[PATCH v4 00/13] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping

[PATCH v4 00/13] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping

[Alex Sierra]

This is our MEMORY_DEVICE_COHERENT patch series rebased and updated
for current 5.18.0

Changes since the last version:
- Fixed problems with migration during long-term pinning in
get_user_pages
- Open coded vm_normal_lru_pages as suggested in previous code review
- Update hmm_gup_test with more get_user_pages calls, include
hmm_cow_in_device in hmm-test.

This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory
owned by a device that can be mapped into CPU page tables like
MEMORY_DEVICE_GENERIC and can also be migrated like
MEMORY_DEVICE_PRIVATE.

This patch series is mostly self-contained except for a few places where
it needs to update other subsystems to handle the new memory type.

System stability and performance are not affected according to our
ongoing testing, including xfstests.

How it works: The system BIOS advertises the GPU device memory
(aka VRAM) as SPM (special purpose memory) in the UEFI system address
map.

The amdgpu driver registers the memory with devmap as
MEMORY_DEVICE_COHERENT using devm_memremap_pages. The initial user for
this hardware page migration capability is the Frontier supercomputer
project. This functionality is not AMD-specific. We expect other GPU
vendors to find this functionality useful, and possibly other hardware
types in the future.

Our test nodes in the lab are similar to the Frontier configuration,
with .5 TB of system memory plus 256 GB of device memory split across
4 GPUs, all in a single coherent address space. Page migration is
expected to improve application efficiency significantly. We will
report empirical results as they become available.

Coherent device type pages at gup are now migrated back to system
memory if they are being pinned long-term (FOLL_LONGTERM). The reason
is, that long-term pinning would interfere with the device memory
manager owning the device-coherent pages (e.g. evictions in TTM).
These series incorporate Alistair Popple patches to do this
migration from pin_user_pages() calls. hmm_gup_test has been added to
hmm-test to test different get user pages calls.

This series includes handling of device-managed anonymous pages
returned by vm_normal_pages. Although they behave like normal pages
for purposes of mapping in CPU page tables and for COW, they do not
support LRU lists, NUMA migration or THP.

We also introduced a FOLL_LRU flag that adds the same behaviour to
follow_page and related APIs, to allow callers to specify that they
expect to put pages on an LRU list.

v2:
- Rebase to latest 5.18-rc7.
- Drop patch "mm: add device coherent checker to remove migration pte"
and modify try_to_migrate_one, to let DEVICE_COHERENT pages fall
through to normal page path. Based on Alistair Popple's comment.
- Fix comment formatting.
- Reword comment in vm_normal_page about pte_devmap().
- Merge "drm/amdkfd: coherent type as sys mem on migration to ram" to
"drm/amdkfd: add SPM support for SVM".

v3:
- Rebase to latest 5.18.0.
- Patch "mm: handling Non-LRU pages returned by vm_normal_pages"
reordered.
- Add WARN_ON_ONCE for thp device coherent case.

v4:
- Rebase to latest 5.18.0
- Fix consitency between pages with FOLL_LRU flag set and pte_devmap
at follow_page_pte.

Alex Sierra (11):
  mm: add zone device coherent type memory support
  mm: handling Non-LRU pages returned by vm_normal_pages
  mm: add device coherent vma selection for memory migration
  drm/amdkfd: add SPM support for SVM
  lib: test_hmm add ioctl to get zone device type
  lib: test_hmm add module param for zone device type
  lib: add support for device coherent type in test_hmm
  tools: update hmm-test to support device coherent type
  tools: update test_hmm script to support SP config
  tools: add hmm gup tests for device coherent type
  tools: add selftests to hmm for COW in device memory

Alistair Popple (2):
  mm: remove the vma check in migrate_vma_setup()
  mm/gup: migrate device coherent pages when pinning instead of failing

 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c |  34 ++-
 fs/proc/task_mmu.c                       |   2 +-
 include/linux/memremap.h                 |  19 ++
 include/linux/migrate.h                  |   1 +
 include/linux/mm.h                       |   3 +-
 lib/test_hmm.c                           | 349 +++++++++++++++++------
 lib/test_hmm_uapi.h                      |  22 +-
 mm/gup.c                                 |  53 +++-
 mm/huge_memory.c                         |   2 +-
 mm/internal.h                            |   1 +
 mm/khugepaged.c                          |   9 +-
 mm/ksm.c                                 |   6 +-
 mm/madvise.c                             |   4 +-
 mm/memcontrol.c                          |   7 +-
 mm/memory-failure.c                      |   8 +-
 mm/memory.c                              |   9 +-
 mm/mempolicy.c                           |   2 +-
 mm/memremap.c                            |  10 +
 mm/migrate.c                             |   4 +-
 mm/migrate_device.c                      | 115 ++++++--
 mm/mlock.c                               |   2 +-
 mm/mprotect.c                            |   2 +-
 mm/rmap.c                                |   5 +-
 tools/testing/selftests/vm/hmm-tests.c   | 308 ++++++++++++++++++--
 tools/testing/selftests/vm/test_hmm.sh   |  24 +-
 25 files changed, 817 insertions(+), 184 deletions(-)

-- 
2.32.0

[PATCH v4 00/13] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping

[Alex Sierra]

This is our MEMORY_DEVICE_COHERENT patch series rebased and updated
for current 5.18.0

Changes since the last version:
- Fixed problems with migration during long-term pinning in
get_user_pages
- Open coded vm_normal_lru_pages as suggested in previous code review
- Update hmm_gup_test with more get_user_pages calls, include
hmm_cow_in_device in hmm-test.

This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory
owned by a device that can be mapped into CPU page tables like
MEMORY_DEVICE_GENERIC and can also be migrated like
MEMORY_DEVICE_PRIVATE.

This patch series is mostly self-contained except for a few places where
it needs to update other subsystems to handle the new memory type.

System stability and performance are not affected according to our
ongoing testing, including xfstests.

How it works: The system BIOS advertises the GPU device memory
(aka VRAM) as SPM (special purpose memory) in the UEFI system address
map.

The amdgpu driver registers the memory with devmap as
MEMORY_DEVICE_COHERENT using devm_memremap_pages. The initial user for
this hardware page migration capability is the Frontier supercomputer
project. This functionality is not AMD-specific. We expect other GPU
vendors to find this functionality useful, and possibly other hardware
types in the future.

Our test nodes in the lab are similar to the Frontier configuration,
with .5 TB of system memory plus 256 GB of device memory split across
4 GPUs, all in a single coherent address space. Page migration is
expected to improve application efficiency significantly. We will
report empirical results as they become available.

Coherent device type pages at gup are now migrated back to system
memory if they are being pinned long-term (FOLL_LONGTERM). The reason
is, that long-term pinning would interfere with the device memory
manager owning the device-coherent pages (e.g. evictions in TTM).
These series incorporate Alistair Popple patches to do this
migration from pin_user_pages() calls. hmm_gup_test has been added to
hmm-test to test different get user pages calls.

This series includes handling of device-managed anonymous pages
returned by vm_normal_pages. Although they behave like normal pages
for purposes of mapping in CPU page tables and for COW, they do not
support LRU lists, NUMA migration or THP.

We also introduced a FOLL_LRU flag that adds the same behaviour to
follow_page and related APIs, to allow callers to specify that they
expect to put pages on an LRU list.

v2:
- Rebase to latest 5.18-rc7.
- Drop patch "mm: add device coherent checker to remove migration pte"
and modify try_to_migrate_one, to let DEVICE_COHERENT pages fall
through to normal page path. Based on Alistair Popple's comment.
- Fix comment formatting.
- Reword comment in vm_normal_page about pte_devmap().
- Merge "drm/amdkfd: coherent type as sys mem on migration to ram" to
"drm/amdkfd: add SPM support for SVM".

v3:
- Rebase to latest 5.18.0.
- Patch "mm: handling Non-LRU pages returned by vm_normal_pages"
reordered.
- Add WARN_ON_ONCE for thp device coherent case.

v4:
- Rebase to latest 5.18.0
- Fix consitency between pages with FOLL_LRU flag set and pte_devmap
at follow_page_pte.

Alex Sierra (11):
  mm: add zone device coherent type memory support
  mm: handling Non-LRU pages returned by vm_normal_pages
  mm: add device coherent vma selection for memory migration
  drm/amdkfd: add SPM support for SVM
  lib: test_hmm add ioctl to get zone device type
  lib: test_hmm add module param for zone device type
  lib: add support for device coherent type in test_hmm
  tools: update hmm-test to support device coherent type
  tools: update test_hmm script to support SP config
  tools: add hmm gup tests for device coherent type
  tools: add selftests to hmm for COW in device memory

Alistair Popple (2):
  mm: remove the vma check in migrate_vma_setup()
  mm/gup: migrate device coherent pages when pinning instead of failing

 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c |  34 ++-
 fs/proc/task_mmu.c                       |   2 +-
 include/linux/memremap.h                 |  19 ++
 include/linux/migrate.h                  |   1 +
 include/linux/mm.h                       |   3 +-
 lib/test_hmm.c                           | 349 +++++++++++++++++------
 lib/test_hmm_uapi.h                      |  22 +-
 mm/gup.c                                 |  53 +++-
 mm/huge_memory.c                         |   2 +-
 mm/internal.h                            |   1 +
 mm/khugepaged.c                          |   9 +-
 mm/ksm.c                                 |   6 +-
 mm/madvise.c                             |   4 +-
 mm/memcontrol.c                          |   7 +-
 mm/memory-failure.c                      |   8 +-
 mm/memory.c                              |   9 +-
 mm/mempolicy.c                           |   2 +-
 mm/memremap.c                            |  10 +
 mm/migrate.c                             |   4 +-
 mm/migrate_device.c                      | 115 ++++++--
 mm/mlock.c                               |   2 +-
 mm/mprotect.c                            |   2 +-
 mm/rmap.c                                |   5 +-
 tools/testing/selftests/vm/hmm-tests.c   | 308 ++++++++++++++++++--
 tools/testing/selftests/vm/test_hmm.sh   |  24 +-
 25 files changed, 817 insertions(+), 184 deletions(-)

-- 
2.32.0

[PATCH v4 01/13] mm: add zone device coherent type memory support

[Alex Sierra]

Device memory that is cache coherent from device and CPU point of view.
This is used on platforms that have an advanced system bus (like CAPI
or CXL). Any page of a process can be migrated to such memory. However,
no one should be allowed to pin such memory so that it can always be
evicted.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
[hch: rebased ontop of the refcount changes,
      removed is_dev_private_or_coherent_page]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/memremap.h | 19 +++++++++++++++++++
 mm/memcontrol.c          |  7 ++++---
 mm/memory-failure.c      |  8 ++++++--
 mm/memremap.c            | 10 ++++++++++
 mm/migrate_device.c      | 16 +++++++---------
 mm/rmap.c                |  5 +++--
 6 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 8af304f6b504..9f752ebed613 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -41,6 +41,13 @@ struct vmem_altmap {
  * A more complete discussion of unaddressable memory may be found in
  * include/linux/hmm.h and Documentation/vm/hmm.rst.
  *
+ * MEMORY_DEVICE_COHERENT:
+ * Device memory that is cache coherent from device and CPU point of view. This
+ * is used on platforms that have an advanced system bus (like CAPI or CXL). A
+ * driver can hotplug the device memory using ZONE_DEVICE and with that memory
+ * type. Any page of a process can be migrated to such memory. However no one
+ * should be allowed to pin such memory so that it can always be evicted.
+ *
  * MEMORY_DEVICE_FS_DAX:
  * Host memory that has similar access semantics as System RAM i.e. DMA
  * coherent and supports page pinning. In support of coordinating page
@@ -61,6 +68,7 @@ struct vmem_altmap {
 enum memory_type {
 	/* 0 is reserved to catch uninitialized type fields */
 	MEMORY_DEVICE_PRIVATE = 1,
+	MEMORY_DEVICE_COHERENT,
 	MEMORY_DEVICE_FS_DAX,
 	MEMORY_DEVICE_GENERIC,
 	MEMORY_DEVICE_PCI_P2PDMA,
@@ -143,6 +151,17 @@ static inline bool folio_is_device_private(const struct folio *folio)
 	return is_device_private_page(&folio->page);
 }
 
+static inline bool is_device_coherent_page(const struct page *page)
+{
+	return is_zone_device_page(page) &&
+		page->pgmap->type == MEMORY_DEVICE_COHERENT;
+}
+
+static inline bool folio_is_device_coherent(const struct folio *folio)
+{
+	return is_device_coherent_page(&folio->page);
+}
+
 static inline bool is_pci_p2pdma_page(const struct page *page)
 {
 	return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index abec50f31fe6..93f80d7ca148 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5665,8 +5665,8 @@ static int mem_cgroup_move_account(struct page *page,
  *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
  *     target for charge migration. if @target is not NULL, the entry is stored
  *     in target->ent.
- *   3(MC_TARGET_DEVICE): like MC_TARGET_PAGE  but page is MEMORY_DEVICE_PRIVATE
- *     (so ZONE_DEVICE page and thus not on the lru).
+ *   3(MC_TARGET_DEVICE): like MC_TARGET_PAGE  but page is device memory and
+ *   thus not on the lru.
  *     For now we such page is charge like a regular page would be as for all
  *     intent and purposes it is just special memory taking the place of a
  *     regular page.
@@ -5704,7 +5704,8 @@ static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
 		 */
 		if (page_memcg(page) == mc.from) {
 			ret = MC_TARGET_PAGE;
-			if (is_device_private_page(page))
+			if (is_device_private_page(page) ||
+			    is_device_coherent_page(page))
 				ret = MC_TARGET_DEVICE;
 			if (target)
 				target->page = page;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b85661cbdc4a..0b6a0a01ee09 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1683,12 +1683,16 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		goto unlock;
 	}
 
-	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
+	switch (pgmap->type) {
+	case MEMORY_DEVICE_PRIVATE:
+	case MEMORY_DEVICE_COHERENT:
 		/*
-		 * TODO: Handle HMM pages which may need coordination
+		 * TODO: Handle device pages which may need coordination
 		 * with device-side memory.
 		 */
 		goto unlock;
+	default:
+		break;
 	}
 
 	/*
diff --git a/mm/memremap.c b/mm/memremap.c
index 2b92e97cb25b..dbd2631b3520 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -315,6 +315,16 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 			return ERR_PTR(-EINVAL);
 		}
 		break;
+	case MEMORY_DEVICE_COHERENT:
+		if (!pgmap->ops->page_free) {
+			WARN(1, "Missing page_free method\n");
+			return ERR_PTR(-EINVAL);
+		}
+		if (!pgmap->owner) {
+			WARN(1, "Missing owner\n");
+			return ERR_PTR(-EINVAL);
+		}
+		break;
 	case MEMORY_DEVICE_FS_DAX:
 		if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
 			WARN(1, "File system DAX not supported\n");
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 5052093d0262..a4847ad65da3 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -518,7 +518,7 @@ EXPORT_SYMBOL(migrate_vma_setup);
  *     handle_pte_fault()
  *       do_anonymous_page()
  * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE
- * private page.
+ * private or coherent page.
  */
 static void migrate_vma_insert_page(struct migrate_vma *migrate,
 				    unsigned long addr,
@@ -594,11 +594,8 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 						page_to_pfn(page));
 		entry = swp_entry_to_pte(swp_entry);
 	} else {
-		/*
-		 * For now we only support migrating to un-addressable device
-		 * memory.
-		 */
-		if (is_zone_device_page(page)) {
+		if (is_zone_device_page(page) &&
+		    !is_device_coherent_page(page)) {
 			pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
 			goto abort;
 		}
@@ -701,10 +698,11 @@ void migrate_vma_pages(struct migrate_vma *migrate)
 
 		mapping = page_mapping(page);
 
-		if (is_device_private_page(newpage)) {
+		if (is_device_private_page(newpage) ||
+		    is_device_coherent_page(newpage)) {
 			/*
-			 * For now only support private anonymous when migrating
-			 * to un-addressable device memory.
+			 * For now only support anonymous memory migrating to
+			 * device private or coherent memory.
 			 */
 			if (mapping) {
 				migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
diff --git a/mm/rmap.c b/mm/rmap.c
index 5bcb334cd6f2..04fac1af870b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1957,7 +1957,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 		/* Update high watermark before we lower rss */
 		update_hiwater_rss(mm);
 
-		if (folio_is_zone_device(folio)) {
+		if (folio_is_device_private(folio)) {
 			unsigned long pfn = folio_pfn(folio);
 			swp_entry_t entry;
 			pte_t swp_pte;
@@ -2131,7 +2131,8 @@ void try_to_migrate(struct folio *folio, enum ttu_flags flags)
 					TTU_SYNC)))
 		return;
 
-	if (folio_is_zone_device(folio) && !folio_is_device_private(folio))
+	if (folio_is_zone_device(folio) &&
+	    (!folio_is_device_private(folio) && !folio_is_device_coherent(folio)))
 		return;
 
 	/*
-- 
2.32.0

[PATCH v4 01/13] mm: add zone device coherent type memory support

[Alex Sierra]

Device memory that is cache coherent from device and CPU point of view.
This is used on platforms that have an advanced system bus (like CAPI
or CXL). Any page of a process can be migrated to such memory. However,
no one should be allowed to pin such memory so that it can always be
evicted.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
[hch: rebased ontop of the refcount changes,
      removed is_dev_private_or_coherent_page]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/memremap.h | 19 +++++++++++++++++++
 mm/memcontrol.c          |  7 ++++---
 mm/memory-failure.c      |  8 ++++++--
 mm/memremap.c            | 10 ++++++++++
 mm/migrate_device.c      | 16 +++++++---------
 mm/rmap.c                |  5 +++--
 6 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 8af304f6b504..9f752ebed613 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -41,6 +41,13 @@ struct vmem_altmap {
  * A more complete discussion of unaddressable memory may be found in
  * include/linux/hmm.h and Documentation/vm/hmm.rst.
  *
+ * MEMORY_DEVICE_COHERENT:
+ * Device memory that is cache coherent from device and CPU point of view. This
+ * is used on platforms that have an advanced system bus (like CAPI or CXL). A
+ * driver can hotplug the device memory using ZONE_DEVICE and with that memory
+ * type. Any page of a process can be migrated to such memory. However no one
+ * should be allowed to pin such memory so that it can always be evicted.
+ *
  * MEMORY_DEVICE_FS_DAX:
  * Host memory that has similar access semantics as System RAM i.e. DMA
  * coherent and supports page pinning. In support of coordinating page
@@ -61,6 +68,7 @@ struct vmem_altmap {
 enum memory_type {
 	/* 0 is reserved to catch uninitialized type fields */
 	MEMORY_DEVICE_PRIVATE = 1,
+	MEMORY_DEVICE_COHERENT,
 	MEMORY_DEVICE_FS_DAX,
 	MEMORY_DEVICE_GENERIC,
 	MEMORY_DEVICE_PCI_P2PDMA,
@@ -143,6 +151,17 @@ static inline bool folio_is_device_private(const struct folio *folio)
 	return is_device_private_page(&folio->page);
 }
 
+static inline bool is_device_coherent_page(const struct page *page)
+{
+	return is_zone_device_page(page) &&
+		page->pgmap->type == MEMORY_DEVICE_COHERENT;
+}
+
+static inline bool folio_is_device_coherent(const struct folio *folio)
+{
+	return is_device_coherent_page(&folio->page);
+}
+
 static inline bool is_pci_p2pdma_page(const struct page *page)
 {
 	return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index abec50f31fe6..93f80d7ca148 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5665,8 +5665,8 @@ static int mem_cgroup_move_account(struct page *page,
  *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
  *     target for charge migration. if @target is not NULL, the entry is stored
  *     in target->ent.
- *   3(MC_TARGET_DEVICE): like MC_TARGET_PAGE  but page is MEMORY_DEVICE_PRIVATE
- *     (so ZONE_DEVICE page and thus not on the lru).
+ *   3(MC_TARGET_DEVICE): like MC_TARGET_PAGE  but page is device memory and
+ *   thus not on the lru.
  *     For now we such page is charge like a regular page would be as for all
  *     intent and purposes it is just special memory taking the place of a
  *     regular page.
@@ -5704,7 +5704,8 @@ static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
 		 */
 		if (page_memcg(page) == mc.from) {
 			ret = MC_TARGET_PAGE;
-			if (is_device_private_page(page))
+			if (is_device_private_page(page) ||
+			    is_device_coherent_page(page))
 				ret = MC_TARGET_DEVICE;
 			if (target)
 				target->page = page;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b85661cbdc4a..0b6a0a01ee09 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1683,12 +1683,16 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		goto unlock;
 	}
 
-	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
+	switch (pgmap->type) {
+	case MEMORY_DEVICE_PRIVATE:
+	case MEMORY_DEVICE_COHERENT:
 		/*
-		 * TODO: Handle HMM pages which may need coordination
+		 * TODO: Handle device pages which may need coordination
 		 * with device-side memory.
 		 */
 		goto unlock;
+	default:
+		break;
 	}
 
 	/*
diff --git a/mm/memremap.c b/mm/memremap.c
index 2b92e97cb25b..dbd2631b3520 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -315,6 +315,16 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 			return ERR_PTR(-EINVAL);
 		}
 		break;
+	case MEMORY_DEVICE_COHERENT:
+		if (!pgmap->ops->page_free) {
+			WARN(1, "Missing page_free method\n");
+			return ERR_PTR(-EINVAL);
+		}
+		if (!pgmap->owner) {
+			WARN(1, "Missing owner\n");
+			return ERR_PTR(-EINVAL);
+		}
+		break;
 	case MEMORY_DEVICE_FS_DAX:
 		if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
 			WARN(1, "File system DAX not supported\n");
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 5052093d0262..a4847ad65da3 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -518,7 +518,7 @@ EXPORT_SYMBOL(migrate_vma_setup);
  *     handle_pte_fault()
  *       do_anonymous_page()
  * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE
- * private page.
+ * private or coherent page.
  */
 static void migrate_vma_insert_page(struct migrate_vma *migrate,
 				    unsigned long addr,
@@ -594,11 +594,8 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 						page_to_pfn(page));
 		entry = swp_entry_to_pte(swp_entry);
 	} else {
-		/*
-		 * For now we only support migrating to un-addressable device
-		 * memory.
-		 */
-		if (is_zone_device_page(page)) {
+		if (is_zone_device_page(page) &&
+		    !is_device_coherent_page(page)) {
 			pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
 			goto abort;
 		}
@@ -701,10 +698,11 @@ void migrate_vma_pages(struct migrate_vma *migrate)
 
 		mapping = page_mapping(page);
 
-		if (is_device_private_page(newpage)) {
+		if (is_device_private_page(newpage) ||
+		    is_device_coherent_page(newpage)) {
 			/*
-			 * For now only support private anonymous when migrating
-			 * to un-addressable device memory.
+			 * For now only support anonymous memory migrating to
+			 * device private or coherent memory.
 			 */
 			if (mapping) {
 				migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
diff --git a/mm/rmap.c b/mm/rmap.c
index 5bcb334cd6f2..04fac1af870b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1957,7 +1957,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 		/* Update high watermark before we lower rss */
 		update_hiwater_rss(mm);
 
-		if (folio_is_zone_device(folio)) {
+		if (folio_is_device_private(folio)) {
 			unsigned long pfn = folio_pfn(folio);
 			swp_entry_t entry;
 			pte_t swp_pte;
@@ -2131,7 +2131,8 @@ void try_to_migrate(struct folio *folio, enum ttu_flags flags)
 					TTU_SYNC)))
 		return;
 
-	if (folio_is_zone_device(folio) && !folio_is_device_private(folio))
+	if (folio_is_zone_device(folio) &&
+	    (!folio_is_device_private(folio) && !folio_is_device_coherent(folio)))
 		return;
 
 	/*
-- 
2.32.0

[PATCH v4 02/13] mm: handling Non-LRU pages returned by vm_normal_pages

[Alex Sierra]

With DEVICE_COHERENT, we'll soon have vm_normal_pages() return
device-managed anonymous pages that are not LRU pages. Although they
behave like normal pages for purposes of mapping in CPU page, and for
COW. They do not support LRU lists, NUMA migration or THP.

We also introduced a FOLL_LRU flag that adds the same behaviour to
follow_page and related APIs, to allow callers to specify that they
expect to put pages on an LRU list.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
---
 fs/proc/task_mmu.c | 2 +-
 include/linux/mm.h | 3 ++-
 mm/gup.c           | 6 +++++-
 mm/huge_memory.c   | 2 +-
 mm/khugepaged.c    | 9 ++++++---
 mm/ksm.c           | 6 +++---
 mm/madvise.c       | 4 ++--
 mm/memory.c        | 9 ++++++++-
 mm/mempolicy.c     | 2 +-
 mm/migrate.c       | 4 ++--
 mm/mlock.c         | 2 +-
 mm/mprotect.c      | 2 +-
 12 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2d04e3470d4c..2dd8c8a66924 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1792,7 +1792,7 @@ static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
 		return NULL;
 
 	page = vm_normal_page(vma, addr, pte);
-	if (!page)
+	if (!page || is_zone_device_page(page))
 		return NULL;
 
 	if (PageReserved(page))
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc8f326be0ce..d3f43908ff8d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -601,7 +601,7 @@ struct vm_operations_struct {
 #endif
 	/*
 	 * Called by vm_normal_page() for special PTEs to find the
-	 * page for @addr.  This is useful if the default behavior
+	 * page for @addr. This is useful if the default behavior
 	 * (using pte_page()) would not find the correct page.
 	 */
 	struct page *(*find_special_page)(struct vm_area_struct *vma,
@@ -2934,6 +2934,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 #define FOLL_NUMA	0x200	/* force NUMA hinting page fault */
 #define FOLL_MIGRATION	0x400	/* wait for page to replace migration entry */
 #define FOLL_TRIED	0x800	/* a retry, previous pass started an IO */
+#define FOLL_LRU        0x1000  /* return only LRU (anon or page cache) */
 #define FOLL_REMOTE	0x2000	/* we are working on non-current tsk/mm */
 #define FOLL_COW	0x4000	/* internal GUP flag */
 #define FOLL_ANON	0x8000	/* don't do file mappings */
diff --git a/mm/gup.c b/mm/gup.c
index 551264407624..48b45bcc8501 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -532,7 +532,11 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 	}
 
 	page = vm_normal_page(vma, address, pte);
-	if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
+	if ((flags & FOLL_LRU) && ((page && is_zone_device_page(page)) ||
+	    (!page && pte_devmap(pte)))) {
+		page = ERR_PTR(-EEXIST);
+		goto out;
+	} else if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
 		/*
 		 * Only return device mapping pages in the FOLL_GET or FOLL_PIN
 		 * case since they are only valid while holding the pgmap
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a77c78a2b6b5..48182c8fe151 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2906,7 +2906,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 		}
 
 		/* FOLL_DUMP to ignore special (like zero) pages */
-		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU);
 
 		if (IS_ERR(page))
 			continue;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 16be62d493cd..671ac7800e53 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -618,7 +618,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
 			goto out;
 		}
 		page = vm_normal_page(vma, address, pteval);
-		if (unlikely(!page)) {
+		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
 			result = SCAN_PAGE_NULL;
 			goto out;
 		}
@@ -1267,7 +1267,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
 			writable = true;
 
 		page = vm_normal_page(vma, _address, pteval);
-		if (unlikely(!page)) {
+		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
 			result = SCAN_PAGE_NULL;
 			goto out_unmap;
 		}
@@ -1479,7 +1479,8 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 			goto abort;
 
 		page = vm_normal_page(vma, addr, *pte);
-
+		if (WARN_ON_ONCE(page && is_zone_device_page(page)))
+			page = NULL;
 		/*
 		 * Note that uprobe, debugger, or MAP_PRIVATE may change the
 		 * page table, but the new page will not be a subpage of hpage.
@@ -1497,6 +1498,8 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 		if (pte_none(*pte))
 			continue;
 		page = vm_normal_page(vma, addr, *pte);
+		if (WARN_ON_ONCE(page && is_zone_device_page(page)))
+			goto abort;
 		page_remove_rmap(page, vma, false);
 	}
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 54f78c9eecae..400790128102 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -474,7 +474,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
 	do {
 		cond_resched();
 		page = follow_page(vma, addr,
-				FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE);
+				FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE | FOLL_LRU);
 		if (IS_ERR_OR_NULL(page))
 			break;
 		if (PageKsm(page))
@@ -559,7 +559,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
 	if (!vma)
 		goto out;
 
-	page = follow_page(vma, addr, FOLL_GET);
+	page = follow_page(vma, addr, FOLL_GET | FOLL_LRU);
 	if (IS_ERR_OR_NULL(page))
 		goto out;
 	if (PageAnon(page)) {
@@ -2307,7 +2307,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 		while (ksm_scan.address < vma->vm_end) {
 			if (ksm_test_exit(mm))
 				break;
-			*page = follow_page(vma, ksm_scan.address, FOLL_GET);
+			*page = follow_page(vma, ksm_scan.address, FOLL_GET | FOLL_LRU);
 			if (IS_ERR_OR_NULL(*page)) {
 				ksm_scan.address += PAGE_SIZE;
 				cond_resched();
diff --git a/mm/madvise.c b/mm/madvise.c
index d7b4f2602949..e5637181de1b 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -421,7 +421,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			continue;
 
 		page = vm_normal_page(vma, addr, ptent);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 
 		/*
@@ -639,7 +639,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 		}
 
 		page = vm_normal_page(vma, addr, ptent);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 
 		/*
diff --git a/mm/memory.c b/mm/memory.c
index 21dadf03f089..30ecbc715e60 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -624,6 +624,13 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 		if (is_zero_pfn(pfn))
 			return NULL;
 		if (pte_devmap(pte))
+/*
+ * NOTE: New uers of ZONE_DEVICE will not set pte_devmap() and will have
+ * refcounts incremented on their struct pages when they are inserted into
+ * PTEs, thus they are safe to return here. Legacy ZONE_DEVICE pages that set
+ * pte_devmap() do not have refcounts. Example of legacy ZONE_DEVICE is
+ * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
+ */
 			return NULL;
 
 		print_bad_pte(vma, addr, pte, NULL);
@@ -4685,7 +4692,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 	pte = pte_modify(old_pte, vma->vm_page_prot);
 
 	page = vm_normal_page(vma, vmf->address, pte);
-	if (!page)
+	if (!page || is_zone_device_page(page))
 		goto out_map;
 
 	/* TODO: handle PTE-mapped THP */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d39b01fd52fe..abc26890fc95 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -523,7 +523,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
 		if (!pte_present(*pte))
 			continue;
 		page = vm_normal_page(vma, addr, *pte);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 		/*
 		 * vm_normal_page() filters out zero pages, but there might
diff --git a/mm/migrate.c b/mm/migrate.c
index e51588e95f57..f7d1b8312631 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1612,7 +1612,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 		goto out;
 
 	/* FOLL_DUMP to ignore special (like zero) pages */
-	page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+	page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU);
 
 	err = PTR_ERR(page);
 	if (IS_ERR(page))
@@ -1803,7 +1803,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 			goto set_status;
 
 		/* FOLL_DUMP to ignore special (like zero) pages */
-		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU);
 
 		err = PTR_ERR(page);
 		if (IS_ERR(page))
diff --git a/mm/mlock.c b/mm/mlock.c
index 716caf851043..b14e929084cc 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -333,7 +333,7 @@ static int mlock_pte_range(pmd_t *pmd, unsigned long addr,
 		if (!pte_present(*pte))
 			continue;
 		page = vm_normal_page(vma, addr, *pte);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 		if (PageTransCompound(page))
 			continue;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ba5592655ee3..e034aae2a98b 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -95,7 +95,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb,
 					continue;
 
 				page = vm_normal_page(vma, addr, oldpte);
-				if (!page || PageKsm(page))
+				if (!page || is_zone_device_page(page) || PageKsm(page))
 					continue;
 
 				/* Also skip shared copy-on-write pages */
-- 
2.32.0

[PATCH v4 02/13] mm: handling Non-LRU pages returned by vm_normal_pages

[Alex Sierra]

With DEVICE_COHERENT, we'll soon have vm_normal_pages() return
device-managed anonymous pages that are not LRU pages. Although they
behave like normal pages for purposes of mapping in CPU page, and for
COW. They do not support LRU lists, NUMA migration or THP.

We also introduced a FOLL_LRU flag that adds the same behaviour to
follow_page and related APIs, to allow callers to specify that they
expect to put pages on an LRU list.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
---
 fs/proc/task_mmu.c | 2 +-
 include/linux/mm.h | 3 ++-
 mm/gup.c           | 6 +++++-
 mm/huge_memory.c   | 2 +-
 mm/khugepaged.c    | 9 ++++++---
 mm/ksm.c           | 6 +++---
 mm/madvise.c       | 4 ++--
 mm/memory.c        | 9 ++++++++-
 mm/mempolicy.c     | 2 +-
 mm/migrate.c       | 4 ++--
 mm/mlock.c         | 2 +-
 mm/mprotect.c      | 2 +-
 12 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2d04e3470d4c..2dd8c8a66924 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1792,7 +1792,7 @@ static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
 		return NULL;
 
 	page = vm_normal_page(vma, addr, pte);
-	if (!page)
+	if (!page || is_zone_device_page(page))
 		return NULL;
 
 	if (PageReserved(page))
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc8f326be0ce..d3f43908ff8d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -601,7 +601,7 @@ struct vm_operations_struct {
 #endif
 	/*
 	 * Called by vm_normal_page() for special PTEs to find the
-	 * page for @addr.  This is useful if the default behavior
+	 * page for @addr. This is useful if the default behavior
 	 * (using pte_page()) would not find the correct page.
 	 */
 	struct page *(*find_special_page)(struct vm_area_struct *vma,
@@ -2934,6 +2934,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 #define FOLL_NUMA	0x200	/* force NUMA hinting page fault */
 #define FOLL_MIGRATION	0x400	/* wait for page to replace migration entry */
 #define FOLL_TRIED	0x800	/* a retry, previous pass started an IO */
+#define FOLL_LRU        0x1000  /* return only LRU (anon or page cache) */
 #define FOLL_REMOTE	0x2000	/* we are working on non-current tsk/mm */
 #define FOLL_COW	0x4000	/* internal GUP flag */
 #define FOLL_ANON	0x8000	/* don't do file mappings */
diff --git a/mm/gup.c b/mm/gup.c
index 551264407624..48b45bcc8501 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -532,7 +532,11 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 	}
 
 	page = vm_normal_page(vma, address, pte);
-	if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
+	if ((flags & FOLL_LRU) && ((page && is_zone_device_page(page)) ||
+	    (!page && pte_devmap(pte)))) {
+		page = ERR_PTR(-EEXIST);
+		goto out;
+	} else if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
 		/*
 		 * Only return device mapping pages in the FOLL_GET or FOLL_PIN
 		 * case since they are only valid while holding the pgmap
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a77c78a2b6b5..48182c8fe151 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2906,7 +2906,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 		}
 
 		/* FOLL_DUMP to ignore special (like zero) pages */
-		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU);
 
 		if (IS_ERR(page))
 			continue;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 16be62d493cd..671ac7800e53 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -618,7 +618,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
 			goto out;
 		}
 		page = vm_normal_page(vma, address, pteval);
-		if (unlikely(!page)) {
+		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
 			result = SCAN_PAGE_NULL;
 			goto out;
 		}
@@ -1267,7 +1267,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
 			writable = true;
 
 		page = vm_normal_page(vma, _address, pteval);
-		if (unlikely(!page)) {
+		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
 			result = SCAN_PAGE_NULL;
 			goto out_unmap;
 		}
@@ -1479,7 +1479,8 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 			goto abort;
 
 		page = vm_normal_page(vma, addr, *pte);
-
+		if (WARN_ON_ONCE(page && is_zone_device_page(page)))
+			page = NULL;
 		/*
 		 * Note that uprobe, debugger, or MAP_PRIVATE may change the
 		 * page table, but the new page will not be a subpage of hpage.
@@ -1497,6 +1498,8 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
 		if (pte_none(*pte))
 			continue;
 		page = vm_normal_page(vma, addr, *pte);
+		if (WARN_ON_ONCE(page && is_zone_device_page(page)))
+			goto abort;
 		page_remove_rmap(page, vma, false);
 	}
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 54f78c9eecae..400790128102 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -474,7 +474,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
 	do {
 		cond_resched();
 		page = follow_page(vma, addr,
-				FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE);
+				FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE | FOLL_LRU);
 		if (IS_ERR_OR_NULL(page))
 			break;
 		if (PageKsm(page))
@@ -559,7 +559,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
 	if (!vma)
 		goto out;
 
-	page = follow_page(vma, addr, FOLL_GET);
+	page = follow_page(vma, addr, FOLL_GET | FOLL_LRU);
 	if (IS_ERR_OR_NULL(page))
 		goto out;
 	if (PageAnon(page)) {
@@ -2307,7 +2307,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 		while (ksm_scan.address < vma->vm_end) {
 			if (ksm_test_exit(mm))
 				break;
-			*page = follow_page(vma, ksm_scan.address, FOLL_GET);
+			*page = follow_page(vma, ksm_scan.address, FOLL_GET | FOLL_LRU);
 			if (IS_ERR_OR_NULL(*page)) {
 				ksm_scan.address += PAGE_SIZE;
 				cond_resched();
diff --git a/mm/madvise.c b/mm/madvise.c
index d7b4f2602949..e5637181de1b 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -421,7 +421,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			continue;
 
 		page = vm_normal_page(vma, addr, ptent);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 
 		/*
@@ -639,7 +639,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 		}
 
 		page = vm_normal_page(vma, addr, ptent);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 
 		/*
diff --git a/mm/memory.c b/mm/memory.c
index 21dadf03f089..30ecbc715e60 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -624,6 +624,13 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 		if (is_zero_pfn(pfn))
 			return NULL;
 		if (pte_devmap(pte))
+/*
+ * NOTE: New uers of ZONE_DEVICE will not set pte_devmap() and will have
+ * refcounts incremented on their struct pages when they are inserted into
+ * PTEs, thus they are safe to return here. Legacy ZONE_DEVICE pages that set
+ * pte_devmap() do not have refcounts. Example of legacy ZONE_DEVICE is
+ * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
+ */
 			return NULL;
 
 		print_bad_pte(vma, addr, pte, NULL);
@@ -4685,7 +4692,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
 	pte = pte_modify(old_pte, vma->vm_page_prot);
 
 	page = vm_normal_page(vma, vmf->address, pte);
-	if (!page)
+	if (!page || is_zone_device_page(page))
 		goto out_map;
 
 	/* TODO: handle PTE-mapped THP */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d39b01fd52fe..abc26890fc95 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -523,7 +523,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
 		if (!pte_present(*pte))
 			continue;
 		page = vm_normal_page(vma, addr, *pte);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 		/*
 		 * vm_normal_page() filters out zero pages, but there might
diff --git a/mm/migrate.c b/mm/migrate.c
index e51588e95f57..f7d1b8312631 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1612,7 +1612,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 		goto out;
 
 	/* FOLL_DUMP to ignore special (like zero) pages */
-	page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+	page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU);
 
 	err = PTR_ERR(page);
 	if (IS_ERR(page))
@@ -1803,7 +1803,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 			goto set_status;
 
 		/* FOLL_DUMP to ignore special (like zero) pages */
-		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP | FOLL_LRU);
 
 		err = PTR_ERR(page);
 		if (IS_ERR(page))
diff --git a/mm/mlock.c b/mm/mlock.c
index 716caf851043..b14e929084cc 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -333,7 +333,7 @@ static int mlock_pte_range(pmd_t *pmd, unsigned long addr,
 		if (!pte_present(*pte))
 			continue;
 		page = vm_normal_page(vma, addr, *pte);
-		if (!page)
+		if (!page || is_zone_device_page(page))
 			continue;
 		if (PageTransCompound(page))
 			continue;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ba5592655ee3..e034aae2a98b 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -95,7 +95,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb,
 					continue;
 
 				page = vm_normal_page(vma, addr, oldpte);
-				if (!page || PageKsm(page))
+				if (!page || is_zone_device_page(page) || PageKsm(page))
 					continue;
 
 				/* Also skip shared copy-on-write pages */
-- 
2.32.0

[PATCH v4 03/13] mm: add device coherent vma selection for memory migration

[Alex Sierra]

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>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/migrate.h |  1 +
 mm/migrate_device.c     | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 069a89e847f3..b84908debe5c 100644
--- 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 a4847ad65da3..18bc6483f63a 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -148,15 +148,21 @@ 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)) {
+			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;
 		}
-- 
2.32.0

[PATCH v4 03/13] mm: add device coherent vma selection for memory migration

[Alex Sierra]

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>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/migrate.h |  1 +
 mm/migrate_device.c     | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 069a89e847f3..b84908debe5c 100644
--- 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 a4847ad65da3..18bc6483f63a 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -148,15 +148,21 @@ 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)) {
+			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;
 		}
-- 
2.32.0

[PATCH v4 04/13] mm: remove the vma check in migrate_vma_setup()

[Alex Sierra]

From: Alistair Popple <apopple@nvidia.com>

migrate_vma_setup() checks that a valid vma is passed so that the page
tables can be walked to find the pfns associated with a given address
range. However in some cases the pfns are already known, such as when
migrating device coherent pages during pin_user_pages() meaning a valid
vma isn't required.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/migrate_device.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 18bc6483f63a..cf9668376c5a 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -486,24 +486,24 @@ int migrate_vma_setup(struct migrate_vma *args)
 
 	args->start &= PAGE_MASK;
 	args->end &= PAGE_MASK;
-	if (!args->vma || is_vm_hugetlb_page(args->vma) ||
-	    (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))
-		return -EINVAL;
-	if (nr_pages <= 0)
-		return -EINVAL;
-	if (args->start < args->vma->vm_start ||
-	    args->start >= args->vma->vm_end)
-		return -EINVAL;
-	if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end)
-		return -EINVAL;
 	if (!args->src || !args->dst)
 		return -EINVAL;
-
-	memset(args->src, 0, sizeof(*args->src) * nr_pages);
-	args->cpages = 0;
-	args->npages = 0;
-
-	migrate_vma_collect(args);
+	if (args->vma) {
+		if (is_vm_hugetlb_page(args->vma) ||
+		    (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))
+			return -EINVAL;
+		if (args->start < args->vma->vm_start ||
+		    args->start >= args->vma->vm_end)
+			return -EINVAL;
+		if (args->end <= args->vma->vm_start ||
+		    args->end > args->vma->vm_end)
+			return -EINVAL;
+		memset(args->src, 0, sizeof(*args->src) * nr_pages);
+		args->cpages = 0;
+		args->npages = 0;
+
+		migrate_vma_collect(args);
+	}
 
 	if (args->cpages)
 		migrate_vma_unmap(args);
@@ -685,7 +685,7 @@ void migrate_vma_pages(struct migrate_vma *migrate)
 			continue;
 		}
 
-		if (!page) {
+		if (!page && migrate->vma) {
 			if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE))
 				continue;
 			if (!notified) {
-- 
2.32.0

[PATCH v4 04/13] mm: remove the vma check in migrate_vma_setup()

[Alex Sierra]

From: Alistair Popple <apopple@nvidia.com>

migrate_vma_setup() checks that a valid vma is passed so that the page
tables can be walked to find the pfns associated with a given address
range. However in some cases the pfns are already known, such as when
migrating device coherent pages during pin_user_pages() meaning a valid
vma isn't required.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/migrate_device.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 18bc6483f63a..cf9668376c5a 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -486,24 +486,24 @@ int migrate_vma_setup(struct migrate_vma *args)
 
 	args->start &= PAGE_MASK;
 	args->end &= PAGE_MASK;
-	if (!args->vma || is_vm_hugetlb_page(args->vma) ||
-	    (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))
-		return -EINVAL;
-	if (nr_pages <= 0)
-		return -EINVAL;
-	if (args->start < args->vma->vm_start ||
-	    args->start >= args->vma->vm_end)
-		return -EINVAL;
-	if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end)
-		return -EINVAL;
 	if (!args->src || !args->dst)
 		return -EINVAL;
-
-	memset(args->src, 0, sizeof(*args->src) * nr_pages);
-	args->cpages = 0;
-	args->npages = 0;
-
-	migrate_vma_collect(args);
+	if (args->vma) {
+		if (is_vm_hugetlb_page(args->vma) ||
+		    (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))
+			return -EINVAL;
+		if (args->start < args->vma->vm_start ||
+		    args->start >= args->vma->vm_end)
+			return -EINVAL;
+		if (args->end <= args->vma->vm_start ||
+		    args->end > args->vma->vm_end)
+			return -EINVAL;
+		memset(args->src, 0, sizeof(*args->src) * nr_pages);
+		args->cpages = 0;
+		args->npages = 0;
+
+		migrate_vma_collect(args);
+	}
 
 	if (args->cpages)
 		migrate_vma_unmap(args);
@@ -685,7 +685,7 @@ void migrate_vma_pages(struct migrate_vma *migrate)
 			continue;
 		}
 
-		if (!page) {
+		if (!page && migrate->vma) {
 			if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE))
 				continue;
 			if (!notified) {
-- 
2.32.0

[PATCH v4 05/13] mm/gup: migrate device coherent pages when pinning instead of failing

[Alex Sierra]

From: Alistair Popple <apopple@nvidia.com>

Currently any attempts to pin a device coherent page will fail. This is
because device coherent pages need to be managed by a device driver, and
pinning them would prevent a driver from migrating them off the device.

However this is no reason to fail pinning of these pages. These are
coherent and accessible from the CPU so can be migrated just like
pinning ZONE_MOVABLE pages. So instead of failing all attempts to pin
them first try migrating them out of ZONE_DEVICE.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
[hch: rebased to the split device memory checks,
      moved migrate_device_page to migrate_device.c]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c            | 47 +++++++++++++++++++++++++++++++++++-----
 mm/internal.h       |  1 +
 mm/migrate_device.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+), 5 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 48b45bcc8501..e6093c31f932 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1895,9 +1895,43 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
 			continue;
 		prev_folio = folio;
 
-		if (folio_is_pinnable(folio))
+		/*
+		 * Device private pages will get faulted in during gup so it
+		 * shouldn't be possible to see one here.
+		 */
+		if (WARN_ON_ONCE(folio_is_device_private(folio))) {
+			ret = -EFAULT;
+			goto unpin_pages;
+		}
+
+		/*
+		 * Device coherent pages are managed by a driver and should not
+		 * be pinned indefinitely as it prevents the driver moving the
+		 * page. So when trying to pin with FOLL_LONGTERM instead try
+		 * to migrate the page out of device memory.
+		 */
+		if (folio_is_device_coherent(folio)) {
+			WARN_ON_ONCE(PageCompound(&folio->page));
+
+			/*
+			 * Migration will fail if the page is pinned, so convert
+			 * the pin on the source page to a normal reference.
+			 */
+			if (gup_flags & FOLL_PIN) {
+				get_page(&folio->page);
+				unpin_user_page(&folio->page);
+			}
+
+			pages[i] = migrate_device_page(&folio->page, gup_flags);
+			if (!pages[i]) {
+				ret = -EBUSY;
+				goto unpin_pages;
+			}
 			continue;
+		}
 
+		if (folio_is_pinnable(folio))
+			continue;
 		/*
 		 * Try to move out any movable page before pinning the range.
 		 */
@@ -1933,10 +1967,13 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
 	return nr_pages;
 
 unpin_pages:
-	if (gup_flags & FOLL_PIN) {
-		unpin_user_pages(pages, nr_pages);
-	} else {
-		for (i = 0; i < nr_pages; i++)
+	for (i = 0; i < nr_pages; i++) {
+		if (!pages[i])
+			continue;
+
+		if (gup_flags & FOLL_PIN)
+			unpin_user_page(pages[i]);
+		else
 			put_page(pages[i]);
 	}
 
diff --git a/mm/internal.h b/mm/internal.h
index c0f8fbe0445b..eeab4ee7a4a3 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -853,6 +853,7 @@ int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
 		      unsigned long addr, int page_nid, int *flags);
 
 void free_zone_device_page(struct page *page);
+struct page *migrate_device_page(struct page *page, unsigned int gup_flags);
 
 /*
  * mm/gup.c
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index cf9668376c5a..5decd26dd551 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -794,3 +794,56 @@ void migrate_vma_finalize(struct migrate_vma *migrate)
 	}
 }
 EXPORT_SYMBOL(migrate_vma_finalize);
+
+/*
+ * Migrate a device coherent page back to normal memory.  The caller should have
+ * a reference on page which will be copied to the new page if migration is
+ * successful or dropped on failure.
+ */
+struct page *migrate_device_page(struct page *page, unsigned int gup_flags)
+{
+	unsigned long src_pfn, dst_pfn = 0;
+	struct migrate_vma args;
+	struct page *dpage;
+
+	lock_page(page);
+	src_pfn = migrate_pfn(page_to_pfn(page)) | MIGRATE_PFN_MIGRATE;
+	args.src = &src_pfn;
+	args.dst = &dst_pfn;
+	args.cpages = 1;
+	args.npages = 1;
+	args.vma = NULL;
+	migrate_vma_setup(&args);
+	if (!(src_pfn & MIGRATE_PFN_MIGRATE))
+		return NULL;
+
+	dpage = alloc_pages(GFP_USER | __GFP_NOWARN, 0);
+
+	/*
+	 * get/pin the new page now so we don't have to retry gup after
+	 * migrating. We already have a reference so this should never fail.
+	 */
+	if (dpage && WARN_ON_ONCE(!try_grab_page(dpage, gup_flags))) {
+		__free_pages(dpage, 0);
+		dpage = NULL;
+	}
+
+	if (dpage) {
+		lock_page(dpage);
+		dst_pfn = migrate_pfn(page_to_pfn(dpage));
+	}
+
+	migrate_vma_pages(&args);
+	if (src_pfn & MIGRATE_PFN_MIGRATE)
+		copy_highpage(dpage, page);
+	migrate_vma_finalize(&args);
+	if (dpage && !(src_pfn & MIGRATE_PFN_MIGRATE)) {
+		if (gup_flags & FOLL_PIN)
+			unpin_user_page(dpage);
+		else
+			put_page(dpage);
+		dpage = NULL;
+	}
+
+	return dpage;
+}
-- 
2.32.0

[PATCH v4 05/13] mm/gup: migrate device coherent pages when pinning instead of failing

[Alex Sierra]

From: Alistair Popple <apopple@nvidia.com>

Currently any attempts to pin a device coherent page will fail. This is
because device coherent pages need to be managed by a device driver, and
pinning them would prevent a driver from migrating them off the device.

However this is no reason to fail pinning of these pages. These are
coherent and accessible from the CPU so can be migrated just like
pinning ZONE_MOVABLE pages. So instead of failing all attempts to pin
them first try migrating them out of ZONE_DEVICE.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
[hch: rebased to the split device memory checks,
      moved migrate_device_page to migrate_device.c]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/gup.c            | 47 +++++++++++++++++++++++++++++++++++-----
 mm/internal.h       |  1 +
 mm/migrate_device.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+), 5 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 48b45bcc8501..e6093c31f932 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1895,9 +1895,43 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
 			continue;
 		prev_folio = folio;
 
-		if (folio_is_pinnable(folio))
+		/*
+		 * Device private pages will get faulted in during gup so it
+		 * shouldn't be possible to see one here.
+		 */
+		if (WARN_ON_ONCE(folio_is_device_private(folio))) {
+			ret = -EFAULT;
+			goto unpin_pages;
+		}
+
+		/*
+		 * Device coherent pages are managed by a driver and should not
+		 * be pinned indefinitely as it prevents the driver moving the
+		 * page. So when trying to pin with FOLL_LONGTERM instead try
+		 * to migrate the page out of device memory.
+		 */
+		if (folio_is_device_coherent(folio)) {
+			WARN_ON_ONCE(PageCompound(&folio->page));
+
+			/*
+			 * Migration will fail if the page is pinned, so convert
+			 * the pin on the source page to a normal reference.
+			 */
+			if (gup_flags & FOLL_PIN) {
+				get_page(&folio->page);
+				unpin_user_page(&folio->page);
+			}
+
+			pages[i] = migrate_device_page(&folio->page, gup_flags);
+			if (!pages[i]) {
+				ret = -EBUSY;
+				goto unpin_pages;
+			}
 			continue;
+		}
 
+		if (folio_is_pinnable(folio))
+			continue;
 		/*
 		 * Try to move out any movable page before pinning the range.
 		 */
@@ -1933,10 +1967,13 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
 	return nr_pages;
 
 unpin_pages:
-	if (gup_flags & FOLL_PIN) {
-		unpin_user_pages(pages, nr_pages);
-	} else {
-		for (i = 0; i < nr_pages; i++)
+	for (i = 0; i < nr_pages; i++) {
+		if (!pages[i])
+			continue;
+
+		if (gup_flags & FOLL_PIN)
+			unpin_user_page(pages[i]);
+		else
 			put_page(pages[i]);
 	}
 
diff --git a/mm/internal.h b/mm/internal.h
index c0f8fbe0445b..eeab4ee7a4a3 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -853,6 +853,7 @@ int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
 		      unsigned long addr, int page_nid, int *flags);
 
 void free_zone_device_page(struct page *page);
+struct page *migrate_device_page(struct page *page, unsigned int gup_flags);
 
 /*
  * mm/gup.c
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index cf9668376c5a..5decd26dd551 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -794,3 +794,56 @@ void migrate_vma_finalize(struct migrate_vma *migrate)
 	}
 }
 EXPORT_SYMBOL(migrate_vma_finalize);
+
+/*
+ * Migrate a device coherent page back to normal memory.  The caller should have
+ * a reference on page which will be copied to the new page if migration is
+ * successful or dropped on failure.
+ */
+struct page *migrate_device_page(struct page *page, unsigned int gup_flags)
+{
+	unsigned long src_pfn, dst_pfn = 0;
+	struct migrate_vma args;
+	struct page *dpage;
+
+	lock_page(page);
+	src_pfn = migrate_pfn(page_to_pfn(page)) | MIGRATE_PFN_MIGRATE;
+	args.src = &src_pfn;
+	args.dst = &dst_pfn;
+	args.cpages = 1;
+	args.npages = 1;
+	args.vma = NULL;
+	migrate_vma_setup(&args);
+	if (!(src_pfn & MIGRATE_PFN_MIGRATE))
+		return NULL;
+
+	dpage = alloc_pages(GFP_USER | __GFP_NOWARN, 0);
+
+	/*
+	 * get/pin the new page now so we don't have to retry gup after
+	 * migrating. We already have a reference so this should never fail.
+	 */
+	if (dpage && WARN_ON_ONCE(!try_grab_page(dpage, gup_flags))) {
+		__free_pages(dpage, 0);
+		dpage = NULL;
+	}
+
+	if (dpage) {
+		lock_page(dpage);
+		dst_pfn = migrate_pfn(page_to_pfn(dpage));
+	}
+
+	migrate_vma_pages(&args);
+	if (src_pfn & MIGRATE_PFN_MIGRATE)
+		copy_highpage(dpage, page);
+	migrate_vma_finalize(&args);
+	if (dpage && !(src_pfn & MIGRATE_PFN_MIGRATE)) {
+		if (gup_flags & FOLL_PIN)
+			unpin_user_page(dpage);
+		else
+			put_page(dpage);
+		dpage = NULL;
+	}
+
+	return dpage;
+}
-- 
2.32.0

[PATCH v4 06/13] drm/amdkfd: add SPM support for SVM

[Alex Sierra]

When CPU is connected throug XGMI, it has coherent
access to VRAM resource. In this case that resource
is taken from a table in the device gmc aperture base.
This resource is used along with the device type, which could
be DEVICE_PRIVATE or DEVICE_COHERENT to create the device
page map region.
Also, MIGRATE_VMA_SELECT_DEVICE_COHERENT flag is selected for
coherent type case during migration to device.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 34 +++++++++++++++---------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 997650d597ec..39b8c4710caf 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -671,13 +671,15 @@ svm_migrate_vma_to_ram(struct amdgpu_device *adev, struct svm_range *prange,
 	migrate.vma = vma;
 	migrate.start = start;
 	migrate.end = end;
-	migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
 	migrate.pgmap_owner = SVM_ADEV_PGMAP_OWNER(adev);
+	if (adev->gmc.xgmi.connected_to_cpu)
+		migrate.flags = MIGRATE_VMA_SELECT_DEVICE_COHERENT;
+	else
+		migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
 
 	buf = kvcalloc(npages,
 		       2 * sizeof(*migrate.src) + sizeof(uint64_t) + sizeof(dma_addr_t),
 		       GFP_KERNEL);
-
 	if (!buf)
 		goto out;
 
@@ -947,7 +949,7 @@ int svm_migrate_init(struct amdgpu_device *adev)
 {
 	struct kfd_dev *kfddev = adev->kfd.dev;
 	struct dev_pagemap *pgmap;
-	struct resource *res;
+	struct resource *res = NULL;
 	unsigned long size;
 	void *r;
 
@@ -962,28 +964,34 @@ int svm_migrate_init(struct amdgpu_device *adev)
 	 * should remove reserved size
 	 */
 	size = ALIGN(adev->gmc.real_vram_size, 2ULL << 20);
-	res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
-	if (IS_ERR(res))
-		return -ENOMEM;
+	if (adev->gmc.xgmi.connected_to_cpu) {
+		pgmap->range.start = adev->gmc.aper_base;
+		pgmap->range.end = adev->gmc.aper_base + adev->gmc.aper_size - 1;
+		pgmap->type = MEMORY_DEVICE_COHERENT;
+	} else {
+		res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
+		if (IS_ERR(res))
+			return -ENOMEM;
+		pgmap->range.start = res->start;
+		pgmap->range.end = res->end;
+		pgmap->type = MEMORY_DEVICE_PRIVATE;
+	}
 
-	pgmap->type = MEMORY_DEVICE_PRIVATE;
 	pgmap->nr_range = 1;
-	pgmap->range.start = res->start;
-	pgmap->range.end = res->end;
 	pgmap->ops = &svm_migrate_pgmap_ops;
 	pgmap->owner = SVM_ADEV_PGMAP_OWNER(adev);
-	pgmap->flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
-
+	pgmap->flags = 0;
 	/* Device manager releases device-specific resources, memory region and
 	 * pgmap when driver disconnects from device.
 	 */
 	r = devm_memremap_pages(adev->dev, pgmap);
 	if (IS_ERR(r)) {
 		pr_err("failed to register HMM device memory\n");
-
 		/* Disable SVM support capability */
 		pgmap->type = 0;
-		devm_release_mem_region(adev->dev, res->start, resource_size(res));
+		if (pgmap->type == MEMORY_DEVICE_PRIVATE)
+			devm_release_mem_region(adev->dev, res->start,
+						res->end - res->start + 1);
 		return PTR_ERR(r);
 	}
 
-- 
2.32.0

[PATCH v4 06/13] drm/amdkfd: add SPM support for SVM

[Alex Sierra]

When CPU is connected throug XGMI, it has coherent
access to VRAM resource. In this case that resource
is taken from a table in the device gmc aperture base.
This resource is used along with the device type, which could
be DEVICE_PRIVATE or DEVICE_COHERENT to create the device
page map region.
Also, MIGRATE_VMA_SELECT_DEVICE_COHERENT flag is selected for
coherent type case during migration to device.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 34 +++++++++++++++---------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 997650d597ec..39b8c4710caf 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -671,13 +671,15 @@ svm_migrate_vma_to_ram(struct amdgpu_device *adev, struct svm_range *prange,
 	migrate.vma = vma;
 	migrate.start = start;
 	migrate.end = end;
-	migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
 	migrate.pgmap_owner = SVM_ADEV_PGMAP_OWNER(adev);
+	if (adev->gmc.xgmi.connected_to_cpu)
+		migrate.flags = MIGRATE_VMA_SELECT_DEVICE_COHERENT;
+	else
+		migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
 
 	buf = kvcalloc(npages,
 		       2 * sizeof(*migrate.src) + sizeof(uint64_t) + sizeof(dma_addr_t),
 		       GFP_KERNEL);
-
 	if (!buf)
 		goto out;
 
@@ -947,7 +949,7 @@ int svm_migrate_init(struct amdgpu_device *adev)
 {
 	struct kfd_dev *kfddev = adev->kfd.dev;
 	struct dev_pagemap *pgmap;
-	struct resource *res;
+	struct resource *res = NULL;
 	unsigned long size;
 	void *r;
 
@@ -962,28 +964,34 @@ int svm_migrate_init(struct amdgpu_device *adev)
 	 * should remove reserved size
 	 */
 	size = ALIGN(adev->gmc.real_vram_size, 2ULL << 20);
-	res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
-	if (IS_ERR(res))
-		return -ENOMEM;
+	if (adev->gmc.xgmi.connected_to_cpu) {
+		pgmap->range.start = adev->gmc.aper_base;
+		pgmap->range.end = adev->gmc.aper_base + adev->gmc.aper_size - 1;
+		pgmap->type = MEMORY_DEVICE_COHERENT;
+	} else {
+		res = devm_request_free_mem_region(adev->dev, &iomem_resource, size);
+		if (IS_ERR(res))
+			return -ENOMEM;
+		pgmap->range.start = res->start;
+		pgmap->range.end = res->end;
+		pgmap->type = MEMORY_DEVICE_PRIVATE;
+	}
 
-	pgmap->type = MEMORY_DEVICE_PRIVATE;
 	pgmap->nr_range = 1;
-	pgmap->range.start = res->start;
-	pgmap->range.end = res->end;
 	pgmap->ops = &svm_migrate_pgmap_ops;
 	pgmap->owner = SVM_ADEV_PGMAP_OWNER(adev);
-	pgmap->flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
-
+	pgmap->flags = 0;
 	/* Device manager releases device-specific resources, memory region and
 	 * pgmap when driver disconnects from device.
 	 */
 	r = devm_memremap_pages(adev->dev, pgmap);
 	if (IS_ERR(r)) {
 		pr_err("failed to register HMM device memory\n");
-
 		/* Disable SVM support capability */
 		pgmap->type = 0;
-		devm_release_mem_region(adev->dev, res->start, resource_size(res));
+		if (pgmap->type == MEMORY_DEVICE_PRIVATE)
+			devm_release_mem_region(adev->dev, res->start,
+						res->end - res->start + 1);
 		return PTR_ERR(r);
 	}
 
-- 
2.32.0

[PATCH v4 07/13] lib: test_hmm add ioctl to get zone device type

[Alex Sierra]

new ioctl cmd added to query zone device type. This will be
used once the test_hmm adds zone device coherent type.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/test_hmm.c      | 23 +++++++++++++++++++++--
 lib/test_hmm_uapi.h |  8 ++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index cfe632047839..7a27584484ce 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -87,6 +87,7 @@ struct dmirror_chunk {
 struct dmirror_device {
 	struct cdev		cdevice;
 	struct hmm_devmem	*devmem;
+	unsigned int            zone_device_type;
 
 	unsigned int		devmem_capacity;
 	unsigned int		devmem_count;
@@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
 	return ret;
 }
 
+static int dmirror_get_device_type(struct dmirror *dmirror,
+			    struct hmm_dmirror_cmd *cmd)
+{
+	mutex_lock(&dmirror->mutex);
+	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
+	mutex_unlock(&dmirror->mutex);
+
+	return 0;
+}
 static long dmirror_fops_unlocked_ioctl(struct file *filp,
 					unsigned int command,
 					unsigned long arg)
@@ -1076,6 +1086,9 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
 		ret = dmirror_snapshot(dmirror, &cmd);
 		break;
 
+	case HMM_DMIRROR_GET_MEM_DEV_TYPE:
+		ret = dmirror_get_device_type(dmirror, &cmd);
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -1260,14 +1273,20 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
 static int __init hmm_dmirror_init(void)
 {
 	int ret;
-	int id;
+	int id = 0;
+	int ndevices = 0;
 
 	ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
 				  "HMM_DMIRROR");
 	if (ret)
 		goto err_unreg;
 
-	for (id = 0; id < DMIRROR_NDEVICES; id++) {
+	memset(dmirror_devices, 0, DMIRROR_NDEVICES * sizeof(dmirror_devices[0]));
+	dmirror_devices[ndevices++].zone_device_type =
+				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
+	dmirror_devices[ndevices++].zone_device_type =
+				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
+	for (id = 0; id < ndevices; id++) {
 		ret = dmirror_device_init(dmirror_devices + id, id);
 		if (ret)
 			goto err_chrdev;
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index f14dea5dcd06..17f842f1aa02 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -19,6 +19,7 @@
  * @npages: (in) number of pages to read/write
  * @cpages: (out) number of pages copied
  * @faults: (out) number of device page faults seen
+ * @zone_device_type: (out) zone device memory type
  */
 struct hmm_dmirror_cmd {
 	__u64		addr;
@@ -26,6 +27,7 @@ struct hmm_dmirror_cmd {
 	__u64		npages;
 	__u64		cpages;
 	__u64		faults;
+	__u64		zone_device_type;
 };
 
 /* Expose the address space of the calling process through hmm device file */
@@ -35,6 +37,7 @@ struct hmm_dmirror_cmd {
 #define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x03, struct hmm_dmirror_cmd)
 #define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
 #define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x05, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
 
 /*
  * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
@@ -62,4 +65,9 @@ enum {
 	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
 };
 
+enum {
+	/* 0 is reserved to catch uninitialized type fields */
+	HMM_DMIRROR_MEMORY_DEVICE_PRIVATE = 1,
+};
+
 #endif /* _LIB_TEST_HMM_UAPI_H */
-- 
2.32.0

[PATCH v4 07/13] lib: test_hmm add ioctl to get zone device type

[Alex Sierra]

new ioctl cmd added to query zone device type. This will be
used once the test_hmm adds zone device coherent type.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/test_hmm.c      | 23 +++++++++++++++++++++--
 lib/test_hmm_uapi.h |  8 ++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index cfe632047839..7a27584484ce 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -87,6 +87,7 @@ struct dmirror_chunk {
 struct dmirror_device {
 	struct cdev		cdevice;
 	struct hmm_devmem	*devmem;
+	unsigned int            zone_device_type;
 
 	unsigned int		devmem_capacity;
 	unsigned int		devmem_count;
@@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
 	return ret;
 }
 
+static int dmirror_get_device_type(struct dmirror *dmirror,
+			    struct hmm_dmirror_cmd *cmd)
+{
+	mutex_lock(&dmirror->mutex);
+	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
+	mutex_unlock(&dmirror->mutex);
+
+	return 0;
+}
 static long dmirror_fops_unlocked_ioctl(struct file *filp,
 					unsigned int command,
 					unsigned long arg)
@@ -1076,6 +1086,9 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
 		ret = dmirror_snapshot(dmirror, &cmd);
 		break;
 
+	case HMM_DMIRROR_GET_MEM_DEV_TYPE:
+		ret = dmirror_get_device_type(dmirror, &cmd);
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -1260,14 +1273,20 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
 static int __init hmm_dmirror_init(void)
 {
 	int ret;
-	int id;
+	int id = 0;
+	int ndevices = 0;
 
 	ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
 				  "HMM_DMIRROR");
 	if (ret)
 		goto err_unreg;
 
-	for (id = 0; id < DMIRROR_NDEVICES; id++) {
+	memset(dmirror_devices, 0, DMIRROR_NDEVICES * sizeof(dmirror_devices[0]));
+	dmirror_devices[ndevices++].zone_device_type =
+				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
+	dmirror_devices[ndevices++].zone_device_type =
+				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
+	for (id = 0; id < ndevices; id++) {
 		ret = dmirror_device_init(dmirror_devices + id, id);
 		if (ret)
 			goto err_chrdev;
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index f14dea5dcd06..17f842f1aa02 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -19,6 +19,7 @@
  * @npages: (in) number of pages to read/write
  * @cpages: (out) number of pages copied
  * @faults: (out) number of device page faults seen
+ * @zone_device_type: (out) zone device memory type
  */
 struct hmm_dmirror_cmd {
 	__u64		addr;
@@ -26,6 +27,7 @@ struct hmm_dmirror_cmd {
 	__u64		npages;
 	__u64		cpages;
 	__u64		faults;
+	__u64		zone_device_type;
 };
 
 /* Expose the address space of the calling process through hmm device file */
@@ -35,6 +37,7 @@ struct hmm_dmirror_cmd {
 #define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x03, struct hmm_dmirror_cmd)
 #define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
 #define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x05, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
 
 /*
  * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
@@ -62,4 +65,9 @@ enum {
 	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
 };
 
+enum {
+	/* 0 is reserved to catch uninitialized type fields */
+	HMM_DMIRROR_MEMORY_DEVICE_PRIVATE = 1,
+};
+
 #endif /* _LIB_TEST_HMM_UAPI_H */
-- 
2.32.0

[PATCH v4 08/13] lib: test_hmm add module param for zone device type

[Alex Sierra]

In order to configure device coherent in test_hmm, two module parameters
should be passed, which correspond to the SP start address of each
device (2) spm_addr_dev0 & spm_addr_dev1. If no parameters are passed,
private device type is configured.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/test_hmm.c      | 73 ++++++++++++++++++++++++++++++++-------------
 lib/test_hmm_uapi.h |  1 +
 2 files changed, 53 insertions(+), 21 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 7a27584484ce..15747f70c5bc 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -37,6 +37,16 @@
 #define DEVMEM_CHUNK_SIZE		(256 * 1024 * 1024U)
 #define DEVMEM_CHUNKS_RESERVE		16
 
+static unsigned long spm_addr_dev0;
+module_param(spm_addr_dev0, long, 0644);
+MODULE_PARM_DESC(spm_addr_dev0,
+		"Specify start address for SPM (special purpose memory) used for device 0. By setting this Coherent device type will be used. Make sure spm_addr_dev1 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
+
+static unsigned long spm_addr_dev1;
+module_param(spm_addr_dev1, long, 0644);
+MODULE_PARM_DESC(spm_addr_dev1,
+		"Specify start address for SPM (special purpose memory) used for device 1. By setting this Coherent device type will be used. Make sure spm_addr_dev0 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
+
 static const struct dev_pagemap_ops dmirror_devmem_ops;
 static const struct mmu_interval_notifier_ops dmirror_min_ops;
 static dev_t dmirror_dev;
@@ -455,28 +465,44 @@ static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
 	return ret;
 }
 
-static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
+static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
 				   struct page **ppage)
 {
 	struct dmirror_chunk *devmem;
-	struct resource *res;
+	struct resource *res = NULL;
 	unsigned long pfn;
 	unsigned long pfn_first;
 	unsigned long pfn_last;
 	void *ptr;
+	int ret = -ENOMEM;
 
 	devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
 	if (!devmem)
-		return false;
+		return ret;
 
-	res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
-				      "hmm_dmirror");
-	if (IS_ERR(res))
+	switch (mdevice->zone_device_type) {
+	case HMM_DMIRROR_MEMORY_DEVICE_PRIVATE:
+		res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
+					      "hmm_dmirror");
+		if (IS_ERR_OR_NULL(res))
+			goto err_devmem;
+		devmem->pagemap.range.start = res->start;
+		devmem->pagemap.range.end = res->end;
+		devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
+		break;
+	case HMM_DMIRROR_MEMORY_DEVICE_COHERENT:
+		devmem->pagemap.range.start = (MINOR(mdevice->cdevice.dev) - 2) ?
+							spm_addr_dev0 :
+							spm_addr_dev1;
+		devmem->pagemap.range.end = devmem->pagemap.range.start +
+					    DEVMEM_CHUNK_SIZE - 1;
+		devmem->pagemap.type = MEMORY_DEVICE_COHERENT;
+		break;
+	default:
+		ret = -EINVAL;
 		goto err_devmem;
+	}
 
-	devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
-	devmem->pagemap.range.start = res->start;
-	devmem->pagemap.range.end = res->end;
 	devmem->pagemap.nr_range = 1;
 	devmem->pagemap.ops = &dmirror_devmem_ops;
 	devmem->pagemap.owner = mdevice;
@@ -497,10 +523,14 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
 		mdevice->devmem_capacity = new_capacity;
 		mdevice->devmem_chunks = new_chunks;
 	}
-
 	ptr = memremap_pages(&devmem->pagemap, numa_node_id());
-	if (IS_ERR(ptr))
+	if (IS_ERR_OR_NULL(ptr)) {
+		if (ptr)
+			ret = PTR_ERR(ptr);
+		else
+			ret = -EFAULT;
 		goto err_release;
+	}
 
 	devmem->mdevice = mdevice;
 	pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
@@ -529,15 +559,17 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
 	}
 	spin_unlock(&mdevice->lock);
 
-	return true;
+	return 0;
 
 err_release:
 	mutex_unlock(&mdevice->devmem_lock);
-	release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
+	if (res && devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
+		release_mem_region(devmem->pagemap.range.start,
+				   range_len(&devmem->pagemap.range));
 err_devmem:
 	kfree(devmem);
 
-	return false;
+	return ret;
 }
 
 static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
@@ -562,7 +594,7 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 		spin_unlock(&mdevice->lock);
 	} else {
 		spin_unlock(&mdevice->lock);
-		if (!dmirror_allocate_chunk(mdevice, &dpage))
+		if (dmirror_allocate_chunk(mdevice, &dpage))
 			goto error;
 	}
 
@@ -1244,10 +1276,8 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)
 	if (ret)
 		return ret;
 
-	/* Build a list of free ZONE_DEVICE private struct pages */
-	dmirror_allocate_chunk(mdevice, NULL);
-
-	return 0;
+	/* Build a list of free ZONE_DEVICE struct pages */
+	return dmirror_allocate_chunk(mdevice, NULL);
 }
 
 static void dmirror_device_remove(struct dmirror_device *mdevice)
@@ -1260,8 +1290,9 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
 				mdevice->devmem_chunks[i];
 
 			memunmap_pages(&devmem->pagemap);
-			release_mem_region(devmem->pagemap.range.start,
-					   range_len(&devmem->pagemap.range));
+			if (devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
+				release_mem_region(devmem->pagemap.range.start,
+						   range_len(&devmem->pagemap.range));
 			kfree(devmem);
 		}
 		kfree(mdevice->devmem_chunks);
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 17f842f1aa02..625f3690d086 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -68,6 +68,7 @@ enum {
 enum {
 	/* 0 is reserved to catch uninitialized type fields */
 	HMM_DMIRROR_MEMORY_DEVICE_PRIVATE = 1,
+	HMM_DMIRROR_MEMORY_DEVICE_COHERENT,
 };
 
 #endif /* _LIB_TEST_HMM_UAPI_H */
-- 
2.32.0

[PATCH v4 08/13] lib: test_hmm add module param for zone device type

[Alex Sierra]

In order to configure device coherent in test_hmm, two module parameters
should be passed, which correspond to the SP start address of each
device (2) spm_addr_dev0 & spm_addr_dev1. If no parameters are passed,
private device type is configured.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/test_hmm.c      | 73 ++++++++++++++++++++++++++++++++-------------
 lib/test_hmm_uapi.h |  1 +
 2 files changed, 53 insertions(+), 21 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 7a27584484ce..15747f70c5bc 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -37,6 +37,16 @@
 #define DEVMEM_CHUNK_SIZE		(256 * 1024 * 1024U)
 #define DEVMEM_CHUNKS_RESERVE		16
 
+static unsigned long spm_addr_dev0;
+module_param(spm_addr_dev0, long, 0644);
+MODULE_PARM_DESC(spm_addr_dev0,
+		"Specify start address for SPM (special purpose memory) used for device 0. By setting this Coherent device type will be used. Make sure spm_addr_dev1 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
+
+static unsigned long spm_addr_dev1;
+module_param(spm_addr_dev1, long, 0644);
+MODULE_PARM_DESC(spm_addr_dev1,
+		"Specify start address for SPM (special purpose memory) used for device 1. By setting this Coherent device type will be used. Make sure spm_addr_dev0 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
+
 static const struct dev_pagemap_ops dmirror_devmem_ops;
 static const struct mmu_interval_notifier_ops dmirror_min_ops;
 static dev_t dmirror_dev;
@@ -455,28 +465,44 @@ static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
 	return ret;
 }
 
-static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
+static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
 				   struct page **ppage)
 {
 	struct dmirror_chunk *devmem;
-	struct resource *res;
+	struct resource *res = NULL;
 	unsigned long pfn;
 	unsigned long pfn_first;
 	unsigned long pfn_last;
 	void *ptr;
+	int ret = -ENOMEM;
 
 	devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
 	if (!devmem)
-		return false;
+		return ret;
 
-	res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
-				      "hmm_dmirror");
-	if (IS_ERR(res))
+	switch (mdevice->zone_device_type) {
+	case HMM_DMIRROR_MEMORY_DEVICE_PRIVATE:
+		res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
+					      "hmm_dmirror");
+		if (IS_ERR_OR_NULL(res))
+			goto err_devmem;
+		devmem->pagemap.range.start = res->start;
+		devmem->pagemap.range.end = res->end;
+		devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
+		break;
+	case HMM_DMIRROR_MEMORY_DEVICE_COHERENT:
+		devmem->pagemap.range.start = (MINOR(mdevice->cdevice.dev) - 2) ?
+							spm_addr_dev0 :
+							spm_addr_dev1;
+		devmem->pagemap.range.end = devmem->pagemap.range.start +
+					    DEVMEM_CHUNK_SIZE - 1;
+		devmem->pagemap.type = MEMORY_DEVICE_COHERENT;
+		break;
+	default:
+		ret = -EINVAL;
 		goto err_devmem;
+	}
 
-	devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
-	devmem->pagemap.range.start = res->start;
-	devmem->pagemap.range.end = res->end;
 	devmem->pagemap.nr_range = 1;
 	devmem->pagemap.ops = &dmirror_devmem_ops;
 	devmem->pagemap.owner = mdevice;
@@ -497,10 +523,14 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
 		mdevice->devmem_capacity = new_capacity;
 		mdevice->devmem_chunks = new_chunks;
 	}
-
 	ptr = memremap_pages(&devmem->pagemap, numa_node_id());
-	if (IS_ERR(ptr))
+	if (IS_ERR_OR_NULL(ptr)) {
+		if (ptr)
+			ret = PTR_ERR(ptr);
+		else
+			ret = -EFAULT;
 		goto err_release;
+	}
 
 	devmem->mdevice = mdevice;
 	pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
@@ -529,15 +559,17 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
 	}
 	spin_unlock(&mdevice->lock);
 
-	return true;
+	return 0;
 
 err_release:
 	mutex_unlock(&mdevice->devmem_lock);
-	release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
+	if (res && devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
+		release_mem_region(devmem->pagemap.range.start,
+				   range_len(&devmem->pagemap.range));
 err_devmem:
 	kfree(devmem);
 
-	return false;
+	return ret;
 }
 
 static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
@@ -562,7 +594,7 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 		spin_unlock(&mdevice->lock);
 	} else {
 		spin_unlock(&mdevice->lock);
-		if (!dmirror_allocate_chunk(mdevice, &dpage))
+		if (dmirror_allocate_chunk(mdevice, &dpage))
 			goto error;
 	}
 
@@ -1244,10 +1276,8 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)
 	if (ret)
 		return ret;
 
-	/* Build a list of free ZONE_DEVICE private struct pages */
-	dmirror_allocate_chunk(mdevice, NULL);
-
-	return 0;
+	/* Build a list of free ZONE_DEVICE struct pages */
+	return dmirror_allocate_chunk(mdevice, NULL);
 }
 
 static void dmirror_device_remove(struct dmirror_device *mdevice)
@@ -1260,8 +1290,9 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
 				mdevice->devmem_chunks[i];
 
 			memunmap_pages(&devmem->pagemap);
-			release_mem_region(devmem->pagemap.range.start,
-					   range_len(&devmem->pagemap.range));
+			if (devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
+				release_mem_region(devmem->pagemap.range.start,
+						   range_len(&devmem->pagemap.range));
 			kfree(devmem);
 		}
 		kfree(mdevice->devmem_chunks);
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 17f842f1aa02..625f3690d086 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -68,6 +68,7 @@ enum {
 enum {
 	/* 0 is reserved to catch uninitialized type fields */
 	HMM_DMIRROR_MEMORY_DEVICE_PRIVATE = 1,
+	HMM_DMIRROR_MEMORY_DEVICE_COHERENT,
 };
 
 #endif /* _LIB_TEST_HMM_UAPI_H */
-- 
2.32.0

[PATCH v4 09/13] lib: add support for device coherent type in test_hmm

[Alex Sierra]

Device Coherent type uses device memory that is coherently accesible by
the CPU. This could be shown as SP (special purpose) memory range
at the BIOS-e820 memory enumeration. If no SP memory is supported in
system, this could be faked by setting CONFIG_EFI_FAKE_MEMMAP.

Currently, test_hmm only supports two different SP ranges of at least
256MB size. This could be specified in the kernel parameter variable
efi_fake_mem. Ex. Two SP ranges of 1GB starting at 0x100000000 &
0x140000000 physical address. Ex.
efi_fake_mem=1G@0x100000000:0x40000,1G@0x140000000:0x40000

Private and coherent device mirror instances can be created in the same
probed. This is done by passing the module parameters spm_addr_dev0 &
spm_addr_dev1. In this case, it will create four instances of
device_mirror. The first two correspond to private device type, the
last two to coherent type. Then, they can be easily accessed from user
space through /dev/hmm_mirror<num_device>. Usually num_device 0 and 1
are for private, and 2 and 3 for coherent types. If no module
parameters are passed, two instances of private type device_mirror will
be created only.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
---
 lib/test_hmm.c      | 253 +++++++++++++++++++++++++++++++++-----------
 lib/test_hmm_uapi.h |  15 ++-
 2 files changed, 202 insertions(+), 66 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 15747f70c5bc..361a026c5d21 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -32,11 +32,22 @@
 
 #include "test_hmm_uapi.h"
 
-#define DMIRROR_NDEVICES		2
+#define DMIRROR_NDEVICES		4
 #define DMIRROR_RANGE_FAULT_TIMEOUT	1000
 #define DEVMEM_CHUNK_SIZE		(256 * 1024 * 1024U)
 #define DEVMEM_CHUNKS_RESERVE		16
 
+/*
+ * For device_private pages, dpage is just a dummy struct page
+ * representing a piece of device memory. dmirror_devmem_alloc_page
+ * allocates a real system memory page as backing storage to fake a
+ * real device. zone_device_data points to that backing page. But
+ * for device_coherent memory, the struct page represents real
+ * physical CPU-accessible memory that we can use directly.
+ */
+#define BACKING_PAGE(page) (is_device_private_page((page)) ? \
+			   (page)->zone_device_data : (page))
+
 static unsigned long spm_addr_dev0;
 module_param(spm_addr_dev0, long, 0644);
 MODULE_PARM_DESC(spm_addr_dev0,
@@ -125,6 +136,21 @@ static int dmirror_bounce_init(struct dmirror_bounce *bounce,
 	return 0;
 }
 
+static bool dmirror_is_private_zone(struct dmirror_device *mdevice)
+{
+	return (mdevice->zone_device_type ==
+		HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ? true : false;
+}
+
+static enum migrate_vma_direction
+dmirror_select_device(struct dmirror *dmirror)
+{
+	return (dmirror->mdevice->zone_device_type ==
+		HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ?
+		MIGRATE_VMA_SELECT_DEVICE_PRIVATE :
+		MIGRATE_VMA_SELECT_DEVICE_COHERENT;
+}
+
 static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
 {
 	vfree(bounce->ptr);
@@ -575,16 +601,19 @@ static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
 static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 {
 	struct page *dpage = NULL;
-	struct page *rpage;
+	struct page *rpage = NULL;
 
 	/*
-	 * This is a fake device so we alloc real system memory to store
-	 * our device memory.
+	 * For ZONE_DEVICE private type, this is a fake device so we allocate
+	 * real system memory to store our device memory.
+	 * For ZONE_DEVICE coherent type we use the actual dpage to store the
+	 * data and ignore rpage.
 	 */
-	rpage = alloc_page(GFP_HIGHUSER);
-	if (!rpage)
-		return NULL;
-
+	if (dmirror_is_private_zone(mdevice)) {
+		rpage = alloc_page(GFP_HIGHUSER);
+		if (!rpage)
+			return NULL;
+	}
 	spin_lock(&mdevice->lock);
 
 	if (mdevice->free_pages) {
@@ -603,7 +632,8 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 	return dpage;
 
 error:
-	__free_page(rpage);
+	if (rpage)
+		__free_page(rpage);
 	return NULL;
 }
 
@@ -629,12 +659,16 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
 		 * unallocated pte_none() or read-only zero page.
 		 */
 		spage = migrate_pfn_to_page(*src);
+		if (WARN(spage && is_zone_device_page(spage),
+		     "page already in device spage pfn: 0x%lx\n",
+		     page_to_pfn(spage)))
+			continue;
 
 		dpage = dmirror_devmem_alloc_page(mdevice);
 		if (!dpage)
 			continue;
 
-		rpage = dpage->zone_device_data;
+		rpage = BACKING_PAGE(dpage);
 		if (spage)
 			copy_highpage(rpage, spage);
 		else
@@ -648,6 +682,8 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
 		 */
 		rpage->zone_device_data = dmirror;
 
+		pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
+			 page_to_pfn(spage), page_to_pfn(dpage));
 		*dst = migrate_pfn(page_to_pfn(dpage));
 		if ((*src & MIGRATE_PFN_WRITE) ||
 		    (!spage && args->vma->vm_flags & VM_WRITE))
@@ -725,11 +761,7 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
 		if (!dpage)
 			continue;
 
-		/*
-		 * Store the page that holds the data so the page table
-		 * doesn't have to deal with ZONE_DEVICE private pages.
-		 */
-		entry = dpage->zone_device_data;
+		entry = BACKING_PAGE(dpage);
 		if (*dst & MIGRATE_PFN_WRITE)
 			entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
 		entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
@@ -809,15 +841,126 @@ static int dmirror_exclusive(struct dmirror *dmirror,
 	return ret;
 }
 
-static int dmirror_migrate(struct dmirror *dmirror,
-			   struct hmm_dmirror_cmd *cmd)
+static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
+						      struct dmirror *dmirror)
+{
+	const unsigned long *src = args->src;
+	unsigned long *dst = args->dst;
+	unsigned long start = args->start;
+	unsigned long end = args->end;
+	unsigned long addr;
+
+	for (addr = start; addr < end; addr += PAGE_SIZE,
+				       src++, dst++) {
+		struct page *dpage, *spage;
+
+		spage = migrate_pfn_to_page(*src);
+		if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
+			continue;
+
+		if (WARN_ON(!is_device_private_page(spage) &&
+			    !is_device_coherent_page(spage)))
+			continue;
+		spage = BACKING_PAGE(spage);
+		dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
+		if (!dpage)
+			continue;
+		pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
+			 page_to_pfn(spage), page_to_pfn(dpage));
+
+		lock_page(dpage);
+		xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
+		copy_highpage(dpage, spage);
+		*dst = migrate_pfn(page_to_pfn(dpage));
+		if (*src & MIGRATE_PFN_WRITE)
+			*dst |= MIGRATE_PFN_WRITE;
+	}
+	return 0;
+}
+
+static unsigned long
+dmirror_successful_migrated_pages(struct migrate_vma *migrate)
+{
+	unsigned long cpages = 0;
+	unsigned long i;
+
+	for (i = 0; i < migrate->npages; i++) {
+		if (migrate->src[i] & MIGRATE_PFN_VALID &&
+		    migrate->src[i] & MIGRATE_PFN_MIGRATE)
+			cpages++;
+	}
+	return cpages;
+}
+
+static int dmirror_migrate_to_system(struct dmirror *dmirror,
+				     struct hmm_dmirror_cmd *cmd)
 {
 	unsigned long start, end, addr;
 	unsigned long size = cmd->npages << PAGE_SHIFT;
 	struct mm_struct *mm = dmirror->notifier.mm;
 	struct vm_area_struct *vma;
-	unsigned long src_pfns[64];
-	unsigned long dst_pfns[64];
+	unsigned long src_pfns[64] = { 0 };
+	unsigned long dst_pfns[64] = { 0 };
+	struct migrate_vma args;
+	unsigned long next;
+	int ret;
+
+	start = cmd->addr;
+	end = start + size;
+	if (end < start)
+		return -EINVAL;
+
+	/* Since the mm is for the mirrored process, get a reference first. */
+	if (!mmget_not_zero(mm))
+		return -EINVAL;
+
+	cmd->cpages = 0;
+	mmap_read_lock(mm);
+	for (addr = start; addr < end; addr = next) {
+		vma = vma_lookup(mm, addr);
+		if (!vma || !(vma->vm_flags & VM_READ)) {
+			ret = -EINVAL;
+			goto out;
+		}
+		next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
+		if (next > vma->vm_end)
+			next = vma->vm_end;
+
+		args.vma = vma;
+		args.src = src_pfns;
+		args.dst = dst_pfns;
+		args.start = addr;
+		args.end = next;
+		args.pgmap_owner = dmirror->mdevice;
+		args.flags = dmirror_select_device(dmirror);
+
+		ret = migrate_vma_setup(&args);
+		if (ret)
+			goto out;
+
+		pr_debug("Migrating from device mem to sys mem\n");
+		dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
+
+		migrate_vma_pages(&args);
+		cmd->cpages += dmirror_successful_migrated_pages(&args);
+		migrate_vma_finalize(&args);
+	}
+out:
+	mmap_read_unlock(mm);
+	mmput(mm);
+
+	return ret;
+}
+
+static int dmirror_migrate_to_device(struct dmirror *dmirror,
+				struct hmm_dmirror_cmd *cmd)
+{
+	unsigned long start, end, addr;
+	unsigned long size = cmd->npages << PAGE_SHIFT;
+	struct mm_struct *mm = dmirror->notifier.mm;
+	struct vm_area_struct *vma;
+	unsigned long src_pfns[64] = { 0 };
+	unsigned long dst_pfns[64] = { 0 };
 	struct dmirror_bounce bounce;
 	struct migrate_vma args;
 	unsigned long next;
@@ -854,6 +997,7 @@ static int dmirror_migrate(struct dmirror *dmirror,
 		if (ret)
 			goto out;
 
+		pr_debug("Migrating from sys mem to device mem\n");
 		dmirror_migrate_alloc_and_copy(&args, dmirror);
 		migrate_vma_pages(&args);
 		dmirror_migrate_finalize_and_map(&args, dmirror);
@@ -862,7 +1006,10 @@ static int dmirror_migrate(struct dmirror *dmirror,
 	mmap_read_unlock(mm);
 	mmput(mm);
 
-	/* Return the migrated data for verification. */
+	/*
+	 * Return the migrated data for verification.
+	 * Only for pages in device zone
+	 */
 	ret = dmirror_bounce_init(&bounce, start, size);
 	if (ret)
 		return ret;
@@ -905,6 +1052,12 @@ static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
 			*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
 		else
 			*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
+	} else if (is_device_coherent_page(page)) {
+		/* Is the page migrated to this device or some other? */
+		if (dmirror->mdevice == dmirror_page_to_device(page))
+			*perm = HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL;
+		else
+			*perm = HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE;
 	} else if (is_zero_pfn(page_to_pfn(page)))
 		*perm = HMM_DMIRROR_PROT_ZERO;
 	else
@@ -1101,8 +1254,12 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
 		ret = dmirror_write(dmirror, &cmd);
 		break;
 
-	case HMM_DMIRROR_MIGRATE:
-		ret = dmirror_migrate(dmirror, &cmd);
+	case HMM_DMIRROR_MIGRATE_TO_DEV:
+		ret = dmirror_migrate_to_device(dmirror, &cmd);
+		break;
+
+	case HMM_DMIRROR_MIGRATE_TO_SYS:
+		ret = dmirror_migrate_to_system(dmirror, &cmd);
 		break;
 
 	case HMM_DMIRROR_EXCLUSIVE:
@@ -1167,14 +1324,13 @@ static const struct file_operations dmirror_fops = {
 
 static void dmirror_devmem_free(struct page *page)
 {
-	struct page *rpage = page->zone_device_data;
+	struct page *rpage = BACKING_PAGE(page);
 	struct dmirror_device *mdevice;
 
-	if (rpage)
+	if (rpage != page)
 		__free_page(rpage);
 
 	mdevice = dmirror_page_to_device(page);
-
 	spin_lock(&mdevice->lock);
 	mdevice->cfree++;
 	page->zone_device_data = mdevice->free_pages;
@@ -1182,43 +1338,11 @@ static void dmirror_devmem_free(struct page *page)
 	spin_unlock(&mdevice->lock);
 }
 
-static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
-						      struct dmirror *dmirror)
-{
-	const unsigned long *src = args->src;
-	unsigned long *dst = args->dst;
-	unsigned long start = args->start;
-	unsigned long end = args->end;
-	unsigned long addr;
-
-	for (addr = start; addr < end; addr += PAGE_SIZE,
-				       src++, dst++) {
-		struct page *dpage, *spage;
-
-		spage = migrate_pfn_to_page(*src);
-		if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
-			continue;
-		spage = spage->zone_device_data;
-
-		dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
-		if (!dpage)
-			continue;
-
-		lock_page(dpage);
-		xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
-		copy_highpage(dpage, spage);
-		*dst = migrate_pfn(page_to_pfn(dpage));
-		if (*src & MIGRATE_PFN_WRITE)
-			*dst |= MIGRATE_PFN_WRITE;
-	}
-	return 0;
-}
-
 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 {
 	struct migrate_vma args;
-	unsigned long src_pfns;
-	unsigned long dst_pfns;
+	unsigned long src_pfns = 0;
+	unsigned long dst_pfns = 0;
 	struct page *rpage;
 	struct dmirror *dmirror;
 	vm_fault_t ret;
@@ -1238,7 +1362,7 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 	args.src = &src_pfns;
 	args.dst = &dst_pfns;
 	args.pgmap_owner = dmirror->mdevice;
-	args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
+	args.flags = dmirror_select_device(dmirror);
 
 	if (migrate_vma_setup(&args))
 		return VM_FAULT_SIGBUS;
@@ -1317,6 +1441,12 @@ static int __init hmm_dmirror_init(void)
 				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
 	dmirror_devices[ndevices++].zone_device_type =
 				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
+	if (spm_addr_dev0 && spm_addr_dev1) {
+		dmirror_devices[ndevices++].zone_device_type =
+					HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
+		dmirror_devices[ndevices++].zone_device_type =
+					HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
+	}
 	for (id = 0; id < ndevices; id++) {
 		ret = dmirror_device_init(dmirror_devices + id, id);
 		if (ret)
@@ -1339,7 +1469,8 @@ static void __exit hmm_dmirror_exit(void)
 	int id;
 
 	for (id = 0; id < DMIRROR_NDEVICES; id++)
-		dmirror_device_remove(dmirror_devices + id);
+		if (dmirror_devices[id].zone_device_type)
+			dmirror_device_remove(dmirror_devices + id);
 	unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
 }
 
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 625f3690d086..e190b2ab6f19 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -33,11 +33,12 @@ struct hmm_dmirror_cmd {
 /* Expose the address space of the calling process through hmm device file */
 #define HMM_DMIRROR_READ		_IOWR('H', 0x00, struct hmm_dmirror_cmd)
 #define HMM_DMIRROR_WRITE		_IOWR('H', 0x01, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_MIGRATE		_IOWR('H', 0x02, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x03, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x05, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_MIGRATE_TO_DEV	_IOWR('H', 0x02, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_MIGRATE_TO_SYS	_IOWR('H', 0x03, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x05, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x07, struct hmm_dmirror_cmd)
 
 /*
  * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
@@ -52,6 +53,8 @@ struct hmm_dmirror_cmd {
  *					device the ioctl() is made
  * HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE: Migrated device private page on some
  *					other device
+ * HMM_DMIRROR_PROT_DEV_COHERENT: Migrate device coherent page on the device
+ *				  the ioctl() is made
  */
 enum {
 	HMM_DMIRROR_PROT_ERROR			= 0xFF,
@@ -63,6 +66,8 @@ enum {
 	HMM_DMIRROR_PROT_ZERO			= 0x10,
 	HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL	= 0x20,
 	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
+	HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL	= 0x40,
+	HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE	= 0x50,
 };
 
 enum {
-- 
2.32.0

[PATCH v4 09/13] lib: add support for device coherent type in test_hmm

[Alex Sierra]

Device Coherent type uses device memory that is coherently accesible by
the CPU. This could be shown as SP (special purpose) memory range
at the BIOS-e820 memory enumeration. If no SP memory is supported in
system, this could be faked by setting CONFIG_EFI_FAKE_MEMMAP.

Currently, test_hmm only supports two different SP ranges of at least
256MB size. This could be specified in the kernel parameter variable
efi_fake_mem. Ex. Two SP ranges of 1GB starting at 0x100000000 &
0x140000000 physical address. Ex.
efi_fake_mem=1G@0x100000000:0x40000,1G@0x140000000:0x40000

Private and coherent device mirror instances can be created in the same
probed. This is done by passing the module parameters spm_addr_dev0 &
spm_addr_dev1. In this case, it will create four instances of
device_mirror. The first two correspond to private device type, the
last two to coherent type. Then, they can be easily accessed from user
space through /dev/hmm_mirror<num_device>. Usually num_device 0 and 1
are for private, and 2 and 3 for coherent types. If no module
parameters are passed, two instances of private type device_mirror will
be created only.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
---
 lib/test_hmm.c      | 253 +++++++++++++++++++++++++++++++++-----------
 lib/test_hmm_uapi.h |  15 ++-
 2 files changed, 202 insertions(+), 66 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 15747f70c5bc..361a026c5d21 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -32,11 +32,22 @@
 
 #include "test_hmm_uapi.h"
 
-#define DMIRROR_NDEVICES		2
+#define DMIRROR_NDEVICES		4
 #define DMIRROR_RANGE_FAULT_TIMEOUT	1000
 #define DEVMEM_CHUNK_SIZE		(256 * 1024 * 1024U)
 #define DEVMEM_CHUNKS_RESERVE		16
 
+/*
+ * For device_private pages, dpage is just a dummy struct page
+ * representing a piece of device memory. dmirror_devmem_alloc_page
+ * allocates a real system memory page as backing storage to fake a
+ * real device. zone_device_data points to that backing page. But
+ * for device_coherent memory, the struct page represents real
+ * physical CPU-accessible memory that we can use directly.
+ */
+#define BACKING_PAGE(page) (is_device_private_page((page)) ? \
+			   (page)->zone_device_data : (page))
+
 static unsigned long spm_addr_dev0;
 module_param(spm_addr_dev0, long, 0644);
 MODULE_PARM_DESC(spm_addr_dev0,
@@ -125,6 +136,21 @@ static int dmirror_bounce_init(struct dmirror_bounce *bounce,
 	return 0;
 }
 
+static bool dmirror_is_private_zone(struct dmirror_device *mdevice)
+{
+	return (mdevice->zone_device_type ==
+		HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ? true : false;
+}
+
+static enum migrate_vma_direction
+dmirror_select_device(struct dmirror *dmirror)
+{
+	return (dmirror->mdevice->zone_device_type ==
+		HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ?
+		MIGRATE_VMA_SELECT_DEVICE_PRIVATE :
+		MIGRATE_VMA_SELECT_DEVICE_COHERENT;
+}
+
 static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
 {
 	vfree(bounce->ptr);
@@ -575,16 +601,19 @@ static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
 static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 {
 	struct page *dpage = NULL;
-	struct page *rpage;
+	struct page *rpage = NULL;
 
 	/*
-	 * This is a fake device so we alloc real system memory to store
-	 * our device memory.
+	 * For ZONE_DEVICE private type, this is a fake device so we allocate
+	 * real system memory to store our device memory.
+	 * For ZONE_DEVICE coherent type we use the actual dpage to store the
+	 * data and ignore rpage.
 	 */
-	rpage = alloc_page(GFP_HIGHUSER);
-	if (!rpage)
-		return NULL;
-
+	if (dmirror_is_private_zone(mdevice)) {
+		rpage = alloc_page(GFP_HIGHUSER);
+		if (!rpage)
+			return NULL;
+	}
 	spin_lock(&mdevice->lock);
 
 	if (mdevice->free_pages) {
@@ -603,7 +632,8 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 	return dpage;
 
 error:
-	__free_page(rpage);
+	if (rpage)
+		__free_page(rpage);
 	return NULL;
 }
 
@@ -629,12 +659,16 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
 		 * unallocated pte_none() or read-only zero page.
 		 */
 		spage = migrate_pfn_to_page(*src);
+		if (WARN(spage && is_zone_device_page(spage),
+		     "page already in device spage pfn: 0x%lx\n",
+		     page_to_pfn(spage)))
+			continue;
 
 		dpage = dmirror_devmem_alloc_page(mdevice);
 		if (!dpage)
 			continue;
 
-		rpage = dpage->zone_device_data;
+		rpage = BACKING_PAGE(dpage);
 		if (spage)
 			copy_highpage(rpage, spage);
 		else
@@ -648,6 +682,8 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
 		 */
 		rpage->zone_device_data = dmirror;
 
+		pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
+			 page_to_pfn(spage), page_to_pfn(dpage));
 		*dst = migrate_pfn(page_to_pfn(dpage));
 		if ((*src & MIGRATE_PFN_WRITE) ||
 		    (!spage && args->vma->vm_flags & VM_WRITE))
@@ -725,11 +761,7 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
 		if (!dpage)
 			continue;
 
-		/*
-		 * Store the page that holds the data so the page table
-		 * doesn't have to deal with ZONE_DEVICE private pages.
-		 */
-		entry = dpage->zone_device_data;
+		entry = BACKING_PAGE(dpage);
 		if (*dst & MIGRATE_PFN_WRITE)
 			entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
 		entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
@@ -809,15 +841,126 @@ static int dmirror_exclusive(struct dmirror *dmirror,
 	return ret;
 }
 
-static int dmirror_migrate(struct dmirror *dmirror,
-			   struct hmm_dmirror_cmd *cmd)
+static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
+						      struct dmirror *dmirror)
+{
+	const unsigned long *src = args->src;
+	unsigned long *dst = args->dst;
+	unsigned long start = args->start;
+	unsigned long end = args->end;
+	unsigned long addr;
+
+	for (addr = start; addr < end; addr += PAGE_SIZE,
+				       src++, dst++) {
+		struct page *dpage, *spage;
+
+		spage = migrate_pfn_to_page(*src);
+		if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
+			continue;
+
+		if (WARN_ON(!is_device_private_page(spage) &&
+			    !is_device_coherent_page(spage)))
+			continue;
+		spage = BACKING_PAGE(spage);
+		dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
+		if (!dpage)
+			continue;
+		pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
+			 page_to_pfn(spage), page_to_pfn(dpage));
+
+		lock_page(dpage);
+		xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
+		copy_highpage(dpage, spage);
+		*dst = migrate_pfn(page_to_pfn(dpage));
+		if (*src & MIGRATE_PFN_WRITE)
+			*dst |= MIGRATE_PFN_WRITE;
+	}
+	return 0;
+}
+
+static unsigned long
+dmirror_successful_migrated_pages(struct migrate_vma *migrate)
+{
+	unsigned long cpages = 0;
+	unsigned long i;
+
+	for (i = 0; i < migrate->npages; i++) {
+		if (migrate->src[i] & MIGRATE_PFN_VALID &&
+		    migrate->src[i] & MIGRATE_PFN_MIGRATE)
+			cpages++;
+	}
+	return cpages;
+}
+
+static int dmirror_migrate_to_system(struct dmirror *dmirror,
+				     struct hmm_dmirror_cmd *cmd)
 {
 	unsigned long start, end, addr;
 	unsigned long size = cmd->npages << PAGE_SHIFT;
 	struct mm_struct *mm = dmirror->notifier.mm;
 	struct vm_area_struct *vma;
-	unsigned long src_pfns[64];
-	unsigned long dst_pfns[64];
+	unsigned long src_pfns[64] = { 0 };
+	unsigned long dst_pfns[64] = { 0 };
+	struct migrate_vma args;
+	unsigned long next;
+	int ret;
+
+	start = cmd->addr;
+	end = start + size;
+	if (end < start)
+		return -EINVAL;
+
+	/* Since the mm is for the mirrored process, get a reference first. */
+	if (!mmget_not_zero(mm))
+		return -EINVAL;
+
+	cmd->cpages = 0;
+	mmap_read_lock(mm);
+	for (addr = start; addr < end; addr = next) {
+		vma = vma_lookup(mm, addr);
+		if (!vma || !(vma->vm_flags & VM_READ)) {
+			ret = -EINVAL;
+			goto out;
+		}
+		next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
+		if (next > vma->vm_end)
+			next = vma->vm_end;
+
+		args.vma = vma;
+		args.src = src_pfns;
+		args.dst = dst_pfns;
+		args.start = addr;
+		args.end = next;
+		args.pgmap_owner = dmirror->mdevice;
+		args.flags = dmirror_select_device(dmirror);
+
+		ret = migrate_vma_setup(&args);
+		if (ret)
+			goto out;
+
+		pr_debug("Migrating from device mem to sys mem\n");
+		dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
+
+		migrate_vma_pages(&args);
+		cmd->cpages += dmirror_successful_migrated_pages(&args);
+		migrate_vma_finalize(&args);
+	}
+out:
+	mmap_read_unlock(mm);
+	mmput(mm);
+
+	return ret;
+}
+
+static int dmirror_migrate_to_device(struct dmirror *dmirror,
+				struct hmm_dmirror_cmd *cmd)
+{
+	unsigned long start, end, addr;
+	unsigned long size = cmd->npages << PAGE_SHIFT;
+	struct mm_struct *mm = dmirror->notifier.mm;
+	struct vm_area_struct *vma;
+	unsigned long src_pfns[64] = { 0 };
+	unsigned long dst_pfns[64] = { 0 };
 	struct dmirror_bounce bounce;
 	struct migrate_vma args;
 	unsigned long next;
@@ -854,6 +997,7 @@ static int dmirror_migrate(struct dmirror *dmirror,
 		if (ret)
 			goto out;
 
+		pr_debug("Migrating from sys mem to device mem\n");
 		dmirror_migrate_alloc_and_copy(&args, dmirror);
 		migrate_vma_pages(&args);
 		dmirror_migrate_finalize_and_map(&args, dmirror);
@@ -862,7 +1006,10 @@ static int dmirror_migrate(struct dmirror *dmirror,
 	mmap_read_unlock(mm);
 	mmput(mm);
 
-	/* Return the migrated data for verification. */
+	/*
+	 * Return the migrated data for verification.
+	 * Only for pages in device zone
+	 */
 	ret = dmirror_bounce_init(&bounce, start, size);
 	if (ret)
 		return ret;
@@ -905,6 +1052,12 @@ static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
 			*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
 		else
 			*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
+	} else if (is_device_coherent_page(page)) {
+		/* Is the page migrated to this device or some other? */
+		if (dmirror->mdevice == dmirror_page_to_device(page))
+			*perm = HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL;
+		else
+			*perm = HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE;
 	} else if (is_zero_pfn(page_to_pfn(page)))
 		*perm = HMM_DMIRROR_PROT_ZERO;
 	else
@@ -1101,8 +1254,12 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
 		ret = dmirror_write(dmirror, &cmd);
 		break;
 
-	case HMM_DMIRROR_MIGRATE:
-		ret = dmirror_migrate(dmirror, &cmd);
+	case HMM_DMIRROR_MIGRATE_TO_DEV:
+		ret = dmirror_migrate_to_device(dmirror, &cmd);
+		break;
+
+	case HMM_DMIRROR_MIGRATE_TO_SYS:
+		ret = dmirror_migrate_to_system(dmirror, &cmd);
 		break;
 
 	case HMM_DMIRROR_EXCLUSIVE:
@@ -1167,14 +1324,13 @@ static const struct file_operations dmirror_fops = {
 
 static void dmirror_devmem_free(struct page *page)
 {
-	struct page *rpage = page->zone_device_data;
+	struct page *rpage = BACKING_PAGE(page);
 	struct dmirror_device *mdevice;
 
-	if (rpage)
+	if (rpage != page)
 		__free_page(rpage);
 
 	mdevice = dmirror_page_to_device(page);
-
 	spin_lock(&mdevice->lock);
 	mdevice->cfree++;
 	page->zone_device_data = mdevice->free_pages;
@@ -1182,43 +1338,11 @@ static void dmirror_devmem_free(struct page *page)
 	spin_unlock(&mdevice->lock);
 }
 
-static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
-						      struct dmirror *dmirror)
-{
-	const unsigned long *src = args->src;
-	unsigned long *dst = args->dst;
-	unsigned long start = args->start;
-	unsigned long end = args->end;
-	unsigned long addr;
-
-	for (addr = start; addr < end; addr += PAGE_SIZE,
-				       src++, dst++) {
-		struct page *dpage, *spage;
-
-		spage = migrate_pfn_to_page(*src);
-		if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
-			continue;
-		spage = spage->zone_device_data;
-
-		dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
-		if (!dpage)
-			continue;
-
-		lock_page(dpage);
-		xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
-		copy_highpage(dpage, spage);
-		*dst = migrate_pfn(page_to_pfn(dpage));
-		if (*src & MIGRATE_PFN_WRITE)
-			*dst |= MIGRATE_PFN_WRITE;
-	}
-	return 0;
-}
-
 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 {
 	struct migrate_vma args;
-	unsigned long src_pfns;
-	unsigned long dst_pfns;
+	unsigned long src_pfns = 0;
+	unsigned long dst_pfns = 0;
 	struct page *rpage;
 	struct dmirror *dmirror;
 	vm_fault_t ret;
@@ -1238,7 +1362,7 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
 	args.src = &src_pfns;
 	args.dst = &dst_pfns;
 	args.pgmap_owner = dmirror->mdevice;
-	args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
+	args.flags = dmirror_select_device(dmirror);
 
 	if (migrate_vma_setup(&args))
 		return VM_FAULT_SIGBUS;
@@ -1317,6 +1441,12 @@ static int __init hmm_dmirror_init(void)
 				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
 	dmirror_devices[ndevices++].zone_device_type =
 				HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
+	if (spm_addr_dev0 && spm_addr_dev1) {
+		dmirror_devices[ndevices++].zone_device_type =
+					HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
+		dmirror_devices[ndevices++].zone_device_type =
+					HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
+	}
 	for (id = 0; id < ndevices; id++) {
 		ret = dmirror_device_init(dmirror_devices + id, id);
 		if (ret)
@@ -1339,7 +1469,8 @@ static void __exit hmm_dmirror_exit(void)
 	int id;
 
 	for (id = 0; id < DMIRROR_NDEVICES; id++)
-		dmirror_device_remove(dmirror_devices + id);
+		if (dmirror_devices[id].zone_device_type)
+			dmirror_device_remove(dmirror_devices + id);
 	unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
 }
 
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 625f3690d086..e190b2ab6f19 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -33,11 +33,12 @@ struct hmm_dmirror_cmd {
 /* Expose the address space of the calling process through hmm device file */
 #define HMM_DMIRROR_READ		_IOWR('H', 0x00, struct hmm_dmirror_cmd)
 #define HMM_DMIRROR_WRITE		_IOWR('H', 0x01, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_MIGRATE		_IOWR('H', 0x02, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x03, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x05, struct hmm_dmirror_cmd)
-#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_MIGRATE_TO_DEV	_IOWR('H', 0x02, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_MIGRATE_TO_SYS	_IOWR('H', 0x03, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_SNAPSHOT		_IOWR('H', 0x04, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_EXCLUSIVE		_IOWR('H', 0x05, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_CHECK_EXCLUSIVE	_IOWR('H', 0x06, struct hmm_dmirror_cmd)
+#define HMM_DMIRROR_GET_MEM_DEV_TYPE	_IOWR('H', 0x07, struct hmm_dmirror_cmd)
 
 /*
  * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
@@ -52,6 +53,8 @@ struct hmm_dmirror_cmd {
  *					device the ioctl() is made
  * HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE: Migrated device private page on some
  *					other device
+ * HMM_DMIRROR_PROT_DEV_COHERENT: Migrate device coherent page on the device
+ *				  the ioctl() is made
  */
 enum {
 	HMM_DMIRROR_PROT_ERROR			= 0xFF,
@@ -63,6 +66,8 @@ enum {
 	HMM_DMIRROR_PROT_ZERO			= 0x10,
 	HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL	= 0x20,
 	HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE	= 0x30,
+	HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL	= 0x40,
+	HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE	= 0x50,
 };
 
 enum {
-- 
2.32.0

[PATCH v4 10/13] tools: update hmm-test to support device coherent type

[Alex Sierra]

Test cases such as migrate_fault and migrate_multiple, were modified to
explicit migrate from device to sys memory without the need of page
faults, when using device coherent type.

Snapshot test case updated to read memory device type first and based
on that, get the proper returned results migrate_ping_pong test case
added to test explicit migration from device to sys memory for both
private and coherent zone types.

Helpers to migrate from device to sys memory and vicerversa
were also added.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 tools/testing/selftests/vm/hmm-tests.c | 123 ++++++++++++++++++++-----
 1 file changed, 102 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 203323967b50..84ec8c4a1dc7 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -44,6 +44,14 @@ struct hmm_buffer {
 	int		fd;
 	uint64_t	cpages;
 	uint64_t	faults;
+	int		zone_device_type;
+};
+
+enum {
+	HMM_PRIVATE_DEVICE_ONE,
+	HMM_PRIVATE_DEVICE_TWO,
+	HMM_COHERENCE_DEVICE_ONE,
+	HMM_COHERENCE_DEVICE_TWO,
 };
 
 #define TWOMEG		(1 << 21)
@@ -60,6 +68,21 @@ FIXTURE(hmm)
 	unsigned int	page_shift;
 };
 
+FIXTURE_VARIANT(hmm)
+{
+	int     device_number;
+};
+
+FIXTURE_VARIANT_ADD(hmm, hmm_device_private)
+{
+	.device_number = HMM_PRIVATE_DEVICE_ONE,
+};
+
+FIXTURE_VARIANT_ADD(hmm, hmm_device_coherent)
+{
+	.device_number = HMM_COHERENCE_DEVICE_ONE,
+};
+
 FIXTURE(hmm2)
 {
 	int		fd0;
@@ -68,6 +91,24 @@ FIXTURE(hmm2)
 	unsigned int	page_shift;
 };
 
+FIXTURE_VARIANT(hmm2)
+{
+	int     device_number0;
+	int     device_number1;
+};
+
+FIXTURE_VARIANT_ADD(hmm2, hmm2_device_private)
+{
+	.device_number0 = HMM_PRIVATE_DEVICE_ONE,
+	.device_number1 = HMM_PRIVATE_DEVICE_TWO,
+};
+
+FIXTURE_VARIANT_ADD(hmm2, hmm2_device_coherent)
+{
+	.device_number0 = HMM_COHERENCE_DEVICE_ONE,
+	.device_number1 = HMM_COHERENCE_DEVICE_TWO,
+};
+
 static int hmm_open(int unit)
 {
 	char pathname[HMM_PATH_MAX];
@@ -81,12 +122,19 @@ static int hmm_open(int unit)
 	return fd;
 }
 
+static bool hmm_is_coherent_type(int dev_num)
+{
+	return (dev_num >= HMM_COHERENCE_DEVICE_ONE);
+}
+
 FIXTURE_SETUP(hmm)
 {
 	self->page_size = sysconf(_SC_PAGE_SIZE);
 	self->page_shift = ffs(self->page_size) - 1;
 
-	self->fd = hmm_open(0);
+	self->fd = hmm_open(variant->device_number);
+	if (self->fd < 0 && hmm_is_coherent_type(variant->device_number))
+		SKIP(exit(0), "DEVICE_COHERENT not available");
 	ASSERT_GE(self->fd, 0);
 }
 
@@ -95,9 +143,11 @@ FIXTURE_SETUP(hmm2)
 	self->page_size = sysconf(_SC_PAGE_SIZE);
 	self->page_shift = ffs(self->page_size) - 1;
 
-	self->fd0 = hmm_open(0);
+	self->fd0 = hmm_open(variant->device_number0);
+	if (self->fd0 < 0 && hmm_is_coherent_type(variant->device_number0))
+		SKIP(exit(0), "DEVICE_COHERENT not available");
 	ASSERT_GE(self->fd0, 0);
-	self->fd1 = hmm_open(1);
+	self->fd1 = hmm_open(variant->device_number1);
 	ASSERT_GE(self->fd1, 0);
 }
 
@@ -144,6 +194,7 @@ static int hmm_dmirror_cmd(int fd,
 	}
 	buffer->cpages = cmd.cpages;
 	buffer->faults = cmd.faults;
+	buffer->zone_device_type = cmd.zone_device_type;
 
 	return 0;
 }
@@ -211,6 +262,20 @@ static void hmm_nanosleep(unsigned int n)
 	nanosleep(&t, NULL);
 }
 
+static int hmm_migrate_sys_to_dev(int fd,
+				   struct hmm_buffer *buffer,
+				   unsigned long npages)
+{
+	return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_DEV, buffer, npages);
+}
+
+static int hmm_migrate_dev_to_sys(int fd,
+				   struct hmm_buffer *buffer,
+				   unsigned long npages)
+{
+	return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_SYS, buffer, npages);
+}
+
 /*
  * Simple NULL test of device open/close.
  */
@@ -875,7 +940,7 @@ TEST_F(hmm, migrate)
 		ptr[i] = i;
 
 	/* Migrate memory to device. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, npages);
 
@@ -923,7 +988,7 @@ TEST_F(hmm, migrate_fault)
 		ptr[i] = i;
 
 	/* Migrate memory to device. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, npages);
 
@@ -936,7 +1001,7 @@ TEST_F(hmm, migrate_fault)
 		ASSERT_EQ(ptr[i], i);
 
 	/* Migrate memory to the device again. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, npages);
 
@@ -976,7 +1041,7 @@ TEST_F(hmm, migrate_shared)
 	ASSERT_NE(buffer->ptr, MAP_FAILED);
 
 	/* Migrate memory to device. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, -ENOENT);
 
 	hmm_buffer_free(buffer);
@@ -1015,7 +1080,7 @@ TEST_F(hmm2, migrate_mixed)
 	p = buffer->ptr;
 
 	/* Migrating a protected area should be an error. */
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, npages);
 	ASSERT_EQ(ret, -EINVAL);
 
 	/* Punch a hole after the first page address. */
@@ -1023,7 +1088,7 @@ TEST_F(hmm2, migrate_mixed)
 	ASSERT_EQ(ret, 0);
 
 	/* We expect an error if the vma doesn't cover the range. */
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, 3);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 3);
 	ASSERT_EQ(ret, -EINVAL);
 
 	/* Page 2 will be a read-only zero page. */
@@ -1055,13 +1120,13 @@ TEST_F(hmm2, migrate_mixed)
 
 	/* Now try to migrate pages 2-5 to device 1. */
 	buffer->ptr = p + 2 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, 4);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 4);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, 4);
 
 	/* Page 5 won't be migrated to device 0 because it's on device 1. */
 	buffer->ptr = p + 5 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_MIGRATE, buffer, 1);
+	ret = hmm_migrate_sys_to_dev(self->fd0, buffer, 1);
 	ASSERT_EQ(ret, -ENOENT);
 	buffer->ptr = p;
 
@@ -1070,8 +1135,12 @@ TEST_F(hmm2, migrate_mixed)
 }
 
 /*
- * Migrate anonymous memory to device private memory and fault it back to system
- * memory multiple times.
+ * Migrate anonymous memory to device memory and back to system memory
+ * multiple times. In case of private zone configuration, this is done
+ * through fault pages accessed by CPU. In case of coherent zone configuration,
+ * the pages from the device should be explicitly migrated back to system memory.
+ * The reason is Coherent device zone has coherent access by CPU, therefore
+ * it will not generate any page fault.
  */
 TEST_F(hmm, migrate_multiple)
 {
@@ -1107,8 +1176,7 @@ TEST_F(hmm, migrate_multiple)
 			ptr[i] = i;
 
 		/* Migrate memory to device. */
-		ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer,
-				      npages);
+		ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 		ASSERT_EQ(ret, 0);
 		ASSERT_EQ(buffer->cpages, npages);
 
@@ -1116,7 +1184,13 @@ TEST_F(hmm, migrate_multiple)
 		for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
 			ASSERT_EQ(ptr[i], i);
 
-		/* Fault pages back to system memory and check them. */
+		/* Migrate back to system memory and check them. */
+		if (hmm_is_coherent_type(variant->device_number)) {
+			ret = hmm_migrate_dev_to_sys(self->fd, buffer, npages);
+			ASSERT_EQ(ret, 0);
+			ASSERT_EQ(buffer->cpages, npages);
+		}
+
 		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
 			ASSERT_EQ(ptr[i], i);
 
@@ -1354,13 +1428,13 @@ TEST_F(hmm2, snapshot)
 
 	/* Page 5 will be migrated to device 0. */
 	buffer->ptr = p + 5 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_MIGRATE, buffer, 1);
+	ret = hmm_migrate_sys_to_dev(self->fd0, buffer, 1);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, 1);
 
 	/* Page 6 will be migrated to device 1. */
 	buffer->ptr = p + 6 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, 1);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 1);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, 1);
 
@@ -1377,9 +1451,16 @@ TEST_F(hmm2, snapshot)
 	ASSERT_EQ(m[2], HMM_DMIRROR_PROT_ZERO | HMM_DMIRROR_PROT_READ);
 	ASSERT_EQ(m[3], HMM_DMIRROR_PROT_READ);
 	ASSERT_EQ(m[4], HMM_DMIRROR_PROT_WRITE);
-	ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL |
-			HMM_DMIRROR_PROT_WRITE);
-	ASSERT_EQ(m[6], HMM_DMIRROR_PROT_NONE);
+	if (!hmm_is_coherent_type(variant->device_number0)) {
+		ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL |
+				HMM_DMIRROR_PROT_WRITE);
+		ASSERT_EQ(m[6], HMM_DMIRROR_PROT_NONE);
+	} else {
+		ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL |
+				HMM_DMIRROR_PROT_WRITE);
+		ASSERT_EQ(m[6], HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE |
+				HMM_DMIRROR_PROT_WRITE);
+	}
 
 	hmm_buffer_free(buffer);
 }
-- 
2.32.0

[PATCH v4 10/13] tools: update hmm-test to support device coherent type

[Alex Sierra]

Test cases such as migrate_fault and migrate_multiple, were modified to
explicit migrate from device to sys memory without the need of page
faults, when using device coherent type.

Snapshot test case updated to read memory device type first and based
on that, get the proper returned results migrate_ping_pong test case
added to test explicit migration from device to sys memory for both
private and coherent zone types.

Helpers to migrate from device to sys memory and vicerversa
were also added.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 tools/testing/selftests/vm/hmm-tests.c | 123 ++++++++++++++++++++-----
 1 file changed, 102 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 203323967b50..84ec8c4a1dc7 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -44,6 +44,14 @@ struct hmm_buffer {
 	int		fd;
 	uint64_t	cpages;
 	uint64_t	faults;
+	int		zone_device_type;
+};
+
+enum {
+	HMM_PRIVATE_DEVICE_ONE,
+	HMM_PRIVATE_DEVICE_TWO,
+	HMM_COHERENCE_DEVICE_ONE,
+	HMM_COHERENCE_DEVICE_TWO,
 };
 
 #define TWOMEG		(1 << 21)
@@ -60,6 +68,21 @@ FIXTURE(hmm)
 	unsigned int	page_shift;
 };
 
+FIXTURE_VARIANT(hmm)
+{
+	int     device_number;
+};
+
+FIXTURE_VARIANT_ADD(hmm, hmm_device_private)
+{
+	.device_number = HMM_PRIVATE_DEVICE_ONE,
+};
+
+FIXTURE_VARIANT_ADD(hmm, hmm_device_coherent)
+{
+	.device_number = HMM_COHERENCE_DEVICE_ONE,
+};
+
 FIXTURE(hmm2)
 {
 	int		fd0;
@@ -68,6 +91,24 @@ FIXTURE(hmm2)
 	unsigned int	page_shift;
 };
 
+FIXTURE_VARIANT(hmm2)
+{
+	int     device_number0;
+	int     device_number1;
+};
+
+FIXTURE_VARIANT_ADD(hmm2, hmm2_device_private)
+{
+	.device_number0 = HMM_PRIVATE_DEVICE_ONE,
+	.device_number1 = HMM_PRIVATE_DEVICE_TWO,
+};
+
+FIXTURE_VARIANT_ADD(hmm2, hmm2_device_coherent)
+{
+	.device_number0 = HMM_COHERENCE_DEVICE_ONE,
+	.device_number1 = HMM_COHERENCE_DEVICE_TWO,
+};
+
 static int hmm_open(int unit)
 {
 	char pathname[HMM_PATH_MAX];
@@ -81,12 +122,19 @@ static int hmm_open(int unit)
 	return fd;
 }
 
+static bool hmm_is_coherent_type(int dev_num)
+{
+	return (dev_num >= HMM_COHERENCE_DEVICE_ONE);
+}
+
 FIXTURE_SETUP(hmm)
 {
 	self->page_size = sysconf(_SC_PAGE_SIZE);
 	self->page_shift = ffs(self->page_size) - 1;
 
-	self->fd = hmm_open(0);
+	self->fd = hmm_open(variant->device_number);
+	if (self->fd < 0 && hmm_is_coherent_type(variant->device_number))
+		SKIP(exit(0), "DEVICE_COHERENT not available");
 	ASSERT_GE(self->fd, 0);
 }
 
@@ -95,9 +143,11 @@ FIXTURE_SETUP(hmm2)
 	self->page_size = sysconf(_SC_PAGE_SIZE);
 	self->page_shift = ffs(self->page_size) - 1;
 
-	self->fd0 = hmm_open(0);
+	self->fd0 = hmm_open(variant->device_number0);
+	if (self->fd0 < 0 && hmm_is_coherent_type(variant->device_number0))
+		SKIP(exit(0), "DEVICE_COHERENT not available");
 	ASSERT_GE(self->fd0, 0);
-	self->fd1 = hmm_open(1);
+	self->fd1 = hmm_open(variant->device_number1);
 	ASSERT_GE(self->fd1, 0);
 }
 
@@ -144,6 +194,7 @@ static int hmm_dmirror_cmd(int fd,
 	}
 	buffer->cpages = cmd.cpages;
 	buffer->faults = cmd.faults;
+	buffer->zone_device_type = cmd.zone_device_type;
 
 	return 0;
 }
@@ -211,6 +262,20 @@ static void hmm_nanosleep(unsigned int n)
 	nanosleep(&t, NULL);
 }
 
+static int hmm_migrate_sys_to_dev(int fd,
+				   struct hmm_buffer *buffer,
+				   unsigned long npages)
+{
+	return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_DEV, buffer, npages);
+}
+
+static int hmm_migrate_dev_to_sys(int fd,
+				   struct hmm_buffer *buffer,
+				   unsigned long npages)
+{
+	return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_SYS, buffer, npages);
+}
+
 /*
  * Simple NULL test of device open/close.
  */
@@ -875,7 +940,7 @@ TEST_F(hmm, migrate)
 		ptr[i] = i;
 
 	/* Migrate memory to device. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, npages);
 
@@ -923,7 +988,7 @@ TEST_F(hmm, migrate_fault)
 		ptr[i] = i;
 
 	/* Migrate memory to device. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, npages);
 
@@ -936,7 +1001,7 @@ TEST_F(hmm, migrate_fault)
 		ASSERT_EQ(ptr[i], i);
 
 	/* Migrate memory to the device again. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, npages);
 
@@ -976,7 +1041,7 @@ TEST_F(hmm, migrate_shared)
 	ASSERT_NE(buffer->ptr, MAP_FAILED);
 
 	/* Migrate memory to device. */
-	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 	ASSERT_EQ(ret, -ENOENT);
 
 	hmm_buffer_free(buffer);
@@ -1015,7 +1080,7 @@ TEST_F(hmm2, migrate_mixed)
 	p = buffer->ptr;
 
 	/* Migrating a protected area should be an error. */
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, npages);
 	ASSERT_EQ(ret, -EINVAL);
 
 	/* Punch a hole after the first page address. */
@@ -1023,7 +1088,7 @@ TEST_F(hmm2, migrate_mixed)
 	ASSERT_EQ(ret, 0);
 
 	/* We expect an error if the vma doesn't cover the range. */
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, 3);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 3);
 	ASSERT_EQ(ret, -EINVAL);
 
 	/* Page 2 will be a read-only zero page. */
@@ -1055,13 +1120,13 @@ TEST_F(hmm2, migrate_mixed)
 
 	/* Now try to migrate pages 2-5 to device 1. */
 	buffer->ptr = p + 2 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, 4);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 4);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, 4);
 
 	/* Page 5 won't be migrated to device 0 because it's on device 1. */
 	buffer->ptr = p + 5 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_MIGRATE, buffer, 1);
+	ret = hmm_migrate_sys_to_dev(self->fd0, buffer, 1);
 	ASSERT_EQ(ret, -ENOENT);
 	buffer->ptr = p;
 
@@ -1070,8 +1135,12 @@ TEST_F(hmm2, migrate_mixed)
 }
 
 /*
- * Migrate anonymous memory to device private memory and fault it back to system
- * memory multiple times.
+ * Migrate anonymous memory to device memory and back to system memory
+ * multiple times. In case of private zone configuration, this is done
+ * through fault pages accessed by CPU. In case of coherent zone configuration,
+ * the pages from the device should be explicitly migrated back to system memory.
+ * The reason is Coherent device zone has coherent access by CPU, therefore
+ * it will not generate any page fault.
  */
 TEST_F(hmm, migrate_multiple)
 {
@@ -1107,8 +1176,7 @@ TEST_F(hmm, migrate_multiple)
 			ptr[i] = i;
 
 		/* Migrate memory to device. */
-		ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer,
-				      npages);
+		ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
 		ASSERT_EQ(ret, 0);
 		ASSERT_EQ(buffer->cpages, npages);
 
@@ -1116,7 +1184,13 @@ TEST_F(hmm, migrate_multiple)
 		for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
 			ASSERT_EQ(ptr[i], i);
 
-		/* Fault pages back to system memory and check them. */
+		/* Migrate back to system memory and check them. */
+		if (hmm_is_coherent_type(variant->device_number)) {
+			ret = hmm_migrate_dev_to_sys(self->fd, buffer, npages);
+			ASSERT_EQ(ret, 0);
+			ASSERT_EQ(buffer->cpages, npages);
+		}
+
 		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
 			ASSERT_EQ(ptr[i], i);
 
@@ -1354,13 +1428,13 @@ TEST_F(hmm2, snapshot)
 
 	/* Page 5 will be migrated to device 0. */
 	buffer->ptr = p + 5 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_MIGRATE, buffer, 1);
+	ret = hmm_migrate_sys_to_dev(self->fd0, buffer, 1);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, 1);
 
 	/* Page 6 will be migrated to device 1. */
 	buffer->ptr = p + 6 * self->page_size;
-	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_MIGRATE, buffer, 1);
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 1);
 	ASSERT_EQ(ret, 0);
 	ASSERT_EQ(buffer->cpages, 1);
 
@@ -1377,9 +1451,16 @@ TEST_F(hmm2, snapshot)
 	ASSERT_EQ(m[2], HMM_DMIRROR_PROT_ZERO | HMM_DMIRROR_PROT_READ);
 	ASSERT_EQ(m[3], HMM_DMIRROR_PROT_READ);
 	ASSERT_EQ(m[4], HMM_DMIRROR_PROT_WRITE);
-	ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL |
-			HMM_DMIRROR_PROT_WRITE);
-	ASSERT_EQ(m[6], HMM_DMIRROR_PROT_NONE);
+	if (!hmm_is_coherent_type(variant->device_number0)) {
+		ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL |
+				HMM_DMIRROR_PROT_WRITE);
+		ASSERT_EQ(m[6], HMM_DMIRROR_PROT_NONE);
+	} else {
+		ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL |
+				HMM_DMIRROR_PROT_WRITE);
+		ASSERT_EQ(m[6], HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE |
+				HMM_DMIRROR_PROT_WRITE);
+	}
 
 	hmm_buffer_free(buffer);
 }
-- 
2.32.0

[PATCH v4 11/13] tools: update test_hmm script to support SP config

[Alex Sierra]

Add two more parameters to set spm_addr_dev0 & spm_addr_dev1
addresses. These two parameters configure the start SP
addresses for each device in test_hmm driver.
Consequently, this configures zone device type as coherent.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 tools/testing/selftests/vm/test_hmm.sh | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/vm/test_hmm.sh b/tools/testing/selftests/vm/test_hmm.sh
index 0647b525a625..539c9371e592 100755
--- a/tools/testing/selftests/vm/test_hmm.sh
+++ b/tools/testing/selftests/vm/test_hmm.sh
@@ -40,11 +40,26 @@ check_test_requirements()
 
 load_driver()
 {
-	modprobe $DRIVER > /dev/null 2>&1
+	if [ $# -eq 0 ]; then
+		modprobe $DRIVER > /dev/null 2>&1
+	else
+		if [ $# -eq 2 ]; then
+			modprobe $DRIVER spm_addr_dev0=$1 spm_addr_dev1=$2
+				> /dev/null 2>&1
+		else
+			echo "Missing module parameters. Make sure pass"\
+			"spm_addr_dev0 and spm_addr_dev1"
+			usage
+		fi
+	fi
 	if [ $? == 0 ]; then
 		major=$(awk "\$2==\"HMM_DMIRROR\" {print \$1}" /proc/devices)
 		mknod /dev/hmm_dmirror0 c $major 0
 		mknod /dev/hmm_dmirror1 c $major 1
+		if [ $# -eq 2 ]; then
+			mknod /dev/hmm_dmirror2 c $major 2
+			mknod /dev/hmm_dmirror3 c $major 3
+		fi
 	fi
 }
 
@@ -58,7 +73,7 @@ run_smoke()
 {
 	echo "Running smoke test. Note, this test provides basic coverage."
 
-	load_driver
+	load_driver $1 $2
 	$(dirname "${BASH_SOURCE[0]}")/hmm-tests
 	unload_driver
 }
@@ -75,6 +90,9 @@ usage()
 	echo "# Smoke testing"
 	echo "./${TEST_NAME}.sh smoke"
 	echo
+	echo "# Smoke testing with SPM enabled"
+	echo "./${TEST_NAME}.sh smoke <spm_addr_dev0> <spm_addr_dev1>"
+	echo
 	exit 0
 }
 
@@ -84,7 +102,7 @@ function run_test()
 		usage
 	else
 		if [ "$1" = "smoke" ]; then
-			run_smoke
+			run_smoke $2 $3
 		else
 			usage
 		fi
-- 
2.32.0

[PATCH v4 11/13] tools: update test_hmm script to support SP config

[Alex Sierra]

Add two more parameters to set spm_addr_dev0 & spm_addr_dev1
addresses. These two parameters configure the start SP
addresses for each device in test_hmm driver.
Consequently, this configures zone device type as coherent.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 tools/testing/selftests/vm/test_hmm.sh | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/vm/test_hmm.sh b/tools/testing/selftests/vm/test_hmm.sh
index 0647b525a625..539c9371e592 100755
--- a/tools/testing/selftests/vm/test_hmm.sh
+++ b/tools/testing/selftests/vm/test_hmm.sh
@@ -40,11 +40,26 @@ check_test_requirements()
 
 load_driver()
 {
-	modprobe $DRIVER > /dev/null 2>&1
+	if [ $# -eq 0 ]; then
+		modprobe $DRIVER > /dev/null 2>&1
+	else
+		if [ $# -eq 2 ]; then
+			modprobe $DRIVER spm_addr_dev0=$1 spm_addr_dev1=$2
+				> /dev/null 2>&1
+		else
+			echo "Missing module parameters. Make sure pass"\
+			"spm_addr_dev0 and spm_addr_dev1"
+			usage
+		fi
+	fi
 	if [ $? == 0 ]; then
 		major=$(awk "\$2==\"HMM_DMIRROR\" {print \$1}" /proc/devices)
 		mknod /dev/hmm_dmirror0 c $major 0
 		mknod /dev/hmm_dmirror1 c $major 1
+		if [ $# -eq 2 ]; then
+			mknod /dev/hmm_dmirror2 c $major 2
+			mknod /dev/hmm_dmirror3 c $major 3
+		fi
 	fi
 }
 
@@ -58,7 +73,7 @@ run_smoke()
 {
 	echo "Running smoke test. Note, this test provides basic coverage."
 
-	load_driver
+	load_driver $1 $2
 	$(dirname "${BASH_SOURCE[0]}")/hmm-tests
 	unload_driver
 }
@@ -75,6 +90,9 @@ usage()
 	echo "# Smoke testing"
 	echo "./${TEST_NAME}.sh smoke"
 	echo
+	echo "# Smoke testing with SPM enabled"
+	echo "./${TEST_NAME}.sh smoke <spm_addr_dev0> <spm_addr_dev1>"
+	echo
 	exit 0
 }
 
@@ -84,7 +102,7 @@ function run_test()
 		usage
 	else
 		if [ "$1" = "smoke" ]; then
-			run_smoke
+			run_smoke $2 $3
 		else
 			usage
 		fi
-- 
2.32.0

[PATCH v4 12/13] tools: add hmm gup tests for device coherent type

[Alex Sierra]

The intention is to test hmm device coherent type under different get
user pages paths. Also, test gup with FOLL_LONGTERM flag set in
device coherent pages. These pages should get migrated back to system
memory.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
---
 tools/testing/selftests/vm/hmm-tests.c | 105 +++++++++++++++++++++++++
 1 file changed, 105 insertions(+)

diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 84ec8c4a1dc7..61a02a6a3dea 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -36,6 +36,7 @@
  * in the usual include/uapi/... directory.
  */
 #include "../../../../lib/test_hmm_uapi.h"
+#include "../../../../mm/gup_test.h"
 
 struct hmm_buffer {
 	void		*ptr;
@@ -60,6 +61,8 @@ enum {
 #define NTIMES		10
 
 #define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
+/* Just the flags we need, copied from mm.h: */
+#define FOLL_WRITE	0x01	/* check pte is writable */
 
 FIXTURE(hmm)
 {
@@ -1766,4 +1769,106 @@ TEST_F(hmm, exclusive_cow)
 	hmm_buffer_free(buffer);
 }
 
+static int gup_test_exec(int gup_fd, unsigned long addr,
+			 int cmd, int npages, int size)
+{
+	struct gup_test gup = {
+		.nr_pages_per_call	= npages,
+		.addr			= addr,
+		.gup_flags		= FOLL_WRITE,
+		.size			= size,
+	};
+
+	if (ioctl(gup_fd, cmd, &gup)) {
+		perror("ioctl on error\n");
+		return errno;
+	}
+
+	return 0;
+}
+
+/*
+ * Test get user device pages through gup_test. Setting PIN_LONGTERM flag.
+ * This should trigger a migration back to system memory for both, private
+ * and coherent type pages.
+ * This test makes use of gup_test module. Make sure GUP_TEST_CONFIG is added
+ * to your configuration before you run it.
+ */
+TEST_F(hmm, hmm_gup_test)
+{
+	struct hmm_buffer *buffer;
+	int gup_fd;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	unsigned char *m;
+
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	if (gup_fd == -1)
+		SKIP(return, "Skipping test, could not find gup_test driver");
+
+	npages = 3;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr,
+				GUP_BASIC_TEST, 1, self->page_size), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 1 * self->page_size,
+				GUP_FAST_BENCHMARK, 1, self->page_size), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 2 * self->page_size,
+				PIN_LONGTERM_BENCHMARK, 1, self->page_size), 0);
+
+	/* Take snapshot to CPU pagetables */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	m = buffer->mirror;
+	if (hmm_is_coherent_type(variant->device_number)) {
+		ASSERT_EQ(HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL | HMM_DMIRROR_PROT_WRITE, m[0]);
+		ASSERT_EQ(HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL | HMM_DMIRROR_PROT_WRITE, m[1]);
+	} else {
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[0]);
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[1]);
+	}
+	ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[2]);
+	/*
+	 * Check again the content on the pages. Make sure there's no
+	 * corrupted data.
+	 */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	close(gup_fd);
+	hmm_buffer_free(buffer);
+}
 TEST_HARNESS_MAIN
-- 
2.32.0

[PATCH v4 12/13] tools: add hmm gup tests for device coherent type

[Alex Sierra]

The intention is to test hmm device coherent type under different get
user pages paths. Also, test gup with FOLL_LONGTERM flag set in
device coherent pages. These pages should get migrated back to system
memory.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
---
 tools/testing/selftests/vm/hmm-tests.c | 105 +++++++++++++++++++++++++
 1 file changed, 105 insertions(+)

diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 84ec8c4a1dc7..61a02a6a3dea 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -36,6 +36,7 @@
  * in the usual include/uapi/... directory.
  */
 #include "../../../../lib/test_hmm_uapi.h"
+#include "../../../../mm/gup_test.h"
 
 struct hmm_buffer {
 	void		*ptr;
@@ -60,6 +61,8 @@ enum {
 #define NTIMES		10
 
 #define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
+/* Just the flags we need, copied from mm.h: */
+#define FOLL_WRITE	0x01	/* check pte is writable */
 
 FIXTURE(hmm)
 {
@@ -1766,4 +1769,106 @@ TEST_F(hmm, exclusive_cow)
 	hmm_buffer_free(buffer);
 }
 
+static int gup_test_exec(int gup_fd, unsigned long addr,
+			 int cmd, int npages, int size)
+{
+	struct gup_test gup = {
+		.nr_pages_per_call	= npages,
+		.addr			= addr,
+		.gup_flags		= FOLL_WRITE,
+		.size			= size,
+	};
+
+	if (ioctl(gup_fd, cmd, &gup)) {
+		perror("ioctl on error\n");
+		return errno;
+	}
+
+	return 0;
+}
+
+/*
+ * Test get user device pages through gup_test. Setting PIN_LONGTERM flag.
+ * This should trigger a migration back to system memory for both, private
+ * and coherent type pages.
+ * This test makes use of gup_test module. Make sure GUP_TEST_CONFIG is added
+ * to your configuration before you run it.
+ */
+TEST_F(hmm, hmm_gup_test)
+{
+	struct hmm_buffer *buffer;
+	int gup_fd;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	unsigned char *m;
+
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	if (gup_fd == -1)
+		SKIP(return, "Skipping test, could not find gup_test driver");
+
+	npages = 3;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr,
+				GUP_BASIC_TEST, 1, self->page_size), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 1 * self->page_size,
+				GUP_FAST_BENCHMARK, 1, self->page_size), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 2 * self->page_size,
+				PIN_LONGTERM_BENCHMARK, 1, self->page_size), 0);
+
+	/* Take snapshot to CPU pagetables */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	m = buffer->mirror;
+	if (hmm_is_coherent_type(variant->device_number)) {
+		ASSERT_EQ(HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL | HMM_DMIRROR_PROT_WRITE, m[0]);
+		ASSERT_EQ(HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL | HMM_DMIRROR_PROT_WRITE, m[1]);
+	} else {
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[0]);
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[1]);
+	}
+	ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[2]);
+	/*
+	 * Check again the content on the pages. Make sure there's no
+	 * corrupted data.
+	 */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	close(gup_fd);
+	hmm_buffer_free(buffer);
+}
 TEST_HARNESS_MAIN
-- 
2.32.0

[PATCH v4 13/13] tools: add selftests to hmm for COW in device memory

[Alex Sierra]

The objective is to test device migration mechanism in pages marked
as COW, for private and coherent device type. In case of writing to
COW private page(s), a page fault will migrate pages back to system
memory first. Then, these pages will be duplicated. In case of COW
device coherent type, pages are duplicated directly from device
memory.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
---
 tools/testing/selftests/vm/hmm-tests.c | 80 ++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 61a02a6a3dea..76570030ba5b 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -1871,4 +1871,84 @@ TEST_F(hmm, hmm_gup_test)
 	close(gup_fd);
 	hmm_buffer_free(buffer);
 }
+
+/*
+ * Test copy-on-write in device pages.
+ * In case of writing to COW private page(s), a page fault will migrate pages
+ * back to system memory first. Then, these pages will be duplicated. In case
+ * of COW device coherent type, pages are duplicated directly from device
+ * memory.
+ */
+TEST_F(hmm, hmm_cow_in_device)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	unsigned char *m;
+	pid_t pid;
+	int status;
+
+	npages = 4;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	pid = fork();
+	if (pid == -1)
+		ASSERT_EQ(pid, 0);
+	if (!pid) {
+		/* Child process waitd for SIGTERM from the parent. */
+		while (1) {
+		}
+		perror("Should not reach this\n");
+		exit(0);
+	}
+	/* Parent process writes to COW pages(s) and gets a
+	 * new copy in system. In case of device private pages,
+	 * this write causes a migration to system mem first.
+	 */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Terminate child and wait */
+	EXPECT_EQ(0, kill(pid, SIGTERM));
+	EXPECT_EQ(pid, waitpid(pid, &status, 0));
+	EXPECT_NE(0, WIFSIGNALED(status));
+	EXPECT_EQ(SIGTERM, WTERMSIG(status));
+
+	/* Take snapshot to CPU pagetables */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	m = buffer->mirror;
+	for (i = 0; i < npages; i++)
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[i]);
+
+	hmm_buffer_free(buffer);
+}
 TEST_HARNESS_MAIN
-- 
2.32.0

[PATCH v4 13/13] tools: add selftests to hmm for COW in device memory

[Alex Sierra]

The objective is to test device migration mechanism in pages marked
as COW, for private and coherent device type. In case of writing to
COW private page(s), a page fault will migrate pages back to system
memory first. Then, these pages will be duplicated. In case of COW
device coherent type, pages are duplicated directly from device
memory.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
---
 tools/testing/selftests/vm/hmm-tests.c | 80 ++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 61a02a6a3dea..76570030ba5b 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -1871,4 +1871,84 @@ TEST_F(hmm, hmm_gup_test)
 	close(gup_fd);
 	hmm_buffer_free(buffer);
 }
+
+/*
+ * Test copy-on-write in device pages.
+ * In case of writing to COW private page(s), a page fault will migrate pages
+ * back to system memory first. Then, these pages will be duplicated. In case
+ * of COW device coherent type, pages are duplicated directly from device
+ * memory.
+ */
+TEST_F(hmm, hmm_cow_in_device)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	unsigned char *m;
+	pid_t pid;
+	int status;
+
+	npages = 4;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	pid = fork();
+	if (pid == -1)
+		ASSERT_EQ(pid, 0);
+	if (!pid) {
+		/* Child process waitd for SIGTERM from the parent. */
+		while (1) {
+		}
+		perror("Should not reach this\n");
+		exit(0);
+	}
+	/* Parent process writes to COW pages(s) and gets a
+	 * new copy in system. In case of device private pages,
+	 * this write causes a migration to system mem first.
+	 */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Terminate child and wait */
+	EXPECT_EQ(0, kill(pid, SIGTERM));
+	EXPECT_EQ(pid, waitpid(pid, &status, 0));
+	EXPECT_NE(0, WIFSIGNALED(status));
+	EXPECT_EQ(SIGTERM, WTERMSIG(status));
+
+	/* Take snapshot to CPU pagetables */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	m = buffer->mirror;
+	for (i = 0; i < npages; i++)
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[i]);
+
+	hmm_buffer_free(buffer);
+}
 TEST_HARNESS_MAIN
-- 
2.32.0

Re: [PATCH v4 07/13] lib: test_hmm add ioctl to get zone device type

[Andrew Morton]

On Tue, 31 May 2022 10:56:23 -0500 Alex Sierra <alex.sierra@amd.com> wrote:

> new ioctl cmd added to query zone device type. This will be
> used once the test_hmm adds zone device coherent type.
> 
> @@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
>  	return ret;
>  }
>  
> +static int dmirror_get_device_type(struct dmirror *dmirror,
> +			    struct hmm_dmirror_cmd *cmd)
> +{
> +	mutex_lock(&dmirror->mutex);
> +	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
> +	mutex_unlock(&dmirror->mutex);

What does the locking here do?

Presumably cmd->zone_device_type can become out of date the instant the
mutex is released, so what was the point in taking the mutex?

And does it make sense to return potentially out-of-date info to
userspace?  Perhaps this interface simply shouldn't exist?

Re: [PATCH v4 07/13] lib: test_hmm add ioctl to get zone device type

[Andrew Morton]

On Tue, 31 May 2022 10:56:23 -0500 Alex Sierra <alex.sierra@amd.com> wrote:

> new ioctl cmd added to query zone device type. This will be
> used once the test_hmm adds zone device coherent type.
> 
> @@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
>  	return ret;
>  }
>  
> +static int dmirror_get_device_type(struct dmirror *dmirror,
> +			    struct hmm_dmirror_cmd *cmd)
> +{
> +	mutex_lock(&dmirror->mutex);
> +	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
> +	mutex_unlock(&dmirror->mutex);

What does the locking here do?

Presumably cmd->zone_device_type can become out of date the instant the
mutex is released, so what was the point in taking the mutex?

And does it make sense to return potentially out-of-date info to
userspace?  Perhaps this interface simply shouldn't exist?

Re: [PATCH v4 07/13] lib: test_hmm add ioctl to get zone device type

[Sierra Guiza, Alejandro (Alex)]

On 5/31/2022 12:31 PM, Andrew Morton wrote:
> On Tue, 31 May 2022 10:56:23 -0500 Alex Sierra <alex.sierra@amd.com> wrote:
>
>> new ioctl cmd added to query zone device type. This will be
>> used once the test_hmm adds zone device coherent type.
>>
>> @@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
>>   	return ret;
>>   }
>>   
>> +static int dmirror_get_device_type(struct dmirror *dmirror,
>> +			    struct hmm_dmirror_cmd *cmd)
>> +{
>> +	mutex_lock(&dmirror->mutex);
>> +	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
>> +	mutex_unlock(&dmirror->mutex);
> What does the locking here do?
>
> Presumably cmd->zone_device_type can become out of date the instant the
> mutex is released, so what was the point in taking the mutex?

Actually this is not used at all. Thanks for finding it. Honestly, I 
don't remember what we used this type request for.
I will remove all related code  and send a new patch series version.

Regards,
Alex Sierra
>
> And does it make sense to return potentially out-of-date info to
> userspace?  Perhaps this interface simply shouldn't exist?

Re: [PATCH v4 07/13] lib: test_hmm add ioctl to get zone device type

[Sierra Guiza, Alejandro (Alex)]

On 5/31/2022 12:31 PM, Andrew Morton wrote:
> On Tue, 31 May 2022 10:56:23 -0500 Alex Sierra <alex.sierra@amd.com> wrote:
>
>> new ioctl cmd added to query zone device type. This will be
>> used once the test_hmm adds zone device coherent type.
>>
>> @@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror,
>>   	return ret;
>>   }
>>   
>> +static int dmirror_get_device_type(struct dmirror *dmirror,
>> +			    struct hmm_dmirror_cmd *cmd)
>> +{
>> +	mutex_lock(&dmirror->mutex);
>> +	cmd->zone_device_type = dmirror->mdevice->zone_device_type;
>> +	mutex_unlock(&dmirror->mutex);
> What does the locking here do?
>
> Presumably cmd->zone_device_type can become out of date the instant the
> mutex is released, so what was the point in taking the mutex?

Actually this is not used at all. Thanks for finding it. Honestly, I 
don't remember what we used this type request for.
I will remove all related code  and send a new patch series version.

Regards,
Alex Sierra
>
> And does it make sense to return potentially out-of-date info to
> userspace?  Perhaps this interface simply shouldn't exist?