On 3/3/20 4:42 AM, Jason Gunthorpe wrote:
On Mon, Mar 02, 2020 at 05:00:23PM -0800, 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>
---
Originally this patch was targeted for Jason's rdma tree since other HMM
related changes were queued there. Now that those have been merged, this
patch just contains changes to nouveau so it could go through any tree.
I guess Ben Skeggs' tree would be appropriate.
Yep
+static inline struct nouveau_pfnmap_args *
+nouveau_pfns_to_args(void *pfns)
don't use static inline inside C files
OK.
+{
+ struct nvif_vmm_pfnmap_v0 *p =
+ container_of(pfns, struct nvif_vmm_pfnmap_v0, phys);
+
+ return container_of(p, struct nouveau_pfnmap_args, p);
And this should just be
return container_of(pfns, struct nouveau_pfnmap_args, p.phys);
Much simpler, thanks.
+static struct nouveau_svmm *
+nouveau_find_svmm(struct nouveau_svm *svm, struct mm_struct *mm)
+{
+ struct nouveau_ivmm *ivmm;
+
+ list_for_each_entry(ivmm, &svm->inst, head) {
+ if (ivmm->svmm->notifier.mm == mm)
+ return ivmm->svmm;
+ }
+ return NULL;
+}
Is this re-implementing mmu_notifier_get() ?
Jason
Not quite. This is being called from an ioctl() call on the GPU device
file which calls nouveau_svmm_bind() which locks mmap_sem for reading,
walks the vmas for the address range given in the ioctl() data, and migrates
the pages to the GPU memory.
mmu_notifier_get() would try to lock mmap_sem for writing so that would deadlock.
But it is similar in that the GPU specific process context (nouveau_svmm) needs
to be found for the given ioctl caller.
If find_get_mmu_notifier() was exported, I think that could work.
Now that I look at this again, there is an easier way to find the svmm and I see
some other bugs that need fixing. I'll post a v3 as soon as I get those written
and tested.
Thanks for the review.
