shmem-helper: Switch to vmf_insert_pfn

Thomas Zimmermann Thu, 22 Jul 2021 11:22:50 -0700

Hi,

I'm not knowledgeable enougth to give this a full review. If you can just answer my questions, fell free to add an


Acked-by: Thomas Zimmermann <tzimmerm...@suse.de>

to the patch. :)

Am 13.07.21 um 22:51 schrieb Daniel Vetter:

We want to stop gup, which isn't the case if we use vmf_insert_page


What is gup?

and VM_MIXEDMAP, because that does not set pte_special.

v2: With this shmem gem helpers now definitely need CONFIG_MMU (0day)

v3: add more depends on MMU. For usb drivers this is a bit awkward,
but really it's correct: To be able to provide a contig mapping of
buffers to userspace on !MMU platforms we'd need to use the cma
helpers for these drivers on those platforms. As-is this wont work.

Also not exactly sure why vm_insert_page doesn't go boom, because that
definitely wont fly in practice since the pages are non-contig to
begin with.

Signed-off-by: Daniel Vetter <daniel.vet...@intel.com>
Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
Cc: Maxime Ripard <mrip...@kernel.org>
Cc: Thomas Zimmermann <tzimmerm...@suse.de>
Cc: David Airlie <airl...@linux.ie>
Cc: Daniel Vetter <dan...@ffwll.ch>
---
  drivers/gpu/drm/Kconfig                | 2 +-
  drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++--
  drivers/gpu/drm/gud/Kconfig            | 2 +-
  drivers/gpu/drm/tiny/Kconfig           | 4 ++--
  drivers/gpu/drm/udl/Kconfig            | 1 +
  5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 0d372354c2d0..314eefa39892 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -211,7 +211,7 @@ config DRM_KMS_CMA_HELPER

config DRM_GEM_SHMEM_HELPER

        bool
-       depends on DRM
+       depends on DRM && MMU
        help
          Choose this if you need the GEM shmem helper functions

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c

index d5e6d4568f99..296ab1b7c07f 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -542,7 +542,7 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
        } else {
                page = shmem->pages[page_offset];

- ret = vmf_insert_page(vma, vmf->address, page);

+               ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
        }

mutex_unlock(&shmem->pages_lock);

@@ -612,7 +612,7 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct 
vm_area_struct *vma)
                return ret;
        }

- vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;

+       vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND;
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        if (shmem->map_wc)
                vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
diff --git a/drivers/gpu/drm/gud/Kconfig b/drivers/gpu/drm/gud/Kconfig
index 1c8601bf4d91..9c1e61f9eec3 100644
--- a/drivers/gpu/drm/gud/Kconfig
+++ b/drivers/gpu/drm/gud/Kconfig
@@ -2,7 +2,7 @@

config DRM_GUD

        tristate "GUD USB Display"
-       depends on DRM && USB
+       depends on DRM && USB && MMU
        select LZ4_COMPRESS
        select DRM_KMS_HELPER
        select DRM_GEM_SHMEM_HELPER


I'm a kconfig noob, so this is rather a question than a review comment:

If DRM_GEM_SHMEM_HELPER already depends on MMU, this select will fail on non-MMU platforms? Why does the driver also depend on MMU? Simply to make the item disappear in menuconfig?


Best regards
Thomas

diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 5593128eeff9..c11fb5be7d09 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -44,7 +44,7 @@ config DRM_CIRRUS_QEMU

config DRM_GM12U320

        tristate "GM12U320 driver for USB projectors"
-       depends on DRM && USB
+       depends on DRM && USB && MMU
        select DRM_KMS_HELPER
        select DRM_GEM_SHMEM_HELPER
        help
@@ -53,7 +53,7 @@ config DRM_GM12U320

config DRM_SIMPLEDRM

        tristate "Simple framebuffer driver"
-       depends on DRM
+       depends on DRM && MMU
        select DRM_GEM_SHMEM_HELPER
        select DRM_KMS_HELPER
        help
diff --git a/drivers/gpu/drm/udl/Kconfig b/drivers/gpu/drm/udl/Kconfig
index 1f497d8f1ae5..c744175c6992 100644
--- a/drivers/gpu/drm/udl/Kconfig
+++ b/drivers/gpu/drm/udl/Kconfig
@@ -4,6 +4,7 @@ config DRM_UDL
        depends on DRM
        depends on USB
        depends on USB_ARCH_HAS_HCD
+       depends on MMU
        select DRM_GEM_SHMEM_HELPER
        select DRM_KMS_HELPER
        help


--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

OpenPGP_signature
Description: OpenPGP digital signature

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [Intel-gfx] [PATCH v4 2/4] drm/shmem-helper: Switch to vmf_insert_pfn

Reply via email to