[PATCH 16/16] nouveau: support THP migration to private memory

From: Ralph Campbell
Date: Fri Jun 19 2020 - 17:58:52 EST

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Add support for migrating transparent huge pages to and from device
private memory.

Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_dmem.c | 171 +++++++++++++++++--------
drivers/gpu/drm/nouveau/nouveau_svm.c | 11 +-
drivers/gpu/drm/nouveau/nouveau_svm.h | 3 +-
3 files changed, 127 insertions(+), 58 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index f6a806ba3caa..e8c4c0bc78ae 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -46,6 +46,7 @@
*/
#define DMEM_CHUNK_SIZE (2UL << 20)
#define DMEM_CHUNK_NPAGES (DMEM_CHUNK_SIZE >> PAGE_SHIFT)
+#define PMD_ORDER (PMD_SHIFT - PAGE_SHIFT)

enum nouveau_aper {
NOUVEAU_APER_VIRT,
@@ -53,7 +54,7 @@ enum nouveau_aper {
NOUVEAU_APER_HOST,
};

-typedef int (*nouveau_migrate_copy_t)(struct nouveau_drm *drm, u64 npages,
+typedef int (*nouveau_migrate_copy_t)(struct nouveau_drm *drm, u32 length,
enum nouveau_aper, u64 dst_addr,
enum nouveau_aper, u64 src_addr);
typedef int (*nouveau_clear_page_t)(struct nouveau_drm *drm, u32 length,
@@ -79,6 +80,7 @@ struct nouveau_dmem {
struct list_head chunks;
struct mutex mutex;
struct page *free_pages;
+ struct page *free_huge_pages;
spinlock_t lock;
};

@@ -109,8 +111,13 @@ static void nouveau_dmem_page_free(struct page *page)
struct nouveau_dmem *dmem = chunk->drm->dmem;

spin_lock(&dmem->lock);
- page->zone_device_data = dmem->free_pages;
- dmem->free_pages = page;
+ if (PageHuge(page)) {
+ page->zone_device_data = dmem->free_huge_pages;
+ dmem->free_huge_pages = page;
+ } else {
+ page->zone_device_data = dmem->free_pages;
+ dmem->free_pages = page;
+ }

WARN_ON(!chunk->callocated);
chunk->callocated--;
@@ -136,33 +143,41 @@ static void nouveau_dmem_fence_done(struct nouveau_fence **fence)

static vm_fault_t nouveau_dmem_fault_copy_one(struct nouveau_drm *drm,
struct vm_fault *vmf, struct migrate_vma *args,
- dma_addr_t *dma_addr)
+ dma_addr_t *dma_addr, size_t *sizep)
{
struct device *dev = drm->dev->dev;
struct page *dpage, *spage;
+ unsigned int order;

spage = migrate_pfn_to_page(args->src[0]);
if (!spage || !(args->src[0] & MIGRATE_PFN_MIGRATE))
return 0;

- dpage = alloc_page_vma(GFP_HIGHUSER, vmf->vma, vmf->address);
+ order = compound_order(spage);
+ if (order)
+ dpage = alloc_transhugepage(vmf->vma, vmf->address);
+ else
+ dpage = alloc_page_vma(GFP_HIGHUSER, vmf->vma, vmf->address);
if (!dpage)
return VM_FAULT_SIGBUS;
+ WARN_ON_ONCE(order != compound_order(dpage));
lock_page(dpage);

- *dma_addr = dma_map_page(dev, dpage, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ *sizep = page_size(dpage);
+ *dma_addr = dma_map_page(dev, dpage, 0, *sizep, DMA_BIDIRECTIONAL);
if (dma_mapping_error(dev, *dma_addr))
goto error_free_page;

- if (drm->dmem->migrate.copy_func(drm, 1, NOUVEAU_APER_HOST, *dma_addr,
- NOUVEAU_APER_VRAM, nouveau_dmem_page_addr(spage)))
+ if (drm->dmem->migrate.copy_func(drm, page_size(spage),
+ NOUVEAU_APER_HOST, *dma_addr, NOUVEAU_APER_VRAM,
+ nouveau_dmem_page_addr(spage)))
goto error_dma_unmap;

args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
return 0;

error_dma_unmap:
- dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_unmap_page(dev, *dma_addr, page_size(dpage), DMA_BIDIRECTIONAL);
error_free_page:
__free_page(dpage);
return VM_FAULT_SIGBUS;
@@ -173,8 +188,11 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
struct nouveau_drm *drm = page_to_drm(vmf->page);
struct nouveau_dmem *dmem = drm->dmem;
struct nouveau_fence *fence;
+ struct page *page;
+ unsigned int order;
unsigned long src = 0, dst = 0;
dma_addr_t dma_addr = 0;
+ size_t size = 0;
vm_fault_t ret;
struct migrate_vma args = {
.vma = vmf->vma,
@@ -185,26 +203,52 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
.src_owner = drm->dev,
};

+ /*
+ * If the page was migrated to the GPU as a huge page, migrate it
+ * back the same way.
+ * FIXME If there is thrashing, maybe we should migrate one page.
+ */
+ page = compound_head(vmf->page);
+ order = compound_order(page);
+ if (order) {
+ args.start &= PAGE_MASK << order;
+ args.end = args.start + (PAGE_SIZE << order);
+ args.src = kcalloc(1U << order, sizeof(*args.src), GFP_KERNEL);
+ if (!args.src)
+ return VM_FAULT_OOM;
+ args.dst = kcalloc(1U << order, sizeof(*args.dst), GFP_KERNEL);
+ if (!args.dst) {
+ ret = VM_FAULT_OOM;
+ goto error_src;
+ }
+ }
+
/*
* FIXME what we really want is to find some heuristic to migrate more
* than just one page on CPU fault. When such fault happens it is very
* likely that more surrounding page will CPU fault too.
*/
- if (migrate_vma_setup(&args) < 0)
- return VM_FAULT_SIGBUS;
- if (!args.cpages)
- return 0;
+ if (migrate_vma_setup(&args) < 0) {
+ ret = VM_FAULT_SIGBUS;
+ goto error_dst;
+ }

- ret = nouveau_dmem_fault_copy_one(drm, vmf, &args, &dma_addr);
- if (ret || dst == 0)
+ ret = nouveau_dmem_fault_copy_one(drm, vmf, &args, &dma_addr, &size);
+ if (ret)
goto done;

nouveau_fence_new(dmem->migrate.chan, false, &fence);
migrate_vma_pages(&args);
nouveau_dmem_fence_done(&fence);
- dma_unmap_page(drm->dev->dev, dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_unmap_page(drm->dev->dev, dma_addr, size, DMA_BIDIRECTIONAL);
done:
migrate_vma_finalize(&args);
+error_dst:
+ if (args.dst != &dst)
+ kfree(args.dst);
+error_src:
+ if (args.src != &src)
+ kfree(args.src);
return ret;
}

@@ -213,8 +257,8 @@ static const struct dev_pagemap_ops nouveau_dmem_pagemap_ops = {
.migrate_to_ram = nouveau_dmem_migrate_to_ram,
};

-static int
-nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage)
+static int nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, bool is_huge,
+ struct page **ppage)
{
struct nouveau_dmem_chunk *chunk;
struct resource *res;
@@ -266,16 +310,20 @@ nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage)
pfn_first = chunk->pagemap.res.start >> PAGE_SHIFT;
page = pfn_to_page(pfn_first);
spin_lock(&drm->dmem->lock);
- for (i = 0; i < DMEM_CHUNK_NPAGES - 1; ++i, ++page) {
- page->zone_device_data = drm->dmem->free_pages;
- drm->dmem->free_pages = page;
- }
+ if (is_huge)
+ prep_compound_page(page, PMD_ORDER);
+ else
+ for (i = 0; i < DMEM_CHUNK_NPAGES - 1; ++i, ++page) {
+ page->zone_device_data = drm->dmem->free_pages;
+ drm->dmem->free_pages = page;
+ }
*ppage = page;
chunk->callocated++;
spin_unlock(&drm->dmem->lock);

- NV_INFO(drm, "DMEM: registered %ldMB of device memory\n",
- DMEM_CHUNK_SIZE >> 20);
+ NV_INFO(drm, "DMEM: registered %ldMB of %sdevice memory %lx %lx\n",
+ DMEM_CHUNK_SIZE >> 20, is_huge ? "huge " : "", pfn_first,
+ nouveau_dmem_page_addr(page));

return 0;

@@ -293,14 +341,20 @@ nouveau_dmem_chunk_alloc(struct nouveau_drm *drm, struct page **ppage)
}

static struct page *
-nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm)
+nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm, bool is_huge)
{
struct nouveau_dmem_chunk *chunk;
struct page *page = NULL;
int ret;

spin_lock(&drm->dmem->lock);
- if (drm->dmem->free_pages) {
+ if (is_huge && drm->dmem->free_huge_pages) {
+ page = drm->dmem->free_huge_pages;
+ drm->dmem->free_huge_pages = page->zone_device_data;
+ chunk = nouveau_page_to_chunk(page);
+ chunk->callocated++;
+ spin_unlock(&drm->dmem->lock);
+ } else if (!is_huge && drm->dmem->free_pages) {
page = drm->dmem->free_pages;
drm->dmem->free_pages = page->zone_device_data;
chunk = nouveau_page_to_chunk(page);
@@ -308,7 +362,7 @@ nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm)
spin_unlock(&drm->dmem->lock);
} else {
spin_unlock(&drm->dmem->lock);
- ret = nouveau_dmem_chunk_alloc(drm, &page);
+ ret = nouveau_dmem_chunk_alloc(drm, is_huge, &page);
if (ret)
return NULL;
}
@@ -381,19 +435,18 @@ nouveau_dmem_fini(struct nouveau_drm *drm)
}

static int
-nvc0b5_migrate_copy(struct nouveau_drm *drm, u64 npages,
+nvc0b5_migrate_copy(struct nouveau_drm *drm, u32 length,
enum nouveau_aper dst_aper, u64 dst_addr,
enum nouveau_aper src_aper, u64 src_addr)
{
struct nouveau_channel *chan = drm->dmem->migrate.chan;
- u32 launch_dma = (1 << 9) /* MULTI_LINE_ENABLE. */ |
- (1 << 8) /* DST_MEMORY_LAYOUT_PITCH. */ |
+ u32 launch_dma = (1 << 8) /* DST_MEMORY_LAYOUT_PITCH. */ |
(1 << 7) /* SRC_MEMORY_LAYOUT_PITCH. */ |
(1 << 2) /* FLUSH_ENABLE_TRUE. */ |
(2 << 0) /* DATA_TRANSFER_TYPE_NON_PIPELINED. */;
int ret;

- ret = RING_SPACE(chan, 13);
+ ret = RING_SPACE(chan, 11);
if (ret)
return ret;

@@ -425,17 +478,15 @@ nvc0b5_migrate_copy(struct nouveau_drm *drm, u64 npages,
launch_dma |= 0x00002000; /* DST_TYPE_PHYSICAL. */
}

- BEGIN_NVC0(chan, NvSubCopy, 0x0400, 8);
- OUT_RING (chan, upper_32_bits(src_addr));
- OUT_RING (chan, lower_32_bits(src_addr));
- OUT_RING (chan, upper_32_bits(dst_addr));
- OUT_RING (chan, lower_32_bits(dst_addr));
- OUT_RING (chan, PAGE_SIZE);
- OUT_RING (chan, PAGE_SIZE);
- OUT_RING (chan, PAGE_SIZE);
- OUT_RING (chan, npages);
+ BEGIN_NVC0(chan, NvSubCopy, 0x0400, 4);
+ OUT_RING(chan, upper_32_bits(src_addr));
+ OUT_RING(chan, lower_32_bits(src_addr));
+ OUT_RING(chan, upper_32_bits(dst_addr));
+ OUT_RING(chan, lower_32_bits(dst_addr));
+ BEGIN_NVC0(chan, NvSubCopy, 0x0418, 1);
+ OUT_RING(chan, length);
BEGIN_NVC0(chan, NvSubCopy, 0x0300, 1);
- OUT_RING (chan, launch_dma);
+ OUT_RING(chan, launch_dma);
return 0;
}

@@ -535,6 +586,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
struct device *dev = drm->dev->dev;
struct page *dpage, *spage;
unsigned long paddr;
+ unsigned long dst;

spage = migrate_pfn_to_page(src);
if (!(src & MIGRATE_PFN_MIGRATE))
@@ -546,7 +598,8 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
goto done;
}

- dpage = nouveau_dmem_page_alloc_locked(drm);
+ dpage = nouveau_dmem_page_alloc_locked(drm,
+ src & MIGRATE_PFN_COMPOUND);
if (!dpage)
goto out;

@@ -556,7 +609,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
DMA_BIDIRECTIONAL);
if (dma_mapping_error(dev, *dma_addr))
goto out_free_page;
- if (drm->dmem->migrate.copy_func(drm, 1,
+ if (drm->dmem->migrate.copy_func(drm, page_size(spage),
NOUVEAU_APER_VRAM, paddr, NOUVEAU_APER_HOST, *dma_addr))
goto out_dma_unmap;
} else {
@@ -571,10 +624,13 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
((paddr >> PAGE_SHIFT) << NVIF_VMM_PFNMAP_V0_ADDR_SHIFT);
if (src & MIGRATE_PFN_WRITE)
*pfn |= NVIF_VMM_PFNMAP_V0_W;
- return migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ if (PageHead(dpage))
+ dst |= MIGRATE_PFN_COMPOUND;
+ return dst;

out_dma_unmap:
- dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ dma_unmap_page(dev, *dma_addr, page_size(spage), DMA_BIDIRECTIONAL);
out_free_page:
nouveau_dmem_page_free_locked(drm, dpage);
out:
@@ -588,24 +644,30 @@ static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
{
struct nouveau_fence *fence;
unsigned long addr = args->start, nr_dma = 0, i;
+ unsigned int page_shift = PAGE_SHIFT;

for (i = 0; addr < args->end; i++) {
args->dst[i] = nouveau_dmem_migrate_copy_one(drm, args->src[i],
dma_addrs + nr_dma, pfns + i);
if (!dma_mapping_error(drm->dev->dev, dma_addrs[nr_dma]))
nr_dma++;
+ if (args->dst[i] & MIGRATE_PFN_COMPOUND) {
+ page_shift = PMD_SHIFT;
+ i++;
+ break;
+ }
addr += PAGE_SIZE;
}

nouveau_fence_new(drm->dmem->migrate.chan, false, &fence);
migrate_vma_pages(args);
nouveau_dmem_fence_done(&fence);
- nouveau_pfns_map(svmm, args->vma->vm_mm, args->start, pfns, i);
+ nouveau_pfns_map(svmm, args->vma->vm_mm, args->start, pfns, i,
+ page_shift);

- while (nr_dma--) {
- dma_unmap_page(drm->dev->dev, dma_addrs[nr_dma], PAGE_SIZE,
- DMA_BIDIRECTIONAL);
- }
+ while (nr_dma)
+ dma_unmap_page(drm->dev->dev, dma_addrs[--nr_dma],
+ 1UL << page_shift, DMA_BIDIRECTIONAL);
migrate_vma_finalize(args);
}

@@ -617,7 +679,7 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
unsigned long end)
{
unsigned long npages = (end - start) >> PAGE_SHIFT;
- unsigned long max = min(SG_MAX_SINGLE_ALLOC, npages);
+ unsigned long max = min(1UL << PMD_ORDER, npages);
dma_addr_t *dma_addrs;
struct migrate_vma args = {
.vma = vma,
@@ -646,8 +708,10 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
if (!pfns)
goto out_free_dma;

- for (i = 0; i < npages; i += max) {
- args.end = start + (max << PAGE_SHIFT);
+ for (; args.start < end; args.start = args.end) {
+ args.end = ALIGN(args.start, PMD_SIZE);
+ if (args.start == args.end)
+ args.end = min(end, args.start + PMD_SIZE);
ret = migrate_vma_setup(&args);
if (ret)
goto out_free_pfns;
@@ -655,7 +719,6 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
if (args.cpages)
nouveau_dmem_migrate_chunk(drm, svmm, &args, dma_addrs,
pfns);
- args.start = args.end;
}

ret = 0;
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index a27625f3c5f9..f386a9318190 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -684,7 +684,6 @@ nouveau_svm_fault(struct nvif_notify *notify)
nouveau_svm_fault_cancel_fault(svm, buffer->fault[fi]);
continue;
}
- SVMM_DBG(svmm, "addr %016llx", buffer->fault[fi]->addr);

/* We try and group handling of faults within a small
* window into a single update.
@@ -736,6 +735,10 @@ nouveau_svm_fault(struct nvif_notify *notify)
}
mmput(mm);

+ SVMM_DBG(svmm, "addr %llx %s %c", buffer->fault[fi]->addr,
+ args.phys[0] & NVIF_VMM_PFNMAP_V0_VRAM ?
+ "vram" : "sysmem",
+ args.i.p.size > PAGE_SIZE ? 'H' : 'N');
limit = args.i.p.addr + args.i.p.size;
for (fn = fi; ++fn < buffer->fault_nr; ) {
/* It's okay to skip over duplicate addresses from the
@@ -807,13 +810,15 @@ nouveau_pfns_free(u64 *pfns)

void
nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
- unsigned long addr, u64 *pfns, unsigned long npages)
+ unsigned long addr, u64 *pfns, unsigned long npages,
+ unsigned int page_shift)
{
struct nouveau_pfnmap_args *args = nouveau_pfns_to_args(pfns);
int ret;

args->p.addr = addr;
- args->p.size = npages << PAGE_SHIFT;
+ args->p.page = page_shift;
+ args->p.size = npages << args->p.page;

mutex_lock(&svmm->mutex);

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.h b/drivers/gpu/drm/nouveau/nouveau_svm.h
index f0fcd1b72e8b..ba5927e445ad 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.h
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.h
@@ -22,7 +22,8 @@ int nouveau_svmm_bind(struct drm_device *, void *, struct drm_file *);
u64 *nouveau_pfns_alloc(unsigned long npages);
void nouveau_pfns_free(u64 *pfns);
void nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
- unsigned long addr, u64 *pfns, unsigned long npages);
+ unsigned long addr, u64 *pfns, unsigned long npages,
+ unsigned int page_shift);
#else /* IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM) */
static inline void nouveau_svm_init(struct nouveau_drm *drm) {}
static inline void nouveau_svm_fini(struct nouveau_drm *drm) {}
--
2.20.1

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