| Message ID | 20200923123205.30671-2-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | dma-buf: Flag vmap'ed memory as system or I/O memory | expand |
Am 23.09.20 um 14:32 schrieb Thomas Zimmermann: > The new type struct dma_buf_map represents a mapping of dma-buf memory > into kernel space. It contains a flag, is_iomem, that signals users to > access the mapped memory with I/O operations instead of regular loads > and stores. > > It was assumed that DMA buffer memory can be accessed with regular load > and store operations. Some architectures, such as sparc64, require the > use of I/O operations to access dma-map buffers that are located in I/O > memory. Providing struct dma_buf_map allows drivers to implement this. > This was specifically a problem when refreshing the graphics framebuffer > on such systems. [1] > > As the first step, struct dma_buf stores an instance of struct dma_buf_map > internally. Afterwards, dma-buf's vmap and vunmap interfaces are be > converted. Finally, affected drivers can be fixed. > > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fdri-devel%2F20200725191012.GA434957%40ravnborg.org%2F&data=02%7C01%7Cchristian.koenig%40amd.com%7C54486b9682654f3950b808d85fbcb1d3%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637364611338153209&sdata=%2BZm7t8OcgkIxnY%2FdZSLhSbKC7t1y4VW5lINFKwCQv3A%3D&reserved=0 Only two nit picks below, apart from that Reviewed-by: Christian König <christian.koenig@amd.com> > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > Acked-by: Sumit Semwal <sumit.semwal@linaro.org> > --- > Documentation/driver-api/dma-buf.rst | 3 + > drivers/dma-buf/dma-buf.c | 14 ++--- > include/linux/dma-buf-map.h | 87 ++++++++++++++++++++++++++++ > include/linux/dma-buf.h | 3 +- > 4 files changed, 99 insertions(+), 8 deletions(-) > create mode 100644 include/linux/dma-buf-map.h > > diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst > index 13ea0cc0a3fa..3244c600a9a1 100644 > --- a/Documentation/driver-api/dma-buf.rst > +++ b/Documentation/driver-api/dma-buf.rst > @@ -115,6 +115,9 @@ Kernel Functions and Structures Reference > .. kernel-doc:: include/linux/dma-buf.h > :internal: > > +.. kernel-doc:: include/linux/dma-buf-map.h > + :internal: > + > Reservation Objects > ------------------- > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 58564d82a3a2..5e849ca241a0 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -1207,12 +1207,12 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) > mutex_lock(&dmabuf->lock); > if (dmabuf->vmapping_counter) { > dmabuf->vmapping_counter++; > - BUG_ON(!dmabuf->vmap_ptr); > - ptr = dmabuf->vmap_ptr; > + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); > + ptr = dmabuf->vmap_ptr.vaddr; > goto out_unlock; > } > > - BUG_ON(dmabuf->vmap_ptr); > + BUG_ON(dma_buf_map_is_set(&dmabuf->vmap_ptr)); > > ptr = dmabuf->ops->vmap(dmabuf); > if (WARN_ON_ONCE(IS_ERR(ptr))) > @@ -1220,7 +1220,7 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) > if (!ptr) > goto out_unlock; > > - dmabuf->vmap_ptr = ptr; > + dmabuf->vmap_ptr.vaddr = ptr; > dmabuf->vmapping_counter = 1; > > out_unlock: > @@ -1239,15 +1239,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) > if (WARN_ON(!dmabuf)) > return; > > - BUG_ON(!dmabuf->vmap_ptr); > + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); > BUG_ON(dmabuf->vmapping_counter == 0); > - BUG_ON(dmabuf->vmap_ptr != vaddr); > + BUG_ON(!dma_buf_map_is_vaddr(&dmabuf->vmap_ptr, vaddr)); > > mutex_lock(&dmabuf->lock); > if (--dmabuf->vmapping_counter == 0) { > if (dmabuf->ops->vunmap) > dmabuf->ops->vunmap(dmabuf, vaddr); > - dmabuf->vmap_ptr = NULL; > + dma_buf_map_clear(&dmabuf->vmap_ptr); > } > mutex_unlock(&dmabuf->lock); > } > diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h > new file mode 100644 > index 000000000000..d4b1bb3cc4b0 > --- /dev/null > +++ b/include/linux/dma-buf-map.h > @@ -0,0 +1,87 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Pointer to dma-buf-mapped memory, plus helpers. > + */ > + > +#ifndef __DMA_BUF_MAP_H__ > +#define __DMA_BUF_MAP_H__ > + > +#include <linux/io.h> > + > +/** > + * struct dma_buf_map - Pointer to vmap'ed dma-buf memory. > + * @vaddr_iomem: The buffer's address if in I/O memory > + * @vaddr: The buffer's address if in system memory > + * @is_iomem: True if the dma-buf memory is located in I/O > + * memory, or false otherwise. > + * > + * Calling dma-buf's vmap operation returns a pointer to the buffer. > + * Depending on the location of the buffer, users may have to access it > + * with I/O operations or memory load/store operations. struct dma_buf_map > + * stores the buffer address and a flag that signals the required access. > + */ > +struct dma_buf_map { > + union { > + void __iomem *vaddr_iomem; > + void *vaddr; > + }; > + bool is_iomem; > +}; > + > +/* API transition helper */ > +static inline bool dma_buf_map_is_vaddr(const struct dma_buf_map *map, const void *vaddr) > +{ > + return !map->is_iomem && (map->vaddr == vaddr); > +} > + > +/** > + * dma_buf_map_is_null - Tests for a dma-buf mapping to be NULL > + * @map: The dma-buf mapping structure > + * > + * Depending on the state of struct dma_buf_map.is_iomem, tests if the > + * mapping is NULL. > + * > + * Returns: > + * True if the mapping is NULL, or false otherwise. > + */ > +static inline bool dma_buf_map_is_null(const struct dma_buf_map *map) > +{ > + if (map->is_iomem) > + return map->vaddr_iomem == NULL; > + return map->vaddr == NULL; This looks like overkill since both pointers are part of the same union. I suggest to test only one and add a comment. > +} > + > +/** > + * dma_buf_map_is_set - Tests is the dma-buf mapping has been set > + * @map: The dma-buf mapping structure > + * > + * Depending on the state of struct dma_buf_map.is_iomem, tests if the > + * mapping has been set. > + * > + * Returns: > + * True if the mapping is been set, or false otherwise. > + */ > +static inline bool dma_buf_map_is_set(const struct dma_buf_map *map) > +{ > + return !dma_buf_map_is_null(map); > +} > + > +/** > + * dma_buf_map_clear - Clears a dma-buf mapping structure > + * @map: The dma-buf mapping structure > + * > + * Clears all fields to zero; including struct dma_buf_map.is_iomem. So > + * mapping structures that were set to point to I/O memory are reset for > + * system memory. Pointers are cleared to NULL. This is the default. > + */ > +static inline void dma_buf_map_clear(struct dma_buf_map *map) > +{ > + if (map->is_iomem) { > + map->vaddr_iomem = NULL; > + map->is_iomem = false; > + } else { > + map->vaddr = NULL; > + } Maybe just use memset() on the structure. Christian. > +} > + > +#endif /* __DMA_BUF_MAP_H__ */ > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index 957b398d30e5..fcc2ddfb6d18 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -13,6 +13,7 @@ > #ifndef __DMA_BUF_H__ > #define __DMA_BUF_H__ > > +#include <linux/dma-buf-map.h> > #include <linux/file.h> > #include <linux/err.h> > #include <linux/scatterlist.h> > @@ -309,7 +310,7 @@ struct dma_buf { > const struct dma_buf_ops *ops; > struct mutex lock; > unsigned vmapping_counter; > - void *vmap_ptr; > + struct dma_buf_map vmap_ptr; > const char *exp_name; > const char *name; > spinlock_t name_lock;
On Wed, Sep 23, 2020 at 04:27:04PM +0200, Christian König wrote: > Am 23.09.20 um 14:32 schrieb Thomas Zimmermann: > > The new type struct dma_buf_map represents a mapping of dma-buf memory > > into kernel space. It contains a flag, is_iomem, that signals users to > > access the mapped memory with I/O operations instead of regular loads > > and stores. > > > > It was assumed that DMA buffer memory can be accessed with regular load > > and store operations. Some architectures, such as sparc64, require the > > use of I/O operations to access dma-map buffers that are located in I/O > > memory. Providing struct dma_buf_map allows drivers to implement this. > > This was specifically a problem when refreshing the graphics framebuffer > > on such systems. [1] > > > > As the first step, struct dma_buf stores an instance of struct dma_buf_map > > internally. Afterwards, dma-buf's vmap and vunmap interfaces are be > > converted. Finally, affected drivers can be fixed. > > > > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fdri-devel%2F20200725191012.GA434957%40ravnborg.org%2F&data=02%7C01%7Cchristian.koenig%40amd.com%7C54486b9682654f3950b808d85fbcb1d3%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637364611338153209&sdata=%2BZm7t8OcgkIxnY%2FdZSLhSbKC7t1y4VW5lINFKwCQv3A%3D&reserved=0 > > Only two nit picks below, apart from that Reviewed-by: Christian König > <christian.koenig@amd.com> > > > > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > > Acked-by: Sumit Semwal <sumit.semwal@linaro.org> > > --- > > Documentation/driver-api/dma-buf.rst | 3 + > > drivers/dma-buf/dma-buf.c | 14 ++--- > > include/linux/dma-buf-map.h | 87 ++++++++++++++++++++++++++++ > > include/linux/dma-buf.h | 3 +- > > 4 files changed, 99 insertions(+), 8 deletions(-) > > create mode 100644 include/linux/dma-buf-map.h > > > > diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst > > index 13ea0cc0a3fa..3244c600a9a1 100644 > > --- a/Documentation/driver-api/dma-buf.rst > > +++ b/Documentation/driver-api/dma-buf.rst > > @@ -115,6 +115,9 @@ Kernel Functions and Structures Reference > > .. kernel-doc:: include/linux/dma-buf.h > > :internal: Please add a heading here, maybe "Buffer mapping helpers" or somethig like that. > > +.. kernel-doc:: include/linux/dma-buf-map.h > > + :internal: > > + > > Reservation Objects > > ------------------- > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > > index 58564d82a3a2..5e849ca241a0 100644 > > --- a/drivers/dma-buf/dma-buf.c > > +++ b/drivers/dma-buf/dma-buf.c > > @@ -1207,12 +1207,12 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) > > mutex_lock(&dmabuf->lock); > > if (dmabuf->vmapping_counter) { > > dmabuf->vmapping_counter++; > > - BUG_ON(!dmabuf->vmap_ptr); > > - ptr = dmabuf->vmap_ptr; > > + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); > > + ptr = dmabuf->vmap_ptr.vaddr; > > goto out_unlock; > > } > > - BUG_ON(dmabuf->vmap_ptr); > > + BUG_ON(dma_buf_map_is_set(&dmabuf->vmap_ptr)); > > ptr = dmabuf->ops->vmap(dmabuf); > > if (WARN_ON_ONCE(IS_ERR(ptr))) > > @@ -1220,7 +1220,7 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) > > if (!ptr) > > goto out_unlock; > > - dmabuf->vmap_ptr = ptr; > > + dmabuf->vmap_ptr.vaddr = ptr; > > dmabuf->vmapping_counter = 1; > > out_unlock: > > @@ -1239,15 +1239,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) > > if (WARN_ON(!dmabuf)) > > return; > > - BUG_ON(!dmabuf->vmap_ptr); > > + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); > > BUG_ON(dmabuf->vmapping_counter == 0); > > - BUG_ON(dmabuf->vmap_ptr != vaddr); > > + BUG_ON(!dma_buf_map_is_vaddr(&dmabuf->vmap_ptr, vaddr)); > > mutex_lock(&dmabuf->lock); > > if (--dmabuf->vmapping_counter == 0) { > > if (dmabuf->ops->vunmap) > > dmabuf->ops->vunmap(dmabuf, vaddr); > > - dmabuf->vmap_ptr = NULL; > > + dma_buf_map_clear(&dmabuf->vmap_ptr); > > } > > mutex_unlock(&dmabuf->lock); > > } > > diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h > > new file mode 100644 > > index 000000000000..d4b1bb3cc4b0 > > --- /dev/null > > +++ b/include/linux/dma-buf-map.h > > @@ -0,0 +1,87 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* > > + * Pointer to dma-buf-mapped memory, plus helpers. > > + */ > > + > > +#ifndef __DMA_BUF_MAP_H__ > > +#define __DMA_BUF_MAP_H__ > > + > > +#include <linux/io.h> > > + > > +/** > > + * struct dma_buf_map - Pointer to vmap'ed dma-buf memory. > > + * @vaddr_iomem: The buffer's address if in I/O memory > > + * @vaddr: The buffer's address if in system memory > > + * @is_iomem: True if the dma-buf memory is located in I/O > > + * memory, or false otherwise. > > + * > > + * Calling dma-buf's vmap operation returns a pointer to the buffer. > > + * Depending on the location of the buffer, users may have to access it > > + * with I/O operations or memory load/store operations. struct dma_buf_map > > + * stores the buffer address and a flag that signals the required access. Maybe explain that this can be used in general for abstracting away the difference between system memory and __iomem for buffer mappings. Or something like that - it's not exlusively tied to dma-buf, just a convenient place. > > + */ > > +struct dma_buf_map { > > + union { > > + void __iomem *vaddr_iomem; > > + void *vaddr; > > + }; > > + bool is_iomem; > > +}; > > + > > +/* API transition helper */ > > +static inline bool dma_buf_map_is_vaddr(const struct dma_buf_map *map, const void *vaddr) > > +{ > > + return !map->is_iomem && (map->vaddr == vaddr); > > +} > > + > > +/** > > + * dma_buf_map_is_null - Tests for a dma-buf mapping to be NULL > > + * @map: The dma-buf mapping structure > > + * > > + * Depending on the state of struct dma_buf_map.is_iomem, tests if the > > + * mapping is NULL. > > + * > > + * Returns: > > + * True if the mapping is NULL, or false otherwise. > > + */ > > +static inline bool dma_buf_map_is_null(const struct dma_buf_map *map) > > +{ > > + if (map->is_iomem) > > + return map->vaddr_iomem == NULL; > > + return map->vaddr == NULL; > > This looks like overkill since both pointers are part of the same union. > > I suggest to test only one and add a comment. > > > +} > > + > > +/** > > + * dma_buf_map_is_set - Tests is the dma-buf mapping has been set > > + * @map: The dma-buf mapping structure > > + * > > + * Depending on the state of struct dma_buf_map.is_iomem, tests if the > > + * mapping has been set. > > + * > > + * Returns: > > + * True if the mapping is been set, or false otherwise. > > + */ > > +static inline bool dma_buf_map_is_set(const struct dma_buf_map *map) > > +{ > > + return !dma_buf_map_is_null(map); > > +} > > + > > +/** > > + * dma_buf_map_clear - Clears a dma-buf mapping structure > > + * @map: The dma-buf mapping structure > > + * > > + * Clears all fields to zero; including struct dma_buf_map.is_iomem. So > > + * mapping structures that were set to point to I/O memory are reset for > > + * system memory. Pointers are cleared to NULL. This is the default. > > + */ > > +static inline void dma_buf_map_clear(struct dma_buf_map *map) > > +{ > > + if (map->is_iomem) { > > + map->vaddr_iomem = NULL; > > + map->is_iomem = false; > > + } else { > > + map->vaddr = NULL; > > + } > > Maybe just use memset() on the structure. gcc should be able to see through this, and I think the clever code is maybe a bit too clever. I'd leave it as-is. Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > Christian. > > > +} > > + > > +#endif /* __DMA_BUF_MAP_H__ */ > > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > > index 957b398d30e5..fcc2ddfb6d18 100644 > > --- a/include/linux/dma-buf.h > > +++ b/include/linux/dma-buf.h > > @@ -13,6 +13,7 @@ > > #ifndef __DMA_BUF_H__ > > #define __DMA_BUF_H__ > > +#include <linux/dma-buf-map.h> > > #include <linux/file.h> > > #include <linux/err.h> > > #include <linux/scatterlist.h> > > @@ -309,7 +310,7 @@ struct dma_buf { > > const struct dma_buf_ops *ops; > > struct mutex lock; > > unsigned vmapping_counter; > > - void *vmap_ptr; > > + struct dma_buf_map vmap_ptr; > > const char *exp_name; > > const char *name; > > spinlock_t name_lock; >
Hi Am 23.09.20 um 16:27 schrieb Christian König: > Am 23.09.20 um 14:32 schrieb Thomas Zimmermann: >> The new type struct dma_buf_map represents a mapping of dma-buf memory >> into kernel space. It contains a flag, is_iomem, that signals users to >> access the mapped memory with I/O operations instead of regular loads >> and stores. >> >> It was assumed that DMA buffer memory can be accessed with regular load >> and store operations. Some architectures, such as sparc64, require the >> use of I/O operations to access dma-map buffers that are located in I/O >> memory. Providing struct dma_buf_map allows drivers to implement this. >> This was specifically a problem when refreshing the graphics framebuffer >> on such systems. [1] >> >> As the first step, struct dma_buf stores an instance of struct >> dma_buf_map >> internally. Afterwards, dma-buf's vmap and vunmap interfaces are be >> converted. Finally, affected drivers can be fixed. >> >> [1] >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fdri-devel%2F20200725191012.GA434957%40ravnborg.org%2F&data=02%7C01%7Cchristian.koenig%40amd.com%7C54486b9682654f3950b808d85fbcb1d3%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637364611338153209&sdata=%2BZm7t8OcgkIxnY%2FdZSLhSbKC7t1y4VW5lINFKwCQv3A%3D&reserved=0 >> > > Only two nit picks below, apart from that Reviewed-by: Christian König > <christian.koenig@amd.com> > >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> >> --- >> Documentation/driver-api/dma-buf.rst | 3 + >> drivers/dma-buf/dma-buf.c | 14 ++--- >> include/linux/dma-buf-map.h | 87 ++++++++++++++++++++++++++++ >> include/linux/dma-buf.h | 3 +- >> 4 files changed, 99 insertions(+), 8 deletions(-) >> create mode 100644 include/linux/dma-buf-map.h >> >> diff --git a/Documentation/driver-api/dma-buf.rst >> b/Documentation/driver-api/dma-buf.rst >> index 13ea0cc0a3fa..3244c600a9a1 100644 >> --- a/Documentation/driver-api/dma-buf.rst >> +++ b/Documentation/driver-api/dma-buf.rst >> @@ -115,6 +115,9 @@ Kernel Functions and Structures Reference >> .. kernel-doc:: include/linux/dma-buf.h >> :internal: >> +.. kernel-doc:: include/linux/dma-buf-map.h >> + :internal: >> + >> Reservation Objects >> ------------------- >> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c >> index 58564d82a3a2..5e849ca241a0 100644 >> --- a/drivers/dma-buf/dma-buf.c >> +++ b/drivers/dma-buf/dma-buf.c >> @@ -1207,12 +1207,12 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) >> mutex_lock(&dmabuf->lock); >> if (dmabuf->vmapping_counter) { >> dmabuf->vmapping_counter++; >> - BUG_ON(!dmabuf->vmap_ptr); >> - ptr = dmabuf->vmap_ptr; >> + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); >> + ptr = dmabuf->vmap_ptr.vaddr; >> goto out_unlock; >> } >> - BUG_ON(dmabuf->vmap_ptr); >> + BUG_ON(dma_buf_map_is_set(&dmabuf->vmap_ptr)); >> ptr = dmabuf->ops->vmap(dmabuf); >> if (WARN_ON_ONCE(IS_ERR(ptr))) >> @@ -1220,7 +1220,7 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) >> if (!ptr) >> goto out_unlock; >> - dmabuf->vmap_ptr = ptr; >> + dmabuf->vmap_ptr.vaddr = ptr; >> dmabuf->vmapping_counter = 1; >> out_unlock: >> @@ -1239,15 +1239,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, >> void *vaddr) >> if (WARN_ON(!dmabuf)) >> return; >> - BUG_ON(!dmabuf->vmap_ptr); >> + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); >> BUG_ON(dmabuf->vmapping_counter == 0); >> - BUG_ON(dmabuf->vmap_ptr != vaddr); >> + BUG_ON(!dma_buf_map_is_vaddr(&dmabuf->vmap_ptr, vaddr)); >> mutex_lock(&dmabuf->lock); >> if (--dmabuf->vmapping_counter == 0) { >> if (dmabuf->ops->vunmap) >> dmabuf->ops->vunmap(dmabuf, vaddr); >> - dmabuf->vmap_ptr = NULL; >> + dma_buf_map_clear(&dmabuf->vmap_ptr); >> } >> mutex_unlock(&dmabuf->lock); >> } >> diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h >> new file mode 100644 >> index 000000000000..d4b1bb3cc4b0 >> --- /dev/null >> +++ b/include/linux/dma-buf-map.h >> @@ -0,0 +1,87 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> +/* >> + * Pointer to dma-buf-mapped memory, plus helpers. >> + */ >> + >> +#ifndef __DMA_BUF_MAP_H__ >> +#define __DMA_BUF_MAP_H__ >> + >> +#include <linux/io.h> >> + >> +/** >> + * struct dma_buf_map - Pointer to vmap'ed dma-buf memory. >> + * @vaddr_iomem: The buffer's address if in I/O memory >> + * @vaddr: The buffer's address if in system memory >> + * @is_iomem: True if the dma-buf memory is located in I/O >> + * memory, or false otherwise. >> + * >> + * Calling dma-buf's vmap operation returns a pointer to the buffer. >> + * Depending on the location of the buffer, users may have to access it >> + * with I/O operations or memory load/store operations. struct >> dma_buf_map >> + * stores the buffer address and a flag that signals the required >> access. >> + */ >> +struct dma_buf_map { >> + union { >> + void __iomem *vaddr_iomem; >> + void *vaddr; >> + }; >> + bool is_iomem; >> +}; >> + >> +/* API transition helper */ >> +static inline bool dma_buf_map_is_vaddr(const struct dma_buf_map >> *map, const void *vaddr) >> +{ >> + return !map->is_iomem && (map->vaddr == vaddr); >> +} >> + >> +/** >> + * dma_buf_map_is_null - Tests for a dma-buf mapping to be NULL >> + * @map: The dma-buf mapping structure >> + * >> + * Depending on the state of struct dma_buf_map.is_iomem, tests if the >> + * mapping is NULL. >> + * >> + * Returns: >> + * True if the mapping is NULL, or false otherwise. >> + */ >> +static inline bool dma_buf_map_is_null(const struct dma_buf_map *map) >> +{ >> + if (map->is_iomem) >> + return map->vaddr_iomem == NULL; >> + return map->vaddr == NULL; > > This looks like overkill since both pointers are part of the same union. > > I suggest to test only one and add a comment. I've been trying to separate I/O and system memory as much as possible. I'd rather leave it as it is. Best regards Thomas > >> +} >> + >> +/** >> + * dma_buf_map_is_set - Tests is the dma-buf mapping has been set >> + * @map: The dma-buf mapping structure >> + * >> + * Depending on the state of struct dma_buf_map.is_iomem, tests if the >> + * mapping has been set. >> + * >> + * Returns: >> + * True if the mapping is been set, or false otherwise. >> + */ >> +static inline bool dma_buf_map_is_set(const struct dma_buf_map *map) >> +{ >> + return !dma_buf_map_is_null(map); >> +} >> + >> +/** >> + * dma_buf_map_clear - Clears a dma-buf mapping structure >> + * @map: The dma-buf mapping structure >> + * >> + * Clears all fields to zero; including struct dma_buf_map.is_iomem. So >> + * mapping structures that were set to point to I/O memory are reset for >> + * system memory. Pointers are cleared to NULL. This is the default. >> + */ >> +static inline void dma_buf_map_clear(struct dma_buf_map *map) >> +{ >> + if (map->is_iomem) { >> + map->vaddr_iomem = NULL; >> + map->is_iomem = false; >> + } else { >> + map->vaddr = NULL; >> + } > > Maybe just use memset() on the structure. > > Christian. > >> +} >> + >> +#endif /* __DMA_BUF_MAP_H__ */ >> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h >> index 957b398d30e5..fcc2ddfb6d18 100644 >> --- a/include/linux/dma-buf.h >> +++ b/include/linux/dma-buf.h >> @@ -13,6 +13,7 @@ >> #ifndef __DMA_BUF_H__ >> #define __DMA_BUF_H__ >> +#include <linux/dma-buf-map.h> >> #include <linux/file.h> >> #include <linux/err.h> >> #include <linux/scatterlist.h> >> @@ -309,7 +310,7 @@ struct dma_buf { >> const struct dma_buf_ops *ops; >> struct mutex lock; >> unsigned vmapping_counter; >> - void *vmap_ptr; >> + struct dma_buf_map vmap_ptr; >> const char *exp_name; >> const char *name; >> spinlock_t name_lock; >
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index 13ea0cc0a3fa..3244c600a9a1 100644 --- a/Documentation/driver-api/dma-buf.rst +++ b/Documentation/driver-api/dma-buf.rst @@ -115,6 +115,9 @@ Kernel Functions and Structures Reference .. kernel-doc:: include/linux/dma-buf.h :internal: +.. kernel-doc:: include/linux/dma-buf-map.h + :internal: + Reservation Objects ------------------- diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 58564d82a3a2..5e849ca241a0 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1207,12 +1207,12 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) mutex_lock(&dmabuf->lock); if (dmabuf->vmapping_counter) { dmabuf->vmapping_counter++; - BUG_ON(!dmabuf->vmap_ptr); - ptr = dmabuf->vmap_ptr; + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); + ptr = dmabuf->vmap_ptr.vaddr; goto out_unlock; } - BUG_ON(dmabuf->vmap_ptr); + BUG_ON(dma_buf_map_is_set(&dmabuf->vmap_ptr)); ptr = dmabuf->ops->vmap(dmabuf); if (WARN_ON_ONCE(IS_ERR(ptr))) @@ -1220,7 +1220,7 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) if (!ptr) goto out_unlock; - dmabuf->vmap_ptr = ptr; + dmabuf->vmap_ptr.vaddr = ptr; dmabuf->vmapping_counter = 1; out_unlock: @@ -1239,15 +1239,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) if (WARN_ON(!dmabuf)) return; - BUG_ON(!dmabuf->vmap_ptr); + BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr)); BUG_ON(dmabuf->vmapping_counter == 0); - BUG_ON(dmabuf->vmap_ptr != vaddr); + BUG_ON(!dma_buf_map_is_vaddr(&dmabuf->vmap_ptr, vaddr)); mutex_lock(&dmabuf->lock); if (--dmabuf->vmapping_counter == 0) { if (dmabuf->ops->vunmap) dmabuf->ops->vunmap(dmabuf, vaddr); - dmabuf->vmap_ptr = NULL; + dma_buf_map_clear(&dmabuf->vmap_ptr); } mutex_unlock(&dmabuf->lock); } diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h new file mode 100644 index 000000000000..d4b1bb3cc4b0 --- /dev/null +++ b/include/linux/dma-buf-map.h @@ -0,0 +1,87 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Pointer to dma-buf-mapped memory, plus helpers. + */ + +#ifndef __DMA_BUF_MAP_H__ +#define __DMA_BUF_MAP_H__ + +#include <linux/io.h> + +/** + * struct dma_buf_map - Pointer to vmap'ed dma-buf memory. + * @vaddr_iomem: The buffer's address if in I/O memory + * @vaddr: The buffer's address if in system memory + * @is_iomem: True if the dma-buf memory is located in I/O + * memory, or false otherwise. + * + * Calling dma-buf's vmap operation returns a pointer to the buffer. + * Depending on the location of the buffer, users may have to access it + * with I/O operations or memory load/store operations. struct dma_buf_map + * stores the buffer address and a flag that signals the required access. + */ +struct dma_buf_map { + union { + void __iomem *vaddr_iomem; + void *vaddr; + }; + bool is_iomem; +}; + +/* API transition helper */ +static inline bool dma_buf_map_is_vaddr(const struct dma_buf_map *map, const void *vaddr) +{ + return !map->is_iomem && (map->vaddr == vaddr); +} + +/** + * dma_buf_map_is_null - Tests for a dma-buf mapping to be NULL + * @map: The dma-buf mapping structure + * + * Depending on the state of struct dma_buf_map.is_iomem, tests if the + * mapping is NULL. + * + * Returns: + * True if the mapping is NULL, or false otherwise. + */ +static inline bool dma_buf_map_is_null(const struct dma_buf_map *map) +{ + if (map->is_iomem) + return map->vaddr_iomem == NULL; + return map->vaddr == NULL; +} + +/** + * dma_buf_map_is_set - Tests is the dma-buf mapping has been set + * @map: The dma-buf mapping structure + * + * Depending on the state of struct dma_buf_map.is_iomem, tests if the + * mapping has been set. + * + * Returns: + * True if the mapping is been set, or false otherwise. + */ +static inline bool dma_buf_map_is_set(const struct dma_buf_map *map) +{ + return !dma_buf_map_is_null(map); +} + +/** + * dma_buf_map_clear - Clears a dma-buf mapping structure + * @map: The dma-buf mapping structure + * + * Clears all fields to zero; including struct dma_buf_map.is_iomem. So + * mapping structures that were set to point to I/O memory are reset for + * system memory. Pointers are cleared to NULL. This is the default. + */ +static inline void dma_buf_map_clear(struct dma_buf_map *map) +{ + if (map->is_iomem) { + map->vaddr_iomem = NULL; + map->is_iomem = false; + } else { + map->vaddr = NULL; + } +} + +#endif /* __DMA_BUF_MAP_H__ */ diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 957b398d30e5..fcc2ddfb6d18 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -13,6 +13,7 @@ #ifndef __DMA_BUF_H__ #define __DMA_BUF_H__ +#include <linux/dma-buf-map.h> #include <linux/file.h> #include <linux/err.h> #include <linux/scatterlist.h> @@ -309,7 +310,7 @@ struct dma_buf { const struct dma_buf_ops *ops; struct mutex lock; unsigned vmapping_counter; - void *vmap_ptr; + struct dma_buf_map vmap_ptr; const char *exp_name; const char *name; spinlock_t name_lock;