mm: add device coherent vma selection for memory migration

This case is used to migrate pages from device memory, back to system
memory.  Device coherent type memory is cache coherent from device and CPU
point of view.

Link: https://lkml.kernel.org/r/20220715150521.18165-6-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 069a89e..b84908d 100644 (file)
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -148,6 +148,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn)
 enum migrate_vma_direction {
        MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
        MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
+       MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2,
 };
 
 struct migrate_vma {

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index a4847ad..18bc648 100644 (file)
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -148,15 +148,21 @@ again:
                        if (is_writable_device_private_entry(entry))
                                mpfn |= MIGRATE_PFN_WRITE;
                } else {
-                       if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
-                               goto next;
                        pfn = pte_pfn(pte);
-                       if (is_zero_pfn(pfn)) {
+                       if (is_zero_pfn(pfn) &&
+                           (migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) {
                                mpfn = MIGRATE_PFN_MIGRATE;
                                migrate->cpages++;
                                goto next;
                        }
                        page = vm_normal_page(migrate->vma, addr, pte);
+                       if (page && !is_zone_device_page(page) &&
+                           !(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
+                               goto next;
+                       else if (page && is_device_coherent_page(page) &&
+                           (!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_COHERENT) ||
+                            page->pgmap->owner != migrate->pgmap_owner))
+                               goto next;
                        mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE;
                        mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0;
                }