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Message-ID: <dbb4b384cba026077dd2d89965dff85aa79ed301.camel@nxp.com>
Date: Fri, 5 Aug 2022 14:06:24 +0000
From: Olivier Masse <olivier.masse@....com>
To: "brian.starkey@....com" <brian.starkey@....com>
CC: "sumit.semwal@...aro.org" <sumit.semwal@...aro.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
"christian.koenig@....com" <christian.koenig@....com>,
"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"nd@....com" <nd@....com>,
Clément Faure <clement.faure@....com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"benjamin.gaignard@...labora.com" <benjamin.gaignard@...labora.com>
Subject: Re: [EXT] Re: [PATCH 3/5] dma-buf: heaps: add Linaro secure dmabuf
heap support
Hi Brian,
Sorry for pushing all the patches again, but I've done some cleanup
regarding your comments.
secure-heap are now protected by default and no mapping could be done
for the CPU.
deferred-free is no more needed.
useless page pool code removed too.
Best regards,
Olivier
On mer., 2022-08-03 at 13:37 +0100, Brian Starkey wrote:
> Caution: EXT Email
>
> Hi,
>
> On Wed, Aug 03, 2022 at 11:07:54AM +0000, Olivier Masse wrote:
> > Hi Brian,
> >
> > Thanks for your comments, please find my reply below.
> >
> > On mar., 2022-08-02 at 15:39 +0100, Brian Starkey wrote:
> > > Caution: EXT Email
> > >
> > > Hi Olivier,
> > >
> > > Some comments below as I mentioned off-list.
> > >
> > > One additional point: some devices need to know if a buffer is
> > > protected, so that they can configure registers appropriately to
> > > make
> > > use of that protected buffer. There was previously a discussion
> > > about
> > > adding a flag to a dma_buf to indicate that it is allocated from
> > > protected memory[1].
> > >
> > > [1]
> > >
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Farchives%2Fdri-devel%2F2019-September%2F238059.html&data=05%7C01%7Colivier.masse%40nxp.com%7Cafa24901ad92491c9a6a08da754d00b5%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637951270862339002%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=LoQfoWYr0yHvTWa2tth9XOm2PACji4ATHnx3BRNKnJM%3D&reserved=0
> > >
> > >
> >
> > Interesting, could we introduce is_protected 1-bit flag into struct
> > dma_buf ?
>
> That was the earlier proposal, yeah.
>
> > struct dma_buf_ops.map_dma_buf and struct dma_buf_ops.unmap_dma_buf
> > could become optional for such buffer ?
> >
>
> map_dma_buf and unmap_dma_buf are needed to give devices access to
> the
> dma-buf, I don't think they should become optional.
>
> Mapping to the CPU maybe should be optional/disallowed for protected
> buffers.
>
> > > On Tue, Aug 02, 2022 at 11:58:41AM +0200, Olivier Masse wrote:
> > > > add Linaro secure heap bindings: linaro,secure-heap
> > > > use genalloc to allocate/free buffer from buffer pool.
> > > > buffer pool info is from dts.
> > > > use sg_table instore the allocated memory info, the length of
> > > > sg_table is 1.
> > > > implement secure_heap_buf_ops to implement buffer share in
> > > > difference device:
> > > > 1. Userspace passes this fd to all drivers it wants this buffer
> > > > to share with: First the filedescriptor is converted to a
> > > > &dma_buf
> > > > using
> > > > dma_buf_get(). Then the buffer is attached to the device using
> > > > dma_buf_attach().
> > > > 2. Once the buffer is attached to all devices userspace can
> > > > initiate DMA
> > > > access to the shared buffer. In the kernel this is done by
> > > > calling
> > > > dma_buf_map_attachment()
> > > > 3. get sg_table with dma_buf_map_attachment in difference
> > > > device.
> > > >
> > > > Signed-off-by: Olivier Masse <olivier.masse@....com>
> > > > ---
> > > > drivers/dma-buf/heaps/Kconfig | 21 +-
> > > > drivers/dma-buf/heaps/Makefile | 1 +
> > > > drivers/dma-buf/heaps/secure_heap.c | 588
> > > > ++++++++++++++++++++++++++++
> > > > 3 files changed, 606 insertions(+), 4 deletions(-)
> > > > create mode 100644 drivers/dma-buf/heaps/secure_heap.c
> > > >
> > > > diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-
> > > > buf/heaps/Kconfig
> > > > index 6a33193a7b3e..b2406932192e 100644
> > > > --- a/drivers/dma-buf/heaps/Kconfig
> > > > +++ b/drivers/dma-buf/heaps/Kconfig
> > > > @@ -1,8 +1,12 @@
> > > > -config DMABUF_HEAPS_DEFERRED_FREE
> > > > - tristate
> > > > +menuconfig DMABUF_HEAPS_DEFERRED_FREE
> > > > + bool "DMA-BUF heaps deferred-free library"
> > > > + help
> > > > + Choose this option to enable the DMA-BUF heaps
> > > > deferred-
> > > > free library.
> > > >
> > > > -config DMABUF_HEAPS_PAGE_POOL
> > > > - tristate
> > > > +menuconfig DMABUF_HEAPS_PAGE_POOL
> > > > + bool "DMA-BUF heaps page-pool library"
> > > > + help
> > > > + Choose this option to enable the DMA-BUF heaps page-
> > > > pool
> > > > library.
> > > >
> > > > config DMABUF_HEAPS_SYSTEM
> > > > bool "DMA-BUF System Heap"
> > > > @@ -26,3 +30,12 @@ config DMABUF_HEAPS_DSP
> > > > Choose this option to enable the dsp dmabuf heap.
> > > > The
> > > > dsp heap
> > > > is allocated by gen allocater. it's allocated
> > > > according
> > > > the dts.
> > > > If in doubt, say Y.
> > > > +
> > > > +config DMABUF_HEAPS_SECURE
> > > > + tristate "DMA-BUF Secure Heap"
> > > > + depends on DMABUF_HEAPS && DMABUF_HEAPS_DEFERRED_FREE
> > > > + help
> > > > + Choose this option to enable the secure dmabuf heap.
> > > > The
> > > > secure heap
> > > > + pools are defined according to the DT. Heaps are
> > > > allocated
> > > > + in the pools using gen allocater.
> > > > + If in doubt, say Y.
> > > > diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-
> > > > buf/heaps/Makefile
> > > > index e70722ea615e..08f6aa5919d1 100644
> > > > --- a/drivers/dma-buf/heaps/Makefile
> > > > +++ b/drivers/dma-buf/heaps/Makefile
> > > > @@ -4,3 +4,4 @@ obj-$(CONFIG_DMABUF_HEAPS_PAGE_POOL) +=
> > > > page_pool.o
> > > > obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
> > > > obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
> > > > obj-$(CONFIG_DMABUF_HEAPS_DSP) += dsp_heap.o
> > > > +obj-$(CONFIG_DMABUF_HEAPS_SECURE) += secure_heap.o
> > > > diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-
> > > > buf/heaps/secure_heap.c
> > > > new file mode 100644
> > > > index 000000000000..31aac5d050b4
> > > > --- /dev/null
> > > > +++ b/drivers/dma-buf/heaps/secure_heap.c
> > > > @@ -0,0 +1,588 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * DMABUF secure heap exporter
> > > > + *
> > > > + * Copyright 2021 NXP.
> > > > + */
> > > > +
> > > > +#include <linux/dma-buf.h>
> > > > +#include <linux/dma-heap.h>
> > > > +#include <linux/dma-mapping.h>
> > > > +#include <linux/err.h>
> > > > +#include <linux/genalloc.h>
> > > > +#include <linux/highmem.h>
> > > > +#include <linux/mm.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 <linux/vmalloc.h>
> > > > +
> > > > +#include "deferred-free-helper.h"
> > > > +#include "page_pool.h"
> > > > +
> > > > +#define MAX_SECURE_HEAP 2
> > > > +#define MAX_HEAP_NAME_LEN 32
> > > > +
> > > > +struct secure_heap_buffer {
> > > > + struct dma_heap *heap;
> > > > + struct list_head attachments;
> > > > + struct mutex lock;
> > > > + unsigned long len;
> > > > + struct sg_table sg_table;
> > > > + int vmap_cnt;
> > > > + struct deferred_freelist_item deferred_free;
> > > > + void *vaddr;
> > > > + bool uncached;
> > > > +};
> > > > +
> > > > +struct dma_heap_attachment {
> > > > + struct device *dev;
> > > > + struct sg_table *table;
> > > > + struct list_head list;
> > > > + bool no_map;
> > > > + bool mapped;
> > > > + bool uncached;
> > > > +};
> > >
> > > I think dma_heap_attachment should have a more specific name,
> > > otherwise it looks like some generic part of the dma_heap
> > > framework.
> >
> > ok, how about secure_heap_attachment which sound more logical ?
> >
>
> Yes that sounds better.
>
> > >
> > > > +
> > > > +struct secure_heap_info {
> > > > + struct gen_pool *pool;
> > > > +
> > > > + bool no_map;
> > > > +};
> > > > +
> > > > +struct rmem_secure {
> > > > + phys_addr_t base;
> > > > + phys_addr_t size;
> > > > +
> > > > + char name[MAX_HEAP_NAME_LEN];
> > > > +
> > > > + bool no_map;
> > > > +};
> > > > +
> > > > +static struct rmem_secure secure_data[MAX_SECURE_HEAP] = {0};
> > > > +static unsigned int secure_data_count;
> > > > +
> > > > +static struct sg_table *dup_sg_table(struct sg_table *table)
> > > > +{
> > > > + struct sg_table *new_table;
> > > > + int ret, i;
> > > > + struct scatterlist *sg, *new_sg;
> > > > +
> > > > + new_table = kzalloc(sizeof(*new_table), GFP_KERNEL);
> > > > + if (!new_table)
> > > > + return ERR_PTR(-ENOMEM);
> > > > +
> > > > + ret = sg_alloc_table(new_table, table->orig_nents,
> > > > GFP_KERNEL);
> > > > + if (ret) {
> > > > + kfree(new_table);
> > > > + return ERR_PTR(-ENOMEM);
> > > > + }
> > > > +
> > > > + new_sg = new_table->sgl;
> > > > + for_each_sgtable_sg(table, sg, i) {
> > > > + sg_set_page(new_sg, sg_page(sg), sg->length, sg-
> > > > > offset);
> > > >
> > > > + new_sg->dma_address = sg->dma_address;
> > > > +#ifdef CONFIG_NEED_SG_DMA_LENGTH
> > > > + new_sg->dma_length = sg->dma_length;
> > > > +#endif
> > > > + new_sg = sg_next(new_sg);
> > > > + }
> > > > +
> > > > + return new_table;
> > > > +}
> > > > +
> > > > +static int secure_heap_attach(struct dma_buf *dmabuf,
> > > > + struct dma_buf_attachment
> > > > *attachment)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + struct secure_heap_info *info =
> > > > dma_heap_get_drvdata(buffer-
> > > > > heap);
> > > >
> > > > + struct dma_heap_attachment *a;
> > > > + struct sg_table *table;
> > > > +
> > > > + a = kzalloc(sizeof(*a), GFP_KERNEL);
> > > > + if (!a)
> > > > + return -ENOMEM;
> > > > +
> > > > + table = dup_sg_table(&buffer->sg_table);
> > > > + if (IS_ERR(table)) {
> > > > + kfree(a);
> > > > + return -ENOMEM;
> > > > + }
> > > > +
> > > > + a->table = table;
> > > > + a->dev = attachment->dev;
> > > > + INIT_LIST_HEAD(&a->list);
> > > > + a->no_map = info->no_map;
> > > > + a->mapped = false;
> > > > + a->uncached = buffer->uncached;
> > > > + attachment->priv = a;
> > > > +
> > > > + mutex_lock(&buffer->lock);
> > > > + list_add(&a->list, &buffer->attachments);
> > > > + mutex_unlock(&buffer->lock);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static void secure_heap_detach(struct dma_buf *dmabuf,
> > > > + struct dma_buf_attachment
> > > > *attachment)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + struct dma_heap_attachment *a = attachment->priv;
> > > > +
> > > > + mutex_lock(&buffer->lock);
> > > > + list_del(&a->list);
> > > > + mutex_unlock(&buffer->lock);
> > > > +
> > > > + sg_free_table(a->table);
> > > > + kfree(a->table);
> > > > + kfree(a);
> > > > +}
> > > > +
> > > > +static struct sg_table *secure_heap_map_dma_buf(struct
> > > > dma_buf_attachment *attachment,
> > > > + enum
> > > > dma_data_direction direction)
> > > > +{
> > > > + struct dma_heap_attachment *a = attachment->priv;
> > > > + struct sg_table *table = a->table;
> > > > + int attr = 0;
> > > > + int ret;
> > > > +
> > > > + if (!a->no_map) {
> > >
> > > This looks strange - you're expecting this driver to be used on
> > > regions with no-map set, but if no-map _is_ set, you don't allow
> > > the
> > > dma_buf to get mapped to any devices. Doesn't that mean that
> > > these
> > > buffers can never actually be used?
> >
> > if no-map is not set, map_dma_buf is mapping the buffer.
> >
>
> no-map prevents the memory region from being added to the kernel's
> linear mapping. Irrespective of no-map, map_dma_buf is needed to map
> a buffer to a device, this should be orthogonal to no-map, and is
> definitely required for devices to be able to use these buffers.
>
> > >
> > > > + if (a->uncached)
> > > > + attr = DMA_ATTR_SKIP_CPU_SYNC;
> > > > +
> > >
> > > If the CPU can never touch these buffers, is cached vs uncached
> > > meaningful?
> >
> > indeed, but as dma_buf_ops.map_dma_buf is mandatory, this flag as
> > well
> > as no-map were introduce to manage uncached mapped buffer.
> >
>
> Uncached mapping where? I think we're agreed that these buffers can
> never be mapped for (non-trusted) CPU access, therefore (non-trusted)
> CPU cache maintenance doesn't apply. Devices may still have cached
> mappings, but it's up to device drivers to manage that.
>
> > to simplify everything, secure-heap could get rid of no-map and
> > uncached flags and set an is_protected flag in dma_buf ?
> >
>
> I think that sounds better, yeah.
>
> >
> > > If the TEE touches the buffers from the CPU then perhaps the TEE
> > > would
> > > need to do cache maintenance, but I'd expect that to be managed
> > > in
> > > the
> > > TEE.
> >
> > yes, if needed cache maintenance should be done in TA.
> >
> > >
> > > > + ret = dma_map_sgtable(attachment->dev, table,
> > > > direction, attr);
> > > > + if (ret)
> > > > + return ERR_PTR(ret);
> > > > +
> > > > + a->mapped = true;
> > > > + }
> > > > +
> > > > + return table;
> > > > +}
> > > > +
> > > > +static void secure_heap_unmap_dma_buf(struct
> > > > dma_buf_attachment
> > > > *attachment,
> > > > + struct sg_table *table,
> > > > + enum dma_data_direction
> > > > direction)
> > > > +{
> > > > + struct dma_heap_attachment *a = attachment->priv;
> > > > + int attr = 0;
> > > > +
> > > > + if (!a->no_map) {
> > > > + if (a->uncached)
> > > > + attr = DMA_ATTR_SKIP_CPU_SYNC;
> > > > +
> > > > + a->mapped = false;
> > > > + dma_unmap_sgtable(attachment->dev, table,
> > > > direction,
> > > > attr);
> > > > + }
> > > > +}
> > > > +
> > > > +static int secure_heap_dma_buf_begin_cpu_access(struct dma_buf
> > > > *dmabuf,
> > > > + enum
> > > > dma_data_direction direction)
> > >
> > > If the firewall is preventing CPU accesses, then shouldn't
> > > begin_cpu_access and end_cpu_access either fail or be a no-op?
> >
> > true, both of them are optional and could be removed.
> >
> > >
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + struct dma_heap_attachment *a;
> > > > +
> > > > + mutex_lock(&buffer->lock);
> > > > +
> > > > + if (buffer->vmap_cnt)
> > > > + invalidate_kernel_vmap_range(buffer->vaddr,
> > > > buffer-
> > > > > len);
> > > >
> > > > +
> > > > + if (!buffer->uncached) {
> > > > + list_for_each_entry(a, &buffer->attachments,
> > > > list) {
> > > > + if (!a->mapped)
> > > > + continue;
> > > > + dma_sync_sgtable_for_cpu(a->dev, a-
> > > > >table,
> > > > direction);
> > > > + }
> > > > + }
> > > > + mutex_unlock(&buffer->lock);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static int secure_heap_dma_buf_end_cpu_access(struct dma_buf
> > > > *dmabuf,
> > > > + enum
> > > > dma_data_direction
> > > > direction)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + struct dma_heap_attachment *a;
> > > > +
> > > > + mutex_lock(&buffer->lock);
> > > > +
> > > > + if (buffer->vmap_cnt)
> > > > + flush_kernel_vmap_range(buffer->vaddr, buffer-
> > > > >len);
> > > > +
> > > > + if (!buffer->uncached) {
> > > > + list_for_each_entry(a, &buffer->attachments,
> > > > list) {
> > > > + if (!a->mapped)
> > > > + continue;
> > > > + dma_sync_sgtable_for_device(a->dev, a-
> > > > >table,
> > > > direction);
> > > > + }
> > > > + }
> > > > + mutex_unlock(&buffer->lock);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static int secure_heap_mmap(struct dma_buf *dmabuf, struct
> > > > vm_area_struct *vma)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + struct sg_table *table = &buffer->sg_table;
> > > > + unsigned long addr = vma->vm_start;
> > > > + struct sg_page_iter piter;
> > > > + int ret;
> > > > +
> > > > + if (buffer->uncached)
> > > > + vma->vm_page_prot = pgprot_writecombine(vma-
> > > > > vm_page_prot);
> > > >
> > > > +
> > > > + for_each_sgtable_page(table, &piter, vma->vm_pgoff) {
> > > > + struct page *page = sg_page_iter_page(&piter);
> > > > +
> > > > + ret = remap_pfn_range(vma, addr,
> > > > page_to_pfn(page),
> > > > PAGE_SIZE,
> > > > + vma->vm_page_prot);
> > >
> > > If the CPU can't touch these buffers, what would they be mapped
> > > to
> > > userspace for?
> >
> > again, let's remove this optional ops.
> >
> > >
> > > > + if (ret)
> > > > + return ret;
> > > > + addr += PAGE_SIZE;
> > > > + }
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static void *secure_heap_do_vmap(struct secure_heap_buffer
> > > > *buffer)
> > > > +{
> > > > + struct sg_table *table = &buffer->sg_table;
> > > > + int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE;
> > > > + struct page **pages = vmalloc(sizeof(struct page *) *
> > > > npages);
> > > > + struct page **tmp = pages;
> > > > + struct sg_page_iter piter;
> > > > + pgprot_t pgprot = PAGE_KERNEL;
> > > > + void *vaddr;
> > > > +
> > > > + if (!pages)
> > > > + return ERR_PTR(-ENOMEM);
> > > > +
> > > > + if (buffer->uncached)
> > > > + pgprot = pgprot_writecombine(PAGE_KERNEL);
> > > > +
> > > > + for_each_sgtable_page(table, &piter, 0) {
> > > > + WARN_ON(tmp - pages >= npages);
> > > > + *tmp++ = sg_page_iter_page(&piter);
> > > > + }
> > > > +
> > > > + vaddr = vmap(pages, npages, VM_MAP, pgprot);
> > > > + vfree(pages);
> > >
> > > Similar to above, if the CPU can't touch these buffers, what
> > > would be
> > > the point of mapping them to the kernel?
> >
> > indeed, useless code.
> >
> > >
> > > > +
> > > > + if (!vaddr)
> > > > + return ERR_PTR(-ENOMEM);
> > > > +
> > > > + return vaddr;
> > > > +}
> > > > +
> > > > +static int secure_heap_vmap(struct dma_buf *dmabuf, struct
> > > > dma_buf_map *map)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + void *vaddr;
> > > > + int ret = 0;
> > > > +
> > > > + mutex_lock(&buffer->lock);
> > > > + if (buffer->vmap_cnt) {
> > > > + buffer->vmap_cnt++;
> > > > + goto out;
> > > > + }
> > > > +
> > > > + vaddr = secure_heap_do_vmap(buffer);
> > > > + if (IS_ERR(vaddr)) {
> > > > + ret = PTR_ERR(vaddr);
> > > > + goto out;
> > > > + }
> > > > +
> > > > + buffer->vaddr = vaddr;
> > > > + buffer->vmap_cnt++;
> > > > + dma_buf_map_set_vaddr(map, buffer->vaddr);
> > > > +out:
> > > > + mutex_unlock(&buffer->lock);
> > > > +
> > > > + return ret;
> > > > +}
> > > > +
> > > > +static void secure_heap_vunmap(struct dma_buf *dmabuf, struct
> > > > dma_buf_map *map)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > +
> > > > + mutex_lock(&buffer->lock);
> > > > + if (!--buffer->vmap_cnt) {
> > > > + vunmap(buffer->vaddr);
> > > > + buffer->vaddr = NULL;
> > > > + }
> > > > + mutex_unlock(&buffer->lock);
> > > > + dma_buf_map_clear(map);
> > > > +}
> > > > +
> > > > +static void secure_heap_zero_buffer(struct secure_heap_buffer
> > > > *buffer)
> > > > +{
> > > > + struct sg_table *sgt = &buffer->sg_table;
> > > > + struct sg_page_iter piter;
> > > > + struct page *p;
> > > > + void *vaddr;
> > > > +
> > > > + for_each_sgtable_page(sgt, &piter, 0) {
> > > > + p = sg_page_iter_page(&piter);
> > > > + vaddr = kmap_atomic(p);
> > > > + memset(vaddr, 0, PAGE_SIZE);
> > >
> > > How can you do memset on the buffer if the firewall is preventing
> > > CPU
> > > accesses?
> > >
> >
> > yes, useless if we set a secure flag to prevent driver from mapping
> > allocated buffer.
> >
>
> Wouldn't you still want the buffers to be zeroed? I think you need
> a way to ask the TEE to zero them.
>
> This also makes me wonder about the deferred free mechanism. If you
> aren't zeroing then there's no need for the deferred free, and if
> allocations are coming from a reserved-memory region then the
> shrinker
> mechanism doesn't make sense because freeing up the deferred buffers
> won't help relieve memory pressure.
>
> I wonder if it would be better to have a more specialised deferred
> free mechanism as part of this heap (if necessary), rather than
> library-ise it as you have in patch 1.
>
> > > > + kunmap_atomic(vaddr);
> > > > + }
> > > > +}
> > > > +
> > > > +static void secure_heap_buf_free(struct deferred_freelist_item
> > > > *item,
> > > > + enum df_reason reason)
> > > > +{
> > > > + struct secure_heap_buffer *buffer;
> > > > + struct secure_heap_info *info;
> > > > + struct sg_table *table;
> > > > + struct scatterlist *sg;
> > > > + int i;
> > > > +
> > > > + buffer = container_of(item, struct secure_heap_buffer,
> > > > deferred_free);
> > > > + info = dma_heap_get_drvdata(buffer->heap);
> > > > +
> > > > + if (!info->no_map) {
> > > > + // Zero the buffer pages before adding back to
> > > > the
> > > > pool
> > > > + if (reason == DF_NORMAL)
> > > > + secure_heap_zero_buffer(buffer);
> > > > + }
> > > > +
> > > > + table = &buffer->sg_table;
> > > > + for_each_sg(table->sgl, sg, table->nents, i)
> > > > + gen_pool_free(info->pool, sg_dma_address(sg),
> > > > sg_dma_len(sg));
> > > > +
> > > > + sg_free_table(table);
> > > > + kfree(buffer);
> > > > +}
> > > > +
> > > > +static void secure_heap_dma_buf_release(struct dma_buf
> > > > *dmabuf)
> > > > +{
> > > > + struct secure_heap_buffer *buffer = dmabuf->priv;
> > > > + int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE;
> > > > +
> > > > + deferred_free(&buffer->deferred_free,
> > > > secure_heap_buf_free,
> > > > npages);
> > > > +}
> > > > +
> > > > +static const struct dma_buf_ops secure_heap_buf_ops = {
> > > > + .attach = secure_heap_attach,
> > > > + .detach = secure_heap_detach,
> > > > + .map_dma_buf = secure_heap_map_dma_buf,
> > > > + .unmap_dma_buf = secure_heap_unmap_dma_buf,
> > > > + .begin_cpu_access = secure_heap_dma_buf_begin_cpu_access,
> > > > + .end_cpu_access = secure_heap_dma_buf_end_cpu_access,
> > > > + .mmap = secure_heap_mmap,
> > > > + .vmap = secure_heap_vmap,
> > > > + .vunmap = secure_heap_vunmap,
> > > > + .release = secure_heap_dma_buf_release,
> > > > +};
> > > > +
> > > > +static struct dma_buf *secure_heap_do_allocate(struct dma_heap
> > > > *heap,
> > > > + unsigned long len,
> > > > + unsigned long
> > > > fd_flags,
> > > > + unsigned long
> > > > heap_flags,
> > > > + bool uncached)
> > > > +{
> > > > + struct secure_heap_buffer *buffer;
> > > > + struct secure_heap_info *info =
> > > > dma_heap_get_drvdata(heap);
> > > > + DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> > > > + unsigned long size = roundup(len, PAGE_SIZE);
> > > > + struct dma_buf *dmabuf;
> > > > + struct sg_table *table;
> > > > + int ret = -ENOMEM;
> > > > + unsigned long phy_addr;
> > > > +
> > > > + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
> > > > + if (!buffer)
> > > > + return ERR_PTR(-ENOMEM);
> > > > +
> > > > + INIT_LIST_HEAD(&buffer->attachments);
> > > > + mutex_init(&buffer->lock);
> > > > + buffer->heap = heap;
> > > > + buffer->len = size;
> > > > + buffer->uncached = uncached;
> > > > +
> > > > + phy_addr = gen_pool_alloc(info->pool, size);
> > > > + if (!phy_addr)
> > > > + goto free_buffer;
> > > > +
> > > > + table = &buffer->sg_table;
> > > > + if (sg_alloc_table(table, 1, GFP_KERNEL))
> > > > + goto free_pool;
> > > > +
> > > > + sg_set_page(table->sgl, phys_to_page(phy_addr), size, 0);
> > > > + sg_dma_address(table->sgl) = phy_addr;
> > > > + sg_dma_len(table->sgl) = size;
> > > > +
> > > > + /* create the dmabuf */
> > > > + exp_info.exp_name = dma_heap_get_name(heap);
> > > > + exp_info.ops = &secure_heap_buf_ops;
> > > > + exp_info.size = buffer->len;
> > > > + exp_info.flags = fd_flags;
> > > > + exp_info.priv = buffer;
> > > > + dmabuf = dma_buf_export(&exp_info);
> > > > + if (IS_ERR(dmabuf)) {
> > > > + ret = PTR_ERR(dmabuf);
> > > > + goto free_pages;
> > > > + }
> > > > +
> > > > + return dmabuf;
> > > > +
> > > > +free_pages:
> > > > + sg_free_table(table);
> > > > +
> > > > +free_pool:
> > > > + gen_pool_free(info->pool, phy_addr, size);
> > > > +
> > > > +free_buffer:
> > > > + mutex_destroy(&buffer->lock);
> > > > + kfree(buffer);
> > > > +
> > > > + return ERR_PTR(ret);
> > > > +}
> > > > +
> > > > +static struct dma_buf *secure_heap_allocate(struct dma_heap
> > > > *heap,
> > > > + unsigned long len,
> > > > + unsigned long
> > > > fd_flags,
> > > > + unsigned long
> > > > heap_flags)
> > > > +{
> > > > + // use uncache buffer here by default
> > > > + return secure_heap_do_allocate(heap, len, fd_flags,
> > > > heap_flags, true);
> > > > + // use cache buffer
> > > > + // return secure_heap_do_allocate(heap, len, fd_flags,
> > > > heap_flags, false);
> > > > +}
> > > > +
> > > > +static const struct dma_heap_ops secure_heap_ops = {
> > > > + .allocate = secure_heap_allocate,
> > > > +};
> > > > +
> > > > +static int secure_heap_add(struct rmem_secure *rmem)
> > > > +{
> > > > + struct dma_heap *secure_heap;
> > > > + struct dma_heap_export_info exp_info;
> > > > + struct secure_heap_info *info = NULL;
> > > > + struct gen_pool *pool = NULL;
> > > > + int ret = -EINVAL;
> > > > +
> > > > + if (rmem->base == 0 || rmem->size == 0) {
> > > > + pr_err("secure_data base or size is not
> > > > correct\n");
> > > > + goto error;
> > > > + }
> > > > +
> > > > + info = kzalloc(sizeof(*info), GFP_KERNEL);
> > > > + if (!info) {
> > > > + pr_err("dmabuf info allocation failed\n");
> > > > + ret = -ENOMEM;
> > > > + goto error;
> > > > + }
> > > > +
> > > > + pool = gen_pool_create(PAGE_SHIFT, -1);
> > > > + if (!pool) {
> > > > + pr_err("can't create gen pool\n");
> > > > + ret = -ENOMEM;
> > > > + goto error;
> > > > + }
> > > > +
> > > > + if (gen_pool_add(pool, rmem->base, rmem->size, -1) < 0) {
> > > > + pr_err("failed to add memory into pool\n");
> > > > + ret = -ENOMEM;
> > > > + goto error;
> > > > + }
> > > > +
> > > > + info->pool = pool;
> > > > + info->no_map = rmem->no_map;
> > >
> > > This kind of heap probably can't work if the region doesn't have
> > > no-map, so I think it would make sense to enforce that no_map is
> > > set
> > > (or ignore regions without no-map in DT).
> >
> > if no-map is not set, secure-heap could be used as a heap with
> > dynamically protected buffer from the TEE.
>
> That would need a whole bunch more code to call in to the TEE to
> apply
> the protection. So hypothetically yes, that's true, but not without
> more code than what you have here.
>
> > but I agree that this is adding too much complexity and could be
> > simplify a lot without this mapping consideration.
> >
> > then no-map is probably not the perfect term to describe this heap.
> > is_s
> > ecure or is_protected would be better ?
>
> You mean in device-tree? no-map has a well-defined meaning; and if
> this memory region shouldn't be added to the kernel's linear map
> then it should be tagged with no-map.
>
> Whether there should also be some DT property indicating that the
> region is protected and can't be accessed normally: I don't have
> much of an opinion on that.
>
> Thanks,
> -Brian
>
> >
> > >
> > > Cheers,
> > > -Brian
> > >
> > > > +
> > > > + exp_info.name = rmem->name;
> > > > + exp_info.ops = &secure_heap_ops;
> > > > + exp_info.priv = info;
> > > > +
> > > > + secure_heap = dma_heap_add(&exp_info);
> > > > + if (IS_ERR(secure_heap)) {
> > > > + pr_err("dmabuf secure heap allocation failed\n");
> > > > + ret = PTR_ERR(secure_heap);
> > > > + goto error;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +
> > > > +error:
> > > > + kfree(info);
> > > > + if (pool)
> > > > + gen_pool_destroy(pool);
> > > > +
> > > > + return ret;
> > > > +}
> > > > +
> > > > +static int secure_heap_create(void)
> > > > +{
> > > > + unsigned int i;
> > > > + int ret;
> > > > +
> > > > + for (i = 0; i < secure_data_count; i++) {
> > > > + ret = secure_heap_add(&secure_data[i]);
> > > > + if (ret)
> > > > + return ret;
> > > > + }
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static int rmem_secure_heap_device_init(struct reserved_mem
> > > > *rmem,
> > > > + struct device *dev)
> > > > +{
> > > > + dev_set_drvdata(dev, rmem);
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static void rmem_secure_heap_device_release(struct
> > > > reserved_mem
> > > > *rmem,
> > > > + struct device *dev)
> > > > +{
> > > > + dev_set_drvdata(dev, NULL);
> > > > +}
> > > > +
> > > > +static const struct reserved_mem_ops rmem_dma_ops = {
> > > > + .device_init = rmem_secure_heap_device_init,
> > > > + .device_release = rmem_secure_heap_device_release,
> > > > +};
> > > > +
> > > > +static int __init rmem_secure_heap_setup(struct reserved_mem
> > > > *rmem)
> > > > +{
> > > > + if (secure_data_count < MAX_SECURE_HEAP) {
> > > > + int name_len = 0;
> > > > + char *s = rmem->name;
> > > > +
> > > > + secure_data[secure_data_count].base = rmem->base;
> > > > + secure_data[secure_data_count].size = rmem->size;
> > > > + secure_data[secure_data_count].no_map =
> > > > + (of_get_flat_dt_prop(rmem->fdt_node, "no-
> > > > map", NULL) != NULL);
> > > > +
> > > > + while (name_len < MAX_HEAP_NAME_LEN) {
> > > > + if ((*s == '@') || (*s == '\0'))
> > > > + break;
> > > > + name_len++;
> > > > + s++;
> > > > + }
> > > > + if (name_len == MAX_HEAP_NAME_LEN)
> > > > + name_len--;
> > > > +
> > > > + strncpy(secure_data[secure_data_count].name,
> > > > rmem-
> > > > > name, name_len);
> > > >
> > > > +
> > > > + rmem->ops = &rmem_dma_ops;
> > > > + pr_info("Reserved memory: DMA buf secure pool %s
> > > > at
> > > > %pa, size %ld MiB\n",
> > > > + secure_data[secure_data_count].name,
> > > > + &rmem->base, (unsigned long)rmem->size /
> > > > SZ_1M);
> > > > +
> > > > + secure_data_count++;
> > > > + return 0;
> > > > + }
> > > > + WARN_ONCE(1, "Cannot handle more than %u secure heaps\n",
> > > > MAX_SECURE_HEAP);
> > > > + return -EINVAL;
> > > > +}
> > > > +
> > > > +RESERVEDMEM_OF_DECLARE(secure_heap, "linaro,secure-heap",
> > > > rmem_secure_heap_setup);
> > > > +
> > > > +module_init(secure_heap_create);
> > > > +MODULE_LICENSE("GPL v2");
> > > > --
> > > > 2.25.0
> > > >
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