[PATCH v3 4/4] nouveau/hmm: map pages after migration

From: Ralph Campbell
Date: Tue Mar 03 2020 - 19:14:20 EST

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When memory is migrated to the GPU, it is likely to be accessed by GPU
code soon afterwards. Instead of waiting for a GPU fault, map the
migrated memory into the GPU page tables with the same access permissions
as the source CPU page table entries. This preserves copy on write
semantics.

Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: "JÃrÃme Glisse" <jglisse@xxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_dmem.c | 46 +++++++++++++-------
drivers/gpu/drm/nouveau/nouveau_dmem.h | 2 +
drivers/gpu/drm/nouveau/nouveau_svm.c | 59 +++++++++++++++++++++++++-
drivers/gpu/drm/nouveau/nouveau_svm.h | 5 +++
4 files changed, 95 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 0ad5d87b5a8e..981c05a2a6ca 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -25,11 +25,13 @@
#include "nouveau_dma.h"
#include "nouveau_mem.h"
#include "nouveau_bo.h"
+#include "nouveau_svm.h"

#include <nvif/class.h>
#include <nvif/object.h>
#include <nvif/if500b.h>
#include <nvif/if900b.h>
+#include <nvif/if000c.h>

#include <linux/sched/mm.h>
#include <linux/hmm.h>
@@ -558,10 +560,11 @@ nouveau_dmem_init(struct nouveau_drm *drm)
}

static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
- unsigned long src, dma_addr_t *dma_addr)
+ unsigned long src, dma_addr_t *dma_addr, u64 *pfn)
{
struct device *dev = drm->dev->dev;
struct page *dpage, *spage;
+ unsigned long paddr;

spage = migrate_pfn_to_page(src);
if (!spage || !(src & MIGRATE_PFN_MIGRATE))
@@ -569,17 +572,21 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,

dpage = nouveau_dmem_page_alloc_locked(drm);
if (!dpage)
- return 0;
+ goto out;

*dma_addr = dma_map_page(dev, spage, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
if (dma_mapping_error(dev, *dma_addr))
goto out_free_page;

+ paddr = nouveau_dmem_page_addr(dpage);
if (drm->dmem->migrate.copy_func(drm, 1, NOUVEAU_APER_VRAM,
- nouveau_dmem_page_addr(dpage), NOUVEAU_APER_HOST,
- *dma_addr))
+ paddr, NOUVEAU_APER_HOST, *dma_addr))
goto out_dma_unmap;

+ *pfn = NVIF_VMM_PFNMAP_V0_V | NVIF_VMM_PFNMAP_V0_VRAM |
+ ((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;

out_dma_unmap:
@@ -587,18 +594,20 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
out_free_page:
nouveau_dmem_page_free_locked(drm, dpage);
out:
+ *pfn = NVIF_VMM_PFNMAP_V0_NONE;
return 0;
}

static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
- struct migrate_vma *args, dma_addr_t *dma_addrs)
+ struct nouveau_svmm *svmm, struct migrate_vma *args,
+ dma_addr_t *dma_addrs, u64 *pfns)
{
struct nouveau_fence *fence;
unsigned long addr = args->start, nr_dma = 0, i;

for (i = 0; addr < args->end; i++) {
args->dst[i] = nouveau_dmem_migrate_copy_one(drm, args->src[i],
- dma_addrs + nr_dma);
+ dma_addrs + nr_dma, pfns + i);
if (args->dst[i])
nr_dma++;
addr += PAGE_SIZE;
@@ -607,20 +616,18 @@ static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
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);

while (nr_dma--) {
dma_unmap_page(drm->dev->dev, dma_addrs[nr_dma], PAGE_SIZE,
DMA_BIDIRECTIONAL);
}
- /*
- * FIXME optimization: update GPU page table to point to newly migrated
- * memory.
- */
migrate_vma_finalize(args);
}

int
nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
+ struct nouveau_svmm *svmm,
struct vm_area_struct *vma,
unsigned long start,
unsigned long end)
@@ -632,7 +639,8 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
.vma = vma,
.start = start,
};
- unsigned long c, i;
+ unsigned long i;
+ u64 *pfns;
int ret = -ENOMEM;

args.src = kcalloc(max, sizeof(*args.src), GFP_KERNEL);
@@ -646,19 +654,25 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
if (!dma_addrs)
goto out_free_dst;

- for (i = 0; i < npages; i += c) {
- c = min(SG_MAX_SINGLE_ALLOC, npages);
- args.end = start + (c << PAGE_SHIFT);
+ pfns = nouveau_pfns_alloc(max);
+ if (!pfns)
+ goto out_free_dma;
+
+ for (i = 0; i < npages; i += max) {
+ args.end = start + (max << PAGE_SHIFT);
ret = migrate_vma_setup(&args);
if (ret)
- goto out_free_dma;
+ goto out_free_pfns;

if (args.cpages)
- nouveau_dmem_migrate_chunk(drm, &args, dma_addrs);
+ nouveau_dmem_migrate_chunk(drm, svmm, &args, dma_addrs,
+ pfns);
args.start = args.end;
}

ret = 0;
+out_free_pfns:
+ nouveau_pfns_free(pfns);
out_free_dma:
kfree(dma_addrs);
out_free_dst:
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.h b/drivers/gpu/drm/nouveau/nouveau_dmem.h
index 92394be5d649..3e03d9629a38 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.h
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.h
@@ -25,6 +25,7 @@
struct drm_device;
struct drm_file;
struct nouveau_drm;
+struct nouveau_svmm;
struct hmm_range;

#if IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM)
@@ -34,6 +35,7 @@ void nouveau_dmem_suspend(struct nouveau_drm *);
void nouveau_dmem_resume(struct nouveau_drm *);

int nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
+ struct nouveau_svmm *svmm,
struct vm_area_struct *vma,
unsigned long start,
unsigned long end);
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 8dfa5cb74826..d33ae94c28ba 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -70,6 +70,12 @@ struct nouveau_svm {
#define SVM_DBG(s,f,a...) NV_DEBUG((s)->drm, "svm: "f"\n", ##a)
#define SVM_ERR(s,f,a...) NV_WARN((s)->drm, "svm: "f"\n", ##a)

+struct nouveau_pfnmap_args {
+ struct nvif_ioctl_v0 i;
+ struct nvif_ioctl_mthd_v0 m;
+ struct nvif_vmm_pfnmap_v0 p;
+};
+
struct nouveau_ivmm {
struct nouveau_svmm *svmm;
u64 inst;
@@ -187,7 +193,8 @@ nouveau_svmm_bind(struct drm_device *dev, void *data,
addr = max(addr, vma->vm_start);
next = min(vma->vm_end, end);
/* This is a best effort so we ignore errors */
- nouveau_dmem_migrate_vma(cli->drm, vma, addr, next);
+ nouveau_dmem_migrate_vma(cli->drm, cli->svm.svmm, vma, addr,
+ next);
addr = next;
}

@@ -785,6 +792,56 @@ nouveau_svm_fault(struct nvif_notify *notify)
return NVIF_NOTIFY_KEEP;
}

+static struct nouveau_pfnmap_args *
+nouveau_pfns_to_args(void *pfns)
+{
+ return container_of(pfns, struct nouveau_pfnmap_args, p.phys);
+}
+
+u64 *
+nouveau_pfns_alloc(unsigned long npages)
+{
+ struct nouveau_pfnmap_args *args;
+
+ args = kzalloc(struct_size(args, p.phys, npages), GFP_KERNEL);
+ if (!args)
+ return NULL;
+
+ args->i.type = NVIF_IOCTL_V0_MTHD;
+ args->m.method = NVIF_VMM_V0_PFNMAP;
+ args->p.page = PAGE_SHIFT;
+
+ return args->p.phys;
+}
+
+void
+nouveau_pfns_free(u64 *pfns)
+{
+ struct nouveau_pfnmap_args *args = nouveau_pfns_to_args(pfns);
+
+ kfree(args);
+}
+
+void
+nouveau_pfns_map(struct nouveau_svmm *svmm, struct mm_struct *mm,
+ unsigned long addr, u64 *pfns, unsigned long npages)
+{
+ struct nouveau_pfnmap_args *args = nouveau_pfns_to_args(pfns);
+ int ret;
+
+ args->p.addr = addr;
+ args->p.size = npages << PAGE_SHIFT;
+
+ mutex_lock(&svmm->mutex);
+
+ svmm->vmm->vmm.object.client->super = true;
+ ret = nvif_object_ioctl(&svmm->vmm->vmm.object, args, sizeof(*args) +
+ npages * sizeof(args->p.phys[0]), NULL);
+ svmm->vmm->vmm.object.client->super = false;
+
+ mutex_unlock(&svmm->mutex);
+}
+
static void
nouveau_svm_fault_buffer_fini(struct nouveau_svm *svm, int id)
{
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.h b/drivers/gpu/drm/nouveau/nouveau_svm.h
index e839d8189461..f0fcd1b72e8b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.h
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.h
@@ -18,6 +18,11 @@ void nouveau_svmm_fini(struct nouveau_svmm **);
int nouveau_svmm_join(struct nouveau_svmm *, u64 inst);
void nouveau_svmm_part(struct nouveau_svmm *, u64 inst);
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);
#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

Next message: Ralph Campbell: "[PATCH v3 2/4] nouveau/hmm: check for SVM initialized before migrating"
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Next in thread: Ralph Campbell: "[PATCH v3 2/4] nouveau/hmm: check for SVM initialized before migrating"
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