On 8/8/19 12:07 AM, Christoph Hellwig wrote:
On Wed, Aug 07, 2019 at 08:02:14AM -0700, Ralph Campbell wrote:
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: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
---
This patch is based on top of Christoph Hellwig's 9 patch series
https://lore.kernel.org/linux-mm/20190729234611.GC7171@xxxxxxxxxx/T/#u
"turn the hmm migrate_vma upside down" but without patch 9
"mm: remove the unused MIGRATE_PFN_WRITE" and adds a use for the flag.
This looks useful. I've already dropped that patch for the pending
resend.
Thanks.
static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm,
- struct vm_area_struct *vma, unsigned long addr,
- unsigned long src, dma_addr_t *dma_addr)
+ struct vm_area_struct *vma, unsigned long src,
+ dma_addr_t *dma_addr, u64 *pfn)
I'll pick up the removal of the not needed addr argument for the patch
introducing nouveau_dmem_migrate_copy_one, thanks,
static void nouveau_dmem_migrate_chunk(struct migrate_vma *args,
- struct nouveau_drm *drm, dma_addr_t *dma_addrs)
+ struct nouveau_drm *drm, 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->vma,
- addr, args->src[i], &dma_addrs[nr_dma]);
+ args->src[i], &dma_addrs[nr_dma], &pfns[i]);
Nit: I find the &pfns[i] way to pass the argument a little weird to read.
Why not "pfns + i"?
OK, will do in v2.
Should I convert to "dma_addrs + nr_dma" too?
+u64 *
+nouveau_pfns_alloc(unsigned long npages)
+{
+ struct nouveau_pfnmap_args *args;
+
+ args = kzalloc(sizeof(*args) + npages * sizeof(args->p.phys[0]),
Can we use struct_size here?
Yes, good suggestion.
+ int ret;
+
+ if (!svm)
+ return;
+
+ mutex_lock(&svm->mutex);
+ svmm = nouveau_find_svmm(svm, mm);
+ if (!svmm) {
+ mutex_unlock(&svm->mutex);
+ return;
+ }
+ mutex_unlock(&svm->mutex);
Given that nouveau_find_svmm doesn't take any kind of reference, what
gurantees svmm doesn't go away after dropping the lock?
I asked Ben and Jerome about this too.
I'm still looking into it.
@@ -44,5 +49,19 @@ static inline int nouveau_svmm_bind(struct drm_device *device, void *p,
{
return -ENOSYS;
}
+
+u64 *nouveau_pfns_alloc(unsigned long npages)
+{
+ return NULL;
+}
+
+void nouveau_pfns_free(u64 *pfns)
+{
+}
+
+void nouveau_pfns_map(struct nouveau_drm *drm, struct mm_struct *mm,
+ unsigned long addr, u64 *pfns, unsigned long npages)
+{
+}
#endif /* IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM) */
nouveau_dmem.c and nouveau_svm.c are both built conditional on
CONFIG_DRM_NOUVEAU_SVM, so there is no need for stubs here.
Good point. I'll remove them in v2.
