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@nvidia.com Cc: Christoph Hellwig hch@lst.de Cc: Jason Gunthorpe jgg@mellanox.com Cc: "Jérôme Glisse" jglisse@redhat.com Cc: Ben Skeggs bskeggs@redhat.com
This patch is based on top of Christoph Hellwig's 9 patch series https://lore.kernel.org/linux-mm/20190729234611.GC7171@redhat.com/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.