Re: [PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
On Wed, Jan 27, 2021 at 09:29:41AM -0500, Andrey Grodzovsky wrote:
> Hey Daniel, just a ping.
Was on vacations last week.
> Andrey
>
> On 1/25/21 10:28 AM, Andrey Grodzovsky wrote:
> >
> > On 1/19/21 8:56 AM, Daniel Vetter wrote:
> > > On Mon, Jan 18, 2021 at 04:01:10PM -0500, Andrey Grodzovsky wrote:
> > > > On device removal reroute all CPU mappings to dummy page.
> > > >
> > > > v3:
> > > > Remove loop to find DRM file and instead access it
> > > > by vma->vm_file->private_data. Move dummy page installation
> > > > into a separate function.
> > > >
> > > > v4:
> > > > Map the entire BOs VA space into on demand allocated dummy page
> > > > on the first fault for that BO.
> > > >
> > > > Signed-off-by: Andrey Grodzovsky
> > > > ---
> > > > drivers/gpu/drm/ttm/ttm_bo_vm.c | 82
> > > > -
> > > > include/drm/ttm/ttm_bo_api.h | 2 +
> > > > 2 files changed, 83 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > index 6dc96cf..ed89da3 100644
> > > > --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > @@ -34,6 +34,8 @@
> > > > #include
> > > > #include
> > > > #include
> > > > +#include
> > > > +#include
> > > > #include
> > > > #include
> > > > #include
> > > > @@ -380,25 +382,103 @@ vm_fault_t
> > > > ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
> > > > }
> > > > EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
> > > > +static void ttm_bo_release_dummy_page(struct drm_device *dev, void
> > > > *res)
> > > > +{
> > > > + struct page *dummy_page = (struct page *)res;
> > > > +
> > > > + __free_page(dummy_page);
> > > > +}
> > > > +
> > > > +vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
> > > > +{
> > > > + struct vm_area_struct *vma = vmf->vma;
> > > > + struct ttm_buffer_object *bo = vma->vm_private_data;
> > > > + struct ttm_bo_device *bdev = bo->bdev;
> > > > + struct drm_device *ddev = bo->base.dev;
> > > > + vm_fault_t ret = VM_FAULT_NOPAGE;
> > > > + unsigned long address = vma->vm_start;
> > > > + unsigned long num_prefault = (vma->vm_end - vma->vm_start) >>
> > > > PAGE_SHIFT;
> > > > + unsigned long pfn;
> > > > + struct page *page;
> > > > + int i;
> > > > +
> > > > + /*
> > > > + * Wait for buffer data in transit, due to a pipelined
> > > > + * move.
> > > > + */
> > > > + ret = ttm_bo_vm_fault_idle(bo, vmf);
> > > > + if (unlikely(ret != 0))
> > > > + return ret;
> > > > +
> > > > + /* Allocate new dummy page to map all the VA range in this VMA to
> > > > it*/
> > > > + page = alloc_page(GFP_KERNEL | __GFP_ZERO);
> > > > + if (!page)
> > > > + return VM_FAULT_OOM;
> > > > +
> > > > + pfn = page_to_pfn(page);
> > > > +
> > > > + /*
> > > > + * Prefault the entire VMA range right away to avoid further faults
> > > > + */
> > > > + for (i = 0; i < num_prefault; ++i) {
> > > > +
> > > > + if (unlikely(address >= vma->vm_end))
> > > > + break;
> > > > +
> > > > + if (vma->vm_flags & VM_MIXEDMAP)
> > > > + ret = vmf_insert_mixed_prot(vma, address,
> > > > + __pfn_to_pfn_t(pfn, PFN_DEV),
> > > > + prot);
> > > > + else
> > > > + ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
> > > > +
> > > > + /* Never error on prefaulted PTEs */
> > > > + if (unlikely((ret & VM_FAULT_ERROR))) {
> > > > + if (i == 0)
> > > > + return VM_FAULT_NOPAGE;
> > > > + else
> > > > + break;
> > > > + }
> > > > +
> > > > + address += PAGE_SIZE;
> > > > + }
> > > > +
> > > > + /* Set the page to be freed using drmm release action */
> > > > + if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page,
> > > > page))
> > > > + return VM_FAULT_OOM;
> > > > +
> > > > + return ret;
> > > > +}
> > > > +EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
> > > I think we can lift this entire thing (once the ttm_bo_vm_fault_idle is
> > > gone) to the drm level, since nothing ttm specific in here. Probably stuff
> > > it into drm_gem.c (but really it's not even gem specific, it's fully
> > > generic "replace this vma with dummy pages pls" function.
> >
> >
> > Once I started with this I noticed that drmm_add_action_or_reset depends
> > on struct drm_device *ddev = bo->base.dev and bo is the private data
> > we embed at the TTM level when setting up the mapping and so this forces
> > to move drmm_add_action_or_reset out of this function to every client who
> > uses
> > this function, and then you separate the logic of page allocation from
> > it's release.
> > So I suggest we keep it as is.
Uh disappointing. Thing is, ttm essentially means drm devices with gem, except
for
vmwgfx, which is a drm_device without gem.
Re: [PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
Hey Daniel, just a ping.
Andrey
On 1/25/21 10:28 AM, Andrey Grodzovsky wrote:
On 1/19/21 8:56 AM, Daniel Vetter wrote:
On Mon, Jan 18, 2021 at 04:01:10PM -0500, Andrey Grodzovsky wrote:
On device removal reroute all CPU mappings to dummy page.
v3:
Remove loop to find DRM file and instead access it
by vma->vm_file->private_data. Move dummy page installation
into a separate function.
v4:
Map the entire BOs VA space into on demand allocated dummy page
on the first fault for that BO.
Signed-off-by: Andrey Grodzovsky
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 82
-
include/drm/ttm/ttm_bo_api.h | 2 +
2 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 6dc96cf..ed89da3 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -34,6 +34,8 @@
#include
#include
#include
+#include
+#include
#include
#include
#include
@@ -380,25 +382,103 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault
*vmf,
}
EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
+static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
+{
+ struct page *dummy_page = (struct page *)res;
+
+ __free_page(dummy_page);
+}
+
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct ttm_bo_device *bdev = bo->bdev;
+ struct drm_device *ddev = bo->base.dev;
+ vm_fault_t ret = VM_FAULT_NOPAGE;
+ unsigned long address = vma->vm_start;
+ unsigned long num_prefault = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+ unsigned long pfn;
+ struct page *page;
+ int i;
+
+ /*
+ * Wait for buffer data in transit, due to a pipelined
+ * move.
+ */
+ ret = ttm_bo_vm_fault_idle(bo, vmf);
+ if (unlikely(ret != 0))
+ return ret;
+
+ /* Allocate new dummy page to map all the VA range in this VMA to it*/
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return VM_FAULT_OOM;
+
+ pfn = page_to_pfn(page);
+
+ /*
+ * Prefault the entire VMA range right away to avoid further faults
+ */
+ for (i = 0; i < num_prefault; ++i) {
+
+ if (unlikely(address >= vma->vm_end))
+ break;
+
+ if (vma->vm_flags & VM_MIXEDMAP)
+ ret = vmf_insert_mixed_prot(vma, address,
+ __pfn_to_pfn_t(pfn, PFN_DEV),
+ prot);
+ else
+ ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
+
+ /* Never error on prefaulted PTEs */
+ if (unlikely((ret & VM_FAULT_ERROR))) {
+ if (i == 0)
+ return VM_FAULT_NOPAGE;
+ else
+ break;
+ }
+
+ address += PAGE_SIZE;
+ }
+
+ /* Set the page to be freed using drmm release action */
+ if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
+ return VM_FAULT_OOM;
+
+ return ret;
+}
+EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
I think we can lift this entire thing (once the ttm_bo_vm_fault_idle is
gone) to the drm level, since nothing ttm specific in here. Probably stuff
it into drm_gem.c (but really it's not even gem specific, it's fully
generic "replace this vma with dummy pages pls" function.
Once I started with this I noticed that drmm_add_action_or_reset depends
on struct drm_device *ddev = bo->base.dev and bo is the private data
we embed at the TTM level when setting up the mapping and so this forces
to move drmm_add_action_or_reset out of this function to every client who uses
this function, and then you separate the logic of page allocation from it's
release.
So I suggest we keep it as is.
Andrey
Aside from this nit I think the overall approach you have here is starting
to look good. Lots of work, but imo we're getting there and can
start landing stuff soon.
-Daniel
+
vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
pgprot_t prot;
struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct drm_device *ddev = bo->base.dev;
vm_fault_t ret;
+ int idx;
ret = ttm_bo_vm_reserve(bo, vmf);
if (ret)
return ret;
prot = vma->vm_page_prot;
- ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
+ if (drm_dev_enter(ddev, )) {
+ ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
+ drm_dev_exit(idx);
+ } else {
+ ret = ttm_bo_vm_dummy_page(vmf, prot);
+ }
if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
return ret;
dma_resv_unlock(bo->base.resv);
return ret;
+
+ return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_fault);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index e17be32..12fb240 100644
Re: [PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
On 1/19/21 8:56 AM, Daniel Vetter wrote:
On Mon, Jan 18, 2021 at 04:01:10PM -0500, Andrey Grodzovsky wrote:
On device removal reroute all CPU mappings to dummy page.
v3:
Remove loop to find DRM file and instead access it
by vma->vm_file->private_data. Move dummy page installation
into a separate function.
v4:
Map the entire BOs VA space into on demand allocated dummy page
on the first fault for that BO.
Signed-off-by: Andrey Grodzovsky
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 82 -
include/drm/ttm/ttm_bo_api.h| 2 +
2 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 6dc96cf..ed89da3 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -34,6 +34,8 @@
#include
#include
#include
+#include
+#include
#include
#include
#include
@@ -380,25 +382,103 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
}
EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
+static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
+{
+ struct page *dummy_page = (struct page *)res;
+
+ __free_page(dummy_page);
+}
+
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct ttm_bo_device *bdev = bo->bdev;
+ struct drm_device *ddev = bo->base.dev;
+ vm_fault_t ret = VM_FAULT_NOPAGE;
+ unsigned long address = vma->vm_start;
+ unsigned long num_prefault = (vma->vm_end - vma->vm_start) >>
PAGE_SHIFT;
+ unsigned long pfn;
+ struct page *page;
+ int i;
+
+ /*
+* Wait for buffer data in transit, due to a pipelined
+* move.
+*/
+ ret = ttm_bo_vm_fault_idle(bo, vmf);
+ if (unlikely(ret != 0))
+ return ret;
+
+ /* Allocate new dummy page to map all the VA range in this VMA to it*/
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return VM_FAULT_OOM;
+
+ pfn = page_to_pfn(page);
+
+ /*
+* Prefault the entire VMA range right away to avoid further faults
+*/
+ for (i = 0; i < num_prefault; ++i) {
+
+ if (unlikely(address >= vma->vm_end))
+ break;
+
+ if (vma->vm_flags & VM_MIXEDMAP)
+ ret = vmf_insert_mixed_prot(vma, address,
+ __pfn_to_pfn_t(pfn,
PFN_DEV),
+ prot);
+ else
+ ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
+
+ /* Never error on prefaulted PTEs */
+ if (unlikely((ret & VM_FAULT_ERROR))) {
+ if (i == 0)
+ return VM_FAULT_NOPAGE;
+ else
+ break;
+ }
+
+ address += PAGE_SIZE;
+ }
+
+ /* Set the page to be freed using drmm release action */
+ if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
+ return VM_FAULT_OOM;
+
+ return ret;
+}
+EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
I think we can lift this entire thing (once the ttm_bo_vm_fault_idle is
gone) to the drm level, since nothing ttm specific in here. Probably stuff
it into drm_gem.c (but really it's not even gem specific, it's fully
generic "replace this vma with dummy pages pls" function.
Once I started with this I noticed that drmm_add_action_or_reset depends
on struct drm_device *ddev = bo->base.dev and bo is the private data
we embed at the TTM level when setting up the mapping and so this forces
to move drmm_add_action_or_reset out of this function to every client who uses
this function, and then you separate the logic of page allocation from it's
release.
So I suggest we keep it as is.
Andrey
Aside from this nit I think the overall approach you have here is starting
to look good. Lots of work, but imo we're getting there and can
start landing stuff soon.
-Daniel
+
vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
pgprot_t prot;
struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct drm_device *ddev = bo->base.dev;
vm_fault_t ret;
+ int idx;
ret = ttm_bo_vm_reserve(bo, vmf);
if (ret)
return ret;
prot = vma->vm_page_prot;
- ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
+ if (drm_dev_enter(ddev, )) {
+ ret = ttm_bo_vm_fault_reserved(vmf, prot,
TTM_BO_VM_NUM_PREFAULT, 1);
+ drm_dev_exit(idx);
+ } else {
+ ret = ttm_bo_vm_dummy_page(vmf, prot);
+ }
if (ret == VM_FAULT_RETRY && !(vmf->flags &
Re: [PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
On Mon, Jan 18, 2021 at 04:01:10PM -0500, Andrey Grodzovsky wrote:
> On device removal reroute all CPU mappings to dummy page.
>
> v3:
> Remove loop to find DRM file and instead access it
> by vma->vm_file->private_data. Move dummy page installation
> into a separate function.
>
> v4:
> Map the entire BOs VA space into on demand allocated dummy page
> on the first fault for that BO.
>
> Signed-off-by: Andrey Grodzovsky
> ---
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 82
> -
> include/drm/ttm/ttm_bo_api.h| 2 +
> 2 files changed, 83 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 6dc96cf..ed89da3 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -34,6 +34,8 @@
> #include
> #include
> #include
> +#include
> +#include
> #include
> #include
> #include
> @@ -380,25 +382,103 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault
> *vmf,
> }
> EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
>
> +static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
> +{
> + struct page *dummy_page = (struct page *)res;
> +
> + __free_page(dummy_page);
> +}
> +
> +vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
> +{
> + struct vm_area_struct *vma = vmf->vma;
> + struct ttm_buffer_object *bo = vma->vm_private_data;
> + struct ttm_bo_device *bdev = bo->bdev;
> + struct drm_device *ddev = bo->base.dev;
> + vm_fault_t ret = VM_FAULT_NOPAGE;
> + unsigned long address = vma->vm_start;
> + unsigned long num_prefault = (vma->vm_end - vma->vm_start) >>
> PAGE_SHIFT;
> + unsigned long pfn;
> + struct page *page;
> + int i;
> +
> + /*
> + * Wait for buffer data in transit, due to a pipelined
> + * move.
> + */
> + ret = ttm_bo_vm_fault_idle(bo, vmf);
> + if (unlikely(ret != 0))
> + return ret;
> +
> + /* Allocate new dummy page to map all the VA range in this VMA to it*/
> + page = alloc_page(GFP_KERNEL | __GFP_ZERO);
> + if (!page)
> + return VM_FAULT_OOM;
> +
> + pfn = page_to_pfn(page);
> +
> + /*
> + * Prefault the entire VMA range right away to avoid further faults
> + */
> + for (i = 0; i < num_prefault; ++i) {
> +
> + if (unlikely(address >= vma->vm_end))
> + break;
> +
> + if (vma->vm_flags & VM_MIXEDMAP)
> + ret = vmf_insert_mixed_prot(vma, address,
> + __pfn_to_pfn_t(pfn,
> PFN_DEV),
> + prot);
> + else
> + ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
> +
> + /* Never error on prefaulted PTEs */
> + if (unlikely((ret & VM_FAULT_ERROR))) {
> + if (i == 0)
> + return VM_FAULT_NOPAGE;
> + else
> + break;
> + }
> +
> + address += PAGE_SIZE;
> + }
> +
> + /* Set the page to be freed using drmm release action */
> + if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
> + return VM_FAULT_OOM;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
I think we can lift this entire thing (once the ttm_bo_vm_fault_idle is
gone) to the drm level, since nothing ttm specific in here. Probably stuff
it into drm_gem.c (but really it's not even gem specific, it's fully
generic "replace this vma with dummy pages pls" function.
Aside from this nit I think the overall approach you have here is starting
to look good. Lots of work, but imo we're getting there and can
start landing stuff soon.
-Daniel
> +
> vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> pgprot_t prot;
> struct ttm_buffer_object *bo = vma->vm_private_data;
> + struct drm_device *ddev = bo->base.dev;
> vm_fault_t ret;
> + int idx;
>
> ret = ttm_bo_vm_reserve(bo, vmf);
> if (ret)
> return ret;
>
> prot = vma->vm_page_prot;
> - ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
> + if (drm_dev_enter(ddev, )) {
> + ret = ttm_bo_vm_fault_reserved(vmf, prot,
> TTM_BO_VM_NUM_PREFAULT, 1);
> + drm_dev_exit(idx);
> + } else {
> + ret = ttm_bo_vm_dummy_page(vmf, prot);
> + }
> if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
> return ret;
>
> dma_resv_unlock(bo->base.resv);
>
> return ret;
> +
> + return ret;
> }
> EXPORT_SYMBOL(ttm_bo_vm_fault);
>
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index e17be32..12fb240 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++
Re: [PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
Am 18.01.21 um 22:01 schrieb Andrey Grodzovsky:
On device removal reroute all CPU mappings to dummy page.
v3:
Remove loop to find DRM file and instead access it
by vma->vm_file->private_data. Move dummy page installation
into a separate function.
v4:
Map the entire BOs VA space into on demand allocated dummy page
on the first fault for that BO.
Signed-off-by: Andrey Grodzovsky
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 82 -
include/drm/ttm/ttm_bo_api.h| 2 +
2 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 6dc96cf..ed89da3 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -34,6 +34,8 @@
#include
#include
#include
+#include
+#include
#include
#include
#include
@@ -380,25 +382,103 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
}
EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
+static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
+{
+ struct page *dummy_page = (struct page *)res;
+
+ __free_page(dummy_page);
+}
+
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct ttm_bo_device *bdev = bo->bdev;
+ struct drm_device *ddev = bo->base.dev;
+ vm_fault_t ret = VM_FAULT_NOPAGE;
+ unsigned long address = vma->vm_start;
+ unsigned long num_prefault = (vma->vm_end - vma->vm_start) >>
PAGE_SHIFT;
+ unsigned long pfn;
+ struct page *page;
+ int i;
+
+ /*
+* Wait for buffer data in transit, due to a pipelined
+* move.
+*/
+ ret = ttm_bo_vm_fault_idle(bo, vmf);
+ if (unlikely(ret != 0))
+ return ret;
This is superfluous and probably quite harmful here because we wait for
the hardware to do something.
We map a dummy page instead of the real BO content to the whole range
anyway, so no need to wait for the real BO content to show up.
+
+ /* Allocate new dummy page to map all the VA range in this VMA to it*/
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return VM_FAULT_OOM;
+
+ pfn = page_to_pfn(page);
+
+ /*
+* Prefault the entire VMA range right away to avoid further faults
+*/
+ for (i = 0; i < num_prefault; ++i) {
Maybe rename the variable to num_pages. I was confused for a moment why
we still prefault.
Alternative you can just drop i and do "for (addr = vma->vm_start; addr
< vma->vm_end; addr += PAGE_SIZE)".
+
+ if (unlikely(address >= vma->vm_end))
+ break;
+
+ if (vma->vm_flags & VM_MIXEDMAP)
+ ret = vmf_insert_mixed_prot(vma, address,
+ __pfn_to_pfn_t(pfn,
PFN_DEV),
+ prot);
+ else
+ ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
+
+ /* Never error on prefaulted PTEs */
+ if (unlikely((ret & VM_FAULT_ERROR))) {
+ if (i == 0)
+ return VM_FAULT_NOPAGE;
+ else
+ break;
This should probably be modified to either always return the error or
always ignore it.
Apart from that looks good to me.
Christian.
+ }
+
+ address += PAGE_SIZE;
+ }
+
+ /* Set the page to be freed using drmm release action */
+ if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
+ return VM_FAULT_OOM;
+
+ return ret;
+}
+EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
+
vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
pgprot_t prot;
struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct drm_device *ddev = bo->base.dev;
vm_fault_t ret;
+ int idx;
ret = ttm_bo_vm_reserve(bo, vmf);
if (ret)
return ret;
prot = vma->vm_page_prot;
- ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
+ if (drm_dev_enter(ddev, )) {
+ ret = ttm_bo_vm_fault_reserved(vmf, prot,
TTM_BO_VM_NUM_PREFAULT, 1);
+ drm_dev_exit(idx);
+ } else {
+ ret = ttm_bo_vm_dummy_page(vmf, prot);
+ }
if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
return ret;
dma_resv_unlock(bo->base.resv);
return ret;
+
+ return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_fault);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index e17be32..12fb240 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@
Re: [PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
On Mon, Jan 18, 2021 at 4:02 PM Andrey Grodzovsky
wrote:
>
> On device removal reroute all CPU mappings to dummy page.
>
> v3:
> Remove loop to find DRM file and instead access it
> by vma->vm_file->private_data. Move dummy page installation
> into a separate function.
>
> v4:
> Map the entire BOs VA space into on demand allocated dummy page
> on the first fault for that BO.
>
> Signed-off-by: Andrey Grodzovsky
> ---
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 82
> -
> include/drm/ttm/ttm_bo_api.h| 2 +
> 2 files changed, 83 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 6dc96cf..ed89da3 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -34,6 +34,8 @@
> #include
> #include
> #include
> +#include
> +#include
> #include
> #include
> #include
> @@ -380,25 +382,103 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault
> *vmf,
> }
> EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
>
> +static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
> +{
> + struct page *dummy_page = (struct page *)res;
> +
> + __free_page(dummy_page);
> +}
> +
> +vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
> +{
> + struct vm_area_struct *vma = vmf->vma;
> + struct ttm_buffer_object *bo = vma->vm_private_data;
> + struct ttm_bo_device *bdev = bo->bdev;
> + struct drm_device *ddev = bo->base.dev;
> + vm_fault_t ret = VM_FAULT_NOPAGE;
> + unsigned long address = vma->vm_start;
> + unsigned long num_prefault = (vma->vm_end - vma->vm_start) >>
> PAGE_SHIFT;
> + unsigned long pfn;
> + struct page *page;
> + int i;
> +
> + /*
> +* Wait for buffer data in transit, due to a pipelined
> +* move.
> +*/
> + ret = ttm_bo_vm_fault_idle(bo, vmf);
> + if (unlikely(ret != 0))
> + return ret;
> +
> + /* Allocate new dummy page to map all the VA range in this VMA to it*/
> + page = alloc_page(GFP_KERNEL | __GFP_ZERO);
> + if (!page)
> + return VM_FAULT_OOM;
> +
> + pfn = page_to_pfn(page);
> +
> + /*
> +* Prefault the entire VMA range right away to avoid further faults
> +*/
> + for (i = 0; i < num_prefault; ++i) {
> +
> + if (unlikely(address >= vma->vm_end))
> + break;
> +
> + if (vma->vm_flags & VM_MIXEDMAP)
> + ret = vmf_insert_mixed_prot(vma, address,
> + __pfn_to_pfn_t(pfn,
> PFN_DEV),
> + prot);
> + else
> + ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
> +
> + /* Never error on prefaulted PTEs */
> + if (unlikely((ret & VM_FAULT_ERROR))) {
> + if (i == 0)
> + return VM_FAULT_NOPAGE;
> + else
> + break;
> + }
> +
> + address += PAGE_SIZE;
> + }
> +
> + /* Set the page to be freed using drmm release action */
> + if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
> + return VM_FAULT_OOM;
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
> +
> vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> pgprot_t prot;
> struct ttm_buffer_object *bo = vma->vm_private_data;
> + struct drm_device *ddev = bo->base.dev;
> vm_fault_t ret;
> + int idx;
>
> ret = ttm_bo_vm_reserve(bo, vmf);
> if (ret)
> return ret;
>
> prot = vma->vm_page_prot;
> - ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
> + if (drm_dev_enter(ddev, )) {
> + ret = ttm_bo_vm_fault_reserved(vmf, prot,
> TTM_BO_VM_NUM_PREFAULT, 1);
> + drm_dev_exit(idx);
> + } else {
> + ret = ttm_bo_vm_dummy_page(vmf, prot);
> + }
> if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
> return ret;
>
> dma_resv_unlock(bo->base.resv);
>
> return ret;
> +
> + return ret;
Duplicate return here.
Alex
> }
> EXPORT_SYMBOL(ttm_bo_vm_fault);
>
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index e17be32..12fb240 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -643,4 +643,6 @@ void ttm_bo_vm_close(struct vm_area_struct *vma);
> int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> void *buf, int len, int write);
>
> +vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot);
> +
> #endif
[PATCH v4 01/14] drm/ttm: Remap all page faults to per process dummy page.
On device removal reroute all CPU mappings to dummy page.
v3:
Remove loop to find DRM file and instead access it
by vma->vm_file->private_data. Move dummy page installation
into a separate function.
v4:
Map the entire BOs VA space into on demand allocated dummy page
on the first fault for that BO.
Signed-off-by: Andrey Grodzovsky
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 82 -
include/drm/ttm/ttm_bo_api.h| 2 +
2 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 6dc96cf..ed89da3 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -34,6 +34,8 @@
#include
#include
#include
+#include
+#include
#include
#include
#include
@@ -380,25 +382,103 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
}
EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
+static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
+{
+ struct page *dummy_page = (struct page *)res;
+
+ __free_page(dummy_page);
+}
+
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct ttm_bo_device *bdev = bo->bdev;
+ struct drm_device *ddev = bo->base.dev;
+ vm_fault_t ret = VM_FAULT_NOPAGE;
+ unsigned long address = vma->vm_start;
+ unsigned long num_prefault = (vma->vm_end - vma->vm_start) >>
PAGE_SHIFT;
+ unsigned long pfn;
+ struct page *page;
+ int i;
+
+ /*
+* Wait for buffer data in transit, due to a pipelined
+* move.
+*/
+ ret = ttm_bo_vm_fault_idle(bo, vmf);
+ if (unlikely(ret != 0))
+ return ret;
+
+ /* Allocate new dummy page to map all the VA range in this VMA to it*/
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return VM_FAULT_OOM;
+
+ pfn = page_to_pfn(page);
+
+ /*
+* Prefault the entire VMA range right away to avoid further faults
+*/
+ for (i = 0; i < num_prefault; ++i) {
+
+ if (unlikely(address >= vma->vm_end))
+ break;
+
+ if (vma->vm_flags & VM_MIXEDMAP)
+ ret = vmf_insert_mixed_prot(vma, address,
+ __pfn_to_pfn_t(pfn,
PFN_DEV),
+ prot);
+ else
+ ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
+
+ /* Never error on prefaulted PTEs */
+ if (unlikely((ret & VM_FAULT_ERROR))) {
+ if (i == 0)
+ return VM_FAULT_NOPAGE;
+ else
+ break;
+ }
+
+ address += PAGE_SIZE;
+ }
+
+ /* Set the page to be freed using drmm release action */
+ if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
+ return VM_FAULT_OOM;
+
+ return ret;
+}
+EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
+
vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
pgprot_t prot;
struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct drm_device *ddev = bo->base.dev;
vm_fault_t ret;
+ int idx;
ret = ttm_bo_vm_reserve(bo, vmf);
if (ret)
return ret;
prot = vma->vm_page_prot;
- ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
+ if (drm_dev_enter(ddev, )) {
+ ret = ttm_bo_vm_fault_reserved(vmf, prot,
TTM_BO_VM_NUM_PREFAULT, 1);
+ drm_dev_exit(idx);
+ } else {
+ ret = ttm_bo_vm_dummy_page(vmf, prot);
+ }
if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
return ret;
dma_resv_unlock(bo->base.resv);
return ret;
+
+ return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_fault);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index e17be32..12fb240 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -643,4 +643,6 @@ void ttm_bo_vm_close(struct vm_area_struct *vma);
int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write);
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot);
+
#endif
--
2.7.4
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