[PATCH v2 02/11] mm: add device coherent vma selection for memory migration

Alex Sierra
2021-12-06T18:53:13Z

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.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
---
v2:
condition added when migrations from device coherent pages.
---
include/linux/migrate.h | 1 +
mm/migrate.c | 9 +++++++--
2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index c8077e936691..e74bb0978f6f 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -138,6 +138,7 @@ 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.c b/mm/migrate.c
index 91018880dc7f..0367f471211a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2340,8 +2340,6 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
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)) {
mpfn = MIGRATE_PFN_MIGRATE;
@@ -2349,6 +2347,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
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;
+ 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;
}
--
2.32.0