Re: [RFC PATCH 4/4] dma-buf: heaps: add Linaro restricted dmabuf heap support

[Jens Wiklander <jens.wiklander@linaro.org>]

On Tue, Sep 3, 2024 at 7:50 PM T.J. Mercier <tjmercier@google.com> wrote:
>
> On Fri, Aug 30, 2024 at 12:04 AM Jens Wiklander
> <jens.wiklander@linaro.org> wrote:
> >
> > Add a Linaro restricted heap using the linaro,restricted-heap bindings
> > implemented based on the generic restricted heap.
> >
> > The bindings defines a range of physical restricted memory. The heap
> > manages this address range using genalloc. The allocated dma-buf file
> > descriptor can later be registered with the TEE subsystem for later use
> > via Trusted Applications in the secure world.
> >
> > Co-developed-by: Olivier Masse <olivier.masse@nxp.com>
> > Signed-off-by: Olivier Masse <olivier.masse@nxp.com>
> > Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
> > ---
> >  drivers/dma-buf/heaps/Kconfig                 |  10 ++
> >  drivers/dma-buf/heaps/Makefile                |   1 +
> >  .../dma-buf/heaps/restricted_heap_linaro.c    | 165 ++++++++++++++++++
> >  3 files changed, 176 insertions(+)
> >  create mode 100644 drivers/dma-buf/heaps/restricted_heap_linaro.c
> >
> > diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> > index 58903bc62ac8..82e2c5d09242 100644
> > --- a/drivers/dma-buf/heaps/Kconfig
> > +++ b/drivers/dma-buf/heaps/Kconfig
> > @@ -28,3 +28,13 @@ config DMABUF_HEAPS_RESTRICTED_MTK
> >         help
> >           Enable restricted dma-buf heaps for MediaTek platform. This heap is backed by
> >           TEE client interfaces. If in doubt, say N.
> > +
> > +config DMABUF_HEAPS_RESTRICTED_LINARO
> > +       bool "Linaro DMA-BUF Restricted Heap"
> > +       depends on DMABUF_HEAPS_RESTRICTED
> > +       help
> > +         Choose this option to enable the Linaro restricted dma-buf heap.
> > +         The restricted heap pools are defined according to the DT. Heaps
> > +         are allocated in the pools using gen allocater.
> > +         If in doubt, say N.
> > +
> > diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> > index 0028aa9d875f..66b2f67c47b5 100644
> > --- a/drivers/dma-buf/heaps/Makefile
> > +++ b/drivers/dma-buf/heaps/Makefile
> > @@ -2,4 +2,5 @@
> >  obj-$(CONFIG_DMABUF_HEAPS_CMA)         += cma_heap.o
> >  obj-$(CONFIG_DMABUF_HEAPS_RESTRICTED)  += restricted_heap.o
> >  obj-$(CONFIG_DMABUF_HEAPS_RESTRICTED_MTK)      += restricted_heap_mtk.o
> > +obj-$(CONFIG_DMABUF_HEAPS_RESTRICTED_LINARO)   += restricted_heap_linaro.o
> >  obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)      += system_heap.o
> > diff --git a/drivers/dma-buf/heaps/restricted_heap_linaro.c b/drivers/dma-buf/heaps/restricted_heap_linaro.c
> > new file mode 100644
> > index 000000000000..4b08ed514023
> > --- /dev/null
> > +++ b/drivers/dma-buf/heaps/restricted_heap_linaro.c
> > @@ -0,0 +1,165 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * DMABUF secure heap exporter
> > + *
> > + * Copyright 2021 NXP.
> > + * Copyright 2024 Linaro Limited.
> > + */
> > +
> > +#define pr_fmt(fmt)     "rheap_linaro: " fmt
> > +
> > +#include <linux/dma-buf.h>
> > +#include <linux/err.h>
> > +#include <linux/genalloc.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_fdt.h>
> > +#include <linux/of_reserved_mem.h>
> > +#include <linux/scatterlist.h>
> > +#include <linux/slab.h>
> > +
> > +#include "restricted_heap.h"
> > +
> > +#define MAX_HEAP_COUNT 2
>
> Are multiple supported because of what Cyrille mentioned here about permissions?
> https://lore.kernel.org/lkml/DBBPR04MB7514E006455AEA407041E4F788709@DBBPR04MB7514.eurprd04.prod.outlook.com/

Yes, I kept that as is.

>
> So this is just some arbitrary limit? I'd prefer to have some sort of
> documentation about this.

How about removing the limit and using dynamic allocation instead?

Thanks,
Jens

>
>
> > +#define HEAP_NAME_LEN  32
> > +
> > +struct resmem_restricted {
> > +       phys_addr_t base;
> > +       phys_addr_t size;
> > +
> > +       char name[HEAP_NAME_LEN];
> > +
> > +       bool no_map;
> > +};
> > +
> > +static struct resmem_restricted restricted_data[MAX_HEAP_COUNT] = {0};
> > +static unsigned int restricted_data_count;
> > +
> > +static int linaro_restricted_memory_allocate(struct restricted_heap *heap,
> > +                                            struct restricted_buffer *buf)
> > +{
> > +       struct gen_pool *pool = heap->priv_data;
> > +       unsigned long pa;
> > +       int ret;
> > +
> > +       buf->size = ALIGN(buf->size, PAGE_SIZE);
> > +       pa = gen_pool_alloc(pool, buf->size);
> > +       if (!pa)
> > +               return -ENOMEM;
> > +
> > +       ret = sg_alloc_table(&buf->sg_table, 1, GFP_KERNEL);
> > +       if (ret) {
> > +               gen_pool_free(pool, pa, buf->size);
> > +               return ret;
> > +       }
> > +
> > +       sg_set_page(buf->sg_table.sgl, phys_to_page(pa), buf->size, 0);
> > +
> > +       return 0;
> > +}
> > +
> > +static void linaro_restricted_memory_free(struct restricted_heap *heap,
> > +                                         struct restricted_buffer *buf)
> > +{
> > +       struct gen_pool *pool = heap->priv_data;
> > +       struct scatterlist *sg;
> > +       unsigned int i;
> > +
> > +       for_each_sg(buf->sg_table.sgl, sg, buf->sg_table.nents, i)
> > +               gen_pool_free(pool, page_to_phys(sg_page(sg)), sg->length);
> > +       sg_free_table(&buf->sg_table);
> > +}
> > +
> > +static const struct restricted_heap_ops linaro_restricted_heap_ops = {
> > +       .alloc = linaro_restricted_memory_allocate,
> > +       .free = linaro_restricted_memory_free,
> > +};
> > +
> > +static int add_heap(struct resmem_restricted *mem)
> > +{
> > +       struct restricted_heap *heap;
> > +       struct gen_pool *pool;
> > +       int ret;
> > +
> > +       if (mem->base == 0 || mem->size == 0) {
> > +               pr_err("restricted_data base or size is not correct\n");
> > +               return -EINVAL;
> > +       }
> > +
> > +       heap = kzalloc(sizeof(*heap), GFP_KERNEL);
> > +       if (!heap)
> > +               return -ENOMEM;
> > +
> > +       pool = gen_pool_create(PAGE_SHIFT, -1);
> > +       if (!pool) {
> > +               ret = -ENOMEM;
> > +               goto err_free_heap;
> > +       }
> > +
> > +       ret = gen_pool_add(pool, mem->base, mem->size, -1);
> > +       if (ret)
> > +               goto err_free_pool;
> > +
> > +       heap->no_map = mem->no_map;
> > +       heap->priv_data = pool;
> > +       heap->name = mem->name;
> > +       heap->ops = &linaro_restricted_heap_ops;
> > +
> > +       ret = restricted_heap_add(heap);
> > +       if (ret)
> > +               goto err_free_pool;
> > +
> > +       return 0;
> > +
> > +err_free_pool:
> > +       gen_pool_destroy(pool);
> > +err_free_heap:
> > +       kfree(heap);
> > +
> > +       return ret;
> > +}
> > +
> > +static int __init rmem_restricted_heap_setup(struct reserved_mem *rmem)
> > +{
> > +       size_t len = HEAP_NAME_LEN;
> > +       const char *s;
> > +       bool no_map;
> > +
> > +       if (WARN_ONCE(restricted_data_count >= MAX_HEAP_COUNT,
> > +                     "Cannot handle more than %u restricted heaps\n",
> > +                     MAX_HEAP_COUNT))
> > +               return -EINVAL;
> > +
> > +       no_map = of_get_flat_dt_prop(rmem->fdt_node, "no-map", NULL);
> > +       s = strchr(rmem->name, '@');
> > +       if (s)
> > +               len = umin(s - rmem->name + 1, len);
> > +
> > +       restricted_data[restricted_data_count].base = rmem->base;
> > +       restricted_data[restricted_data_count].size = rmem->size;
> > +       restricted_data[restricted_data_count].no_map = no_map;
> > +       strscpy(restricted_data[restricted_data_count].name, rmem->name, len);
> > +
> > +       restricted_data_count++;
> > +       return 0;
> > +}
> > +
> > +RESERVEDMEM_OF_DECLARE(linaro_restricted_heap, "linaro,restricted-heap",
> > +                      rmem_restricted_heap_setup);
> > +
> > +static int linaro_restricted_heap_init(void)
> > +{
> > +       unsigned int i;
> > +       int ret;
> > +
> > +       for (i = 0; i < restricted_data_count; i++) {
> > +               ret = add_heap(&restricted_data[i]);
> > +               if (ret)
> > +                       return ret;
> > +       }
> > +       return 0;
> > +}
> > +
> > +module_init(linaro_restricted_heap_init);
> > +MODULE_DESCRIPTION("Linaro Restricted Heap Driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.34.1
> >