, 2021 at 6:59 PM Claire Chang wrote:
>
> Add the initialization function to create restricted DMA pools from
> matching reserved-memory nodes.
>
> Regardless of swiotlb setting, the restricted DMA pool is preferred if
> available.
>
> The restricted DMA pools provide a basic level of protection against the
> DMA overwriting buffer contents at unexpected times. However, to protect
> against general data leakage and system memory corruption, the system
> needs to provide a way to lock down the memory access, e.g., MPU.
> +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;
> +
> + /*
> +* 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) {
Can it be rather
if (mem)
goto out_assign;
or so?
> + mem = kzalloc(struct_size(mem, slots, nslabs), GFP_KERNEL);
> + if (!mem)
> + return -ENOMEM;
> +
> + set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),
> +rmem->size >> PAGE_SHIFT);
Below you are using a macro from pfn.h, but not here, I think it's PFN_DOWN().
> + swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false);
> + mem->force_bounce = true;
> + mem->for_alloc = true;
> +
> + rmem->priv = mem;
> +
> + if (IS_ENABLED(CONFIG_DEBUG_FS)) {
> + mem->debugfs =
> + debugfs_create_dir(rmem->name, debugfs_dir);
> + swiotlb_create_debugfs_files(mem);
> + }
> + }
> +
> + dev->dma_io_tlb_mem = mem;
> +
> + return 0;
> +}
> +
> +static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
> + struct device *dev)
> +{
> + dev->dma_io_tlb_mem = io_tlb_default_mem;
> +}
> +
> +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;
> +
> + if (PageHighMem(pfn_to_page(PHYS_PFN(rmem->base {
> + pr_err("Restricted DMA pool must be accessible within the
> linear mapping.");
> + return -EINVAL;
> + }
> +
> + rmem->ops = _swiotlb_ops;
> + pr_info("Reserved memory: created restricted DMA pool at %pa, size
> %ld MiB\n",
> + >base, (unsigned long)rmem->size / SZ_1M);
Oh là là, besides explicit casting that I believe can be avoided, %ld
!= unsigned long. Can you check the printk-formats.rst document?
> + return 0;
> +}
> +
> +RESERVEDMEM_OF_DECLARE(dma, "restricted-dma-pool", rmem_swiotlb_setup);
> #endif /* CONFIG_DMA_RESTRICTED_POOL */
--
With Best Regards,
Andy Shevchenko
Re: [PATCH v15 10/12] swiotlb: Add restricted DMA pool initialization
On Tue, Aug 24, 2021 at 10:26 PM Guenter Roeck wrote: > > Hi Claire, > > On Thu, Jun 24, 2021 at 11:55:24PM +0800, Claire Chang wrote: > > Add the initialization function to create restricted DMA pools from > > matching reserved-memory nodes. > > > > Regardless of swiotlb setting, the restricted DMA pool is preferred if > > available. > > > > The restricted DMA pools provide a basic level of protection against the > > DMA overwriting buffer contents at unexpected times. However, to protect > > against general data leakage and system memory corruption, the system > > needs to provide a way to lock down the memory access, e.g., MPU. > > > > Signed-off-by: Claire Chang > > Reviewed-by: Christoph Hellwig > > Tested-by: Stefano Stabellini > > Tested-by: Will Deacon > > --- > > include/linux/swiotlb.h | 3 +- > > kernel/dma/Kconfig | 14 > > kernel/dma/swiotlb.c| 76 + > > 3 files changed, 92 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > > index 3b9454d1e498..39284ff2a6cd 100644 > > --- a/include/linux/swiotlb.h > > +++ b/include/linux/swiotlb.h > > @@ -73,7 +73,8 @@ 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/Kconfig b/kernel/dma/Kconfig > > index 77b405508743..3e961dc39634 100644 > > --- a/kernel/dma/Kconfig > > +++ b/kernel/dma/Kconfig > > @@ -80,6 +80,20 @@ config SWIOTLB > > bool > > select NEED_DMA_MAP_STATE > > > > +config DMA_RESTRICTED_POOL > > + bool "DMA Restricted Pool" > > + depends on OF && OF_RESERVED_MEM > > + select SWIOTLB > > This makes SWIOTLB user configurable, which in turn results in > > mips64-linux-ld: arch/mips/kernel/setup.o: in function `arch_mem_init': > setup.c:(.init.text+0x19c8): undefined reference to `plat_swiotlb_setup' > make[1]: *** [Makefile:1280: vmlinux] Error 1 > > when building mips:allmodconfig. > > Should this possibly be "depends on SWIOTLB" ? Patch is sent here: https://lkml.org/lkml/2021/8/26/932 > > Thanks, > Guenter Thanks, Claire
Re: [PATCH v15 10/12] swiotlb: Add restricted DMA pool initialization
Hi Claire, On Thu, Jun 24, 2021 at 11:55:24PM +0800, Claire Chang wrote: > Add the initialization function to create restricted DMA pools from > matching reserved-memory nodes. > > Regardless of swiotlb setting, the restricted DMA pool is preferred if > available. > > The restricted DMA pools provide a basic level of protection against the > DMA overwriting buffer contents at unexpected times. However, to protect > against general data leakage and system memory corruption, the system > needs to provide a way to lock down the memory access, e.g., MPU. > > Signed-off-by: Claire Chang > Reviewed-by: Christoph Hellwig > Tested-by: Stefano Stabellini > Tested-by: Will Deacon > --- > include/linux/swiotlb.h | 3 +- > kernel/dma/Kconfig | 14 > kernel/dma/swiotlb.c| 76 + > 3 files changed, 92 insertions(+), 1 deletion(-) > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 3b9454d1e498..39284ff2a6cd 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -73,7 +73,8 @@ 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/Kconfig b/kernel/dma/Kconfig > index 77b405508743..3e961dc39634 100644 > --- a/kernel/dma/Kconfig > +++ b/kernel/dma/Kconfig > @@ -80,6 +80,20 @@ config SWIOTLB > bool > select NEED_DMA_MAP_STATE > > +config DMA_RESTRICTED_POOL > + bool "DMA Restricted Pool" > + depends on OF && OF_RESERVED_MEM > + select SWIOTLB This makes SWIOTLB user configurable, which in turn results in mips64-linux-ld: arch/mips/kernel/setup.o: in function `arch_mem_init': setup.c:(.init.text+0x19c8): undefined reference to `plat_swiotlb_setup' make[1]: *** [Makefile:1280: vmlinux] Error 1 when building mips:allmodconfig. Should this possibly be "depends on SWIOTLB" ? Thanks, Guenter
[PATCH v15 10/12] swiotlb: Add restricted DMA pool initialization
Add the initialization function to create restricted DMA pools from
matching reserved-memory nodes.
Regardless of swiotlb setting, the restricted DMA pool is preferred if
available.
The restricted DMA pools provide a basic level of protection against the
DMA overwriting buffer contents at unexpected times. However, to protect
against general data leakage and system memory corruption, the system
needs to provide a way to lock down the memory access, e.g., MPU.
Signed-off-by: Claire Chang
Reviewed-by: Christoph Hellwig
Tested-by: Stefano Stabellini
Tested-by: Will Deacon
---
include/linux/swiotlb.h | 3 +-
kernel/dma/Kconfig | 14
kernel/dma/swiotlb.c| 76 +
3 files changed, 92 insertions(+), 1 deletion(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 3b9454d1e498..39284ff2a6cd 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -73,7 +73,8 @@ 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/Kconfig b/kernel/dma/Kconfig
index 77b405508743..3e961dc39634 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -80,6 +80,20 @@ config SWIOTLB
bool
select NEED_DMA_MAP_STATE
+config DMA_RESTRICTED_POOL
+ bool "DMA Restricted Pool"
+ depends on OF && OF_RESERVED_MEM
+ select SWIOTLB
+ help
+ This enables support for restricted DMA pools which provide a level of
+ DMA memory protection on systems with limited hardware protection
+ capabilities, such as those lacking an IOMMU.
+
+ For more information see
+
+ and .
+ If unsure, say "n".
+
#
# Should be selected if we can mmap non-coherent mappings to userspace.
# The only thing that is really required is a way to set an uncached bit
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 6a7c6e30eb4b..3baf49c9b766 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
@@ -737,4 +744,73 @@ bool swiotlb_free(struct device *dev, struct page *page,
size_t size)
return true;
}
+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;
+
+ /*
+* 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;
+
+ set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),
+rmem->size >> PAGE_SHIFT);
+ swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false);
+ mem->force_bounce = true;
+ mem->for_alloc = true;
+
+ rmem->priv = mem;
+
+ if (IS_ENABLED(CONFIG_DEBUG_FS)) {
+ mem->debugfs =
+ debugfs_create_dir(rmem->name, debugfs_dir);
+ swiotlb_create_debugfs_files(mem);
+ }
+ }
+
+ dev->dma_io_tlb_mem = mem;
+
+ return 0;
+}
+
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
+ struct device *dev)
+{
+ dev->dma_io_tlb_mem = io_tlb_default_mem;
+}
+
+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;
+
+ if (PageHighMem(pfn_to_page(PHYS_PFN(rmem->base {
+ pr_err("Restricted DMA pool must be accessible within the
linear mapping.");
+ return
