[PATCH v4 8/9] drm/panfrost: Add support for GPU heap allocations
Steven Price
steven.price at arm.com
Fri Aug 9 10:31:22 UTC 2019
On 08/08/2019 23:21, Rob Herring wrote:
> The midgard/bifrost GPUs need to allocate GPU heap memory which is
> allocated on GPU page faults and not pinned in memory. The vendor driver
> calls this functionality GROW_ON_GPF.
>
> This implementation assumes that BOs allocated with the
> PANFROST_BO_NOEXEC flag are never mmapped or exported. Both of those may
> actually work, but I'm unsure if there's some interaction there. It
> would cause the whole object to be pinned in memory which would defeat
> the point of this.
>
> On faults, we map in 2MB at a time in order to utilize huge pages (if
> enabled). Currently, once we've mapped pages in, they are only unmapped
> if the BO is freed. Once we add shrinker support, we can unmap pages
> with the shrinker.
>
> Cc: Tomeu Vizoso <tomeu.vizoso at collabora.com>
> Cc: Boris Brezillon <boris.brezillon at collabora.com>
> Cc: Robin Murphy <robin.murphy at arm.com>
> Cc: Steven Price <steven.price at arm.com>
> Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
> Signed-off-by: Rob Herring <robh at kernel.org>
Reviewed-by: Steven Price <steven.price at arm.com>
Although a couple of comments below...
> ---
> drivers/gpu/drm/panfrost/TODO | 2 -
> drivers/gpu/drm/panfrost/panfrost_drv.c | 11 +-
> drivers/gpu/drm/panfrost/panfrost_gem.c | 43 +++++++-
> drivers/gpu/drm/panfrost/panfrost_gem.h | 8 ++
> drivers/gpu/drm/panfrost/panfrost_mmu.c | 129 ++++++++++++++++++++++--
> include/uapi/drm/panfrost_drm.h | 1 +
> 6 files changed, 177 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/panfrost/TODO b/drivers/gpu/drm/panfrost/TODO
> index d4c7fb7e7d13..e7727b292355 100644
> --- a/drivers/gpu/drm/panfrost/TODO
> +++ b/drivers/gpu/drm/panfrost/TODO
> @@ -10,8 +10,6 @@
> The hard part is handling when more address spaces are needed than what
> the h/w provides.
>
> -- Support pinning pages on demand (GPU page faults).
> -
> - Support userspace controlled GPU virtual addresses. Needed for Vulkan. (Tomeu)
>
> - Compute job support. So called 'compute only' jobs need to be plumbed up to
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index f070f2dd9f84..994dbc37e4d0 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -82,7 +82,12 @@ static int panfrost_ioctl_create_bo(struct drm_device *dev, void *data,
> struct drm_panfrost_create_bo *args = data;
>
> if (!args->size || args->pad ||
> - (args->flags & ~PANFROST_BO_NOEXEC))
> + (args->flags & ~(PANFROST_BO_NOEXEC | PANFROST_BO_HEAP)))
> + return -EINVAL;
> +
> + /* Heaps should never be executable */
> + if ((args->flags & PANFROST_BO_HEAP) &&
> + !(args->flags & PANFROST_BO_NOEXEC))
> return -EINVAL;
>
> bo = panfrost_gem_create_with_handle(file, dev, args->size, args->flags,
> @@ -297,6 +302,10 @@ static int panfrost_ioctl_mmap_bo(struct drm_device *dev, void *data,
> return -ENOENT;
> }
>
> + /* Don't allow mmapping of heap objects as pages are not pinned. */
> + if (to_panfrost_bo(gem_obj)->is_heap)
> + return -EINVAL;
> +
> ret = drm_gem_create_mmap_offset(gem_obj);
> if (ret == 0)
> args->offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index f398109b8e0c..37a3a6ed4617 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -16,6 +16,23 @@
> */
> static void panfrost_gem_free_object(struct drm_gem_object *obj)
> {
> + struct panfrost_gem_object *bo = to_panfrost_bo(obj);
> + struct panfrost_device *pfdev = obj->dev->dev_private;
This is where things start building again - these need moving to patch 3.
> +
> + if (bo->sgts) {
> + int i;
> + int n_sgt = bo->base.base.size / SZ_2M;
> +
> + for (i = 0; i < n_sgt; i++) {
> + if (bo->sgts[i].sgl) {
> + dma_unmap_sg(pfdev->dev, bo->sgts[i].sgl,
> + bo->sgts[i].nents, DMA_BIDIRECTIONAL);
> + sg_free_table(&bo->sgts[i]);
> + }
> + }
> + kfree(bo->sgts);
> + }
> +
> mutex_lock(&pfdev->shrinker_lock);
> if (!list_empty(&bo->base.madv_list))
> list_del(&bo->base.madv_list);
> @@ -50,10 +67,11 @@ static int panfrost_gem_open(struct drm_gem_object *obj, struct drm_file *file_p
> if (ret)
> goto out;
>
> - ret = panfrost_mmu_map(bo);
> - if (ret)
> - drm_mm_remove_node(&bo->node);
> -
> + if (!bo->is_heap) {
> + ret = panfrost_mmu_map(bo);
> + if (ret)
> + drm_mm_remove_node(&bo->node);
> + }
> out:
> spin_unlock(&pfdev->mm_lock);
> return ret;
> @@ -73,12 +91,20 @@ static void panfrost_gem_close(struct drm_gem_object *obj, struct drm_file *file
> spin_unlock(&pfdev->mm_lock);
> }
>
> +static int panfrost_gem_pin(struct drm_gem_object *obj)
> +{
> + if (to_panfrost_bo(obj)->is_heap)
> + return -EINVAL;
> +
> + return drm_gem_shmem_pin(obj);
> +}
> +
> static const struct drm_gem_object_funcs panfrost_gem_funcs = {
> .free = panfrost_gem_free_object,
> .open = panfrost_gem_open,
> .close = panfrost_gem_close,
> .print_info = drm_gem_shmem_print_info,
> - .pin = drm_gem_shmem_pin,
> + .pin = panfrost_gem_pin,
> .unpin = drm_gem_shmem_unpin,
> .get_sg_table = drm_gem_shmem_get_sg_table,
> .vmap = drm_gem_shmem_vmap,
> @@ -117,12 +143,19 @@ panfrost_gem_create_with_handle(struct drm_file *file_priv,
> struct drm_gem_shmem_object *shmem;
> struct panfrost_gem_object *bo;
>
> + /* Round up heap allocations to 2MB to keep fault handling simple */
> + if (flags & PANFROST_BO_HEAP)
> + size = roundup(size, SZ_2M);
> + else
> + size = roundup(size, PAGE_SIZE);
If I understand correctly this roundup to PAGE_SIZE is now redundant
(although not harmful).
Steve
> +
> shmem = drm_gem_shmem_create(dev, size);
> if (IS_ERR(shmem))
> return ERR_CAST(shmem);
>
> bo = to_panfrost_bo(&shmem->base);
> bo->noexec = !!(flags & PANFROST_BO_NOEXEC);
> + bo->is_heap = !!(flags & PANFROST_BO_HEAP);
>
> /*
> * Allocate an id of idr table where the obj is registered
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> index d4c7aa1790a7..e10f58316915 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> @@ -9,10 +9,12 @@
>
> struct panfrost_gem_object {
> struct drm_gem_shmem_object base;
> + struct sg_table *sgts;
>
> struct drm_mm_node node;
> bool is_mapped :1;
> bool noexec :1;
> + bool is_heap :1;
> };
>
> static inline
> @@ -21,6 +23,12 @@ struct panfrost_gem_object *to_panfrost_bo(struct drm_gem_object *obj)
> return container_of(to_drm_gem_shmem_obj(obj), struct panfrost_gem_object, base);
> }
>
> +static inline
> +struct panfrost_gem_object *drm_mm_node_to_panfrost_bo(struct drm_mm_node *node)
> +{
> + return container_of(node, struct panfrost_gem_object, node);
> +}
> +
> struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t size);
>
> struct drm_gem_object *
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index b609ee55a872..2ed411f09d80 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -2,6 +2,7 @@
> /* Copyright 2019 Linaro, Ltd, Rob Herring <robh at kernel.org> */
> #include <linux/bitfield.h>
> #include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> #include <linux/interrupt.h>
> #include <linux/io.h>
> #include <linux/iopoll.h>
> @@ -9,6 +10,7 @@
> #include <linux/iommu.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> +#include <linux/shmem_fs.h>
> #include <linux/sizes.h>
>
> #include "panfrost_device.h"
> @@ -240,12 +242,12 @@ void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
> size_t unmapped_page;
> size_t pgsize = get_pgsize(iova, len - unmapped_len);
>
> - unmapped_page = ops->unmap(ops, iova, pgsize);
> - if (!unmapped_page)
> - break;
> -
> - iova += unmapped_page;
> - unmapped_len += unmapped_page;
> + if (ops->iova_to_phys(ops, iova)) {
> + unmapped_page = ops->unmap(ops, iova, pgsize);
> + WARN_ON(unmapped_page != pgsize);
> + }
> + iova += pgsize;
> + unmapped_len += pgsize;
> }
>
> mmu_hw_do_operation(pfdev, 0, bo->node.start << PAGE_SHIFT,
> @@ -281,6 +283,105 @@ static const struct iommu_gather_ops mmu_tlb_ops = {
> .tlb_sync = mmu_tlb_sync_context,
> };
>
> +static struct drm_mm_node *addr_to_drm_mm_node(struct panfrost_device *pfdev, int as, u64 addr)
> +{
> + struct drm_mm_node *node;
> + u64 offset = addr >> PAGE_SHIFT;
> +
> + drm_mm_for_each_node(node, &pfdev->mm) {
> + if (offset >= node->start && offset < (node->start + node->size))
> + return node;
> + }
> + return NULL;
> +}
> +
> +#define NUM_FAULT_PAGES (SZ_2M / PAGE_SIZE)
> +
> +int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, u64 addr)
> +{
> + int ret, i;
> + struct drm_mm_node *node;
> + struct panfrost_gem_object *bo;
> + struct address_space *mapping;
> + pgoff_t page_offset;
> + struct sg_table *sgt;
> + struct page **pages;
> +
> + node = addr_to_drm_mm_node(pfdev, as, addr);
> + if (!node)
> + return -ENOENT;
> +
> + bo = drm_mm_node_to_panfrost_bo(node);
> + if (!bo->is_heap) {
> + dev_WARN(pfdev->dev, "matching BO is not heap type (GPU VA = %llx)",
> + node->start << PAGE_SHIFT);
> + return -EINVAL;
> + }
> + /* Assume 2MB alignment and size multiple */
> + addr &= ~((u64)SZ_2M - 1);
> + page_offset = addr >> PAGE_SHIFT;
> + page_offset -= node->start;
> +
> + mutex_lock(&bo->base.pages_lock);
> +
> + if (!bo->base.pages) {
> + bo->sgts = kvmalloc_array(bo->base.base.size / SZ_2M,
> + sizeof(struct sg_table), GFP_KERNEL | __GFP_ZERO);
> + if (!bo->sgts)
> + return -ENOMEM;
> +
> + pages = kvmalloc_array(bo->base.base.size >> PAGE_SHIFT,
> + sizeof(struct page *), GFP_KERNEL | __GFP_ZERO);
> + if (!pages) {
> + kfree(bo->sgts);
> + bo->sgts = NULL;
> + return -ENOMEM;
> + }
> + bo->base.pages = pages;
> + bo->base.pages_use_count = 1;
> + } else
> + pages = bo->base.pages;
> +
> + mapping = bo->base.base.filp->f_mapping;
> + mapping_set_unevictable(mapping);
> +
> + for (i = page_offset; i < page_offset + NUM_FAULT_PAGES; i++) {
> + pages[i] = shmem_read_mapping_page(mapping, i);
> + if (IS_ERR(pages[i])) {
> + mutex_unlock(&bo->base.pages_lock);
> + ret = PTR_ERR(pages[i]);
> + goto err_pages;
> + }
> + }
> +
> + mutex_unlock(&bo->base.pages_lock);
> +
> + sgt = &bo->sgts[page_offset / (SZ_2M / PAGE_SIZE)];
> + ret = sg_alloc_table_from_pages(sgt, pages + page_offset,
> + NUM_FAULT_PAGES, 0, SZ_2M, GFP_KERNEL);
> + if (ret)
> + goto err_pages;
> +
> + if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) {
> + ret = -EINVAL;
> + goto err_map;
> + }
> +
> + mmu_map_sg(pfdev, addr, IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);
> +
> + bo->is_mapped = true;
> +
> + dev_dbg(pfdev->dev, "mapped page fault @ %llx", addr);
> +
> + return 0;
> +
> +err_map:
> + sg_free_table(sgt);
> +err_pages:
> + drm_gem_shmem_put_pages(&bo->base);
> + return ret;
> +}
> +
> static const char *access_type_name(struct panfrost_device *pfdev,
> u32 fault_status)
> {
> @@ -317,9 +418,7 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data)
> {
> struct panfrost_device *pfdev = data;
> u32 status = mmu_read(pfdev, MMU_INT_RAWSTAT);
> - int i;
> -
> - dev_err(pfdev->dev, "mmu irq status=%x\n", status);
> + int i, ret;
>
> for (i = 0; status; i++) {
> u32 mask = BIT(i) | BIT(i + 16);
> @@ -341,6 +440,18 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data)
> access_type = (fault_status >> 8) & 0x3;
> source_id = (fault_status >> 16);
>
> + /* Page fault only */
> + if ((status & mask) == BIT(i)) {
> + WARN_ON(exception_type < 0xC1 || exception_type > 0xC4);
> +
> + ret = panfrost_mmu_map_fault_addr(pfdev, i, addr);
> + if (!ret) {
> + mmu_write(pfdev, MMU_INT_CLEAR, BIT(i));
> + status &= ~mask;
> + continue;
> + }
> + }
> +
> /* terminal fault, print info about the fault */
> dev_err(pfdev->dev,
> "Unhandled Page fault in AS%d at VA 0x%016llX\n"
> diff --git a/include/uapi/drm/panfrost_drm.h b/include/uapi/drm/panfrost_drm.h
> index b80c20d17dec..ec19db1eead8 100644
> --- a/include/uapi/drm/panfrost_drm.h
> +++ b/include/uapi/drm/panfrost_drm.h
> @@ -85,6 +85,7 @@ struct drm_panfrost_wait_bo {
> };
>
> #define PANFROST_BO_NOEXEC 1
> +#define PANFROST_BO_HEAP 2
>
> /**
> * struct drm_panfrost_create_bo - ioctl argument for creating Panfrost BOs.
>
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