[PATCH 5/9] hmm-tests: Add test for unmap and pin
From: Alistair Popple
Date: Mon Feb 08 2021 - 20:11:10 EST
Adds a basic test of the HMM unmap and pin operation.
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
---
lib/test_hmm.c | 107 +++++++++++++++++++++----
lib/test_hmm_uapi.h | 1 +
tools/testing/selftests/vm/hmm-tests.c | 49 +++++++++++
3 files changed, 140 insertions(+), 17 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 98848b96ff09..c78a473250a3 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -46,6 +46,7 @@ struct dmirror_bounce {
unsigned long cpages;
};
+#define DPT_XA_TAG_ATOMIC 1UL
#define DPT_XA_TAG_WRITE 3UL
/*
@@ -83,6 +84,7 @@ struct dmirror_device {
struct cdev cdevice;
struct hmm_devmem *devmem;
+ unsigned int devmem_faults;
unsigned int devmem_capacity;
unsigned int devmem_count;
struct dmirror_chunk **devmem_chunks;
@@ -203,8 +205,18 @@ static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
* Therefore, it is OK to just clear the entry.
*/
xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
- end >> PAGE_SHIFT)
+ end >> PAGE_SHIFT) {
+ /*
+ * Typically this would be done in devmap free page, but as
+ * we're using the XArray to store the reference to the original
+ * page do it here as it doesn't matter if clean up of the
+ * pinned page is delayed.
+ */
+ if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
+ unpin_user_page(xa_untag_pointer(entry));
+
xa_erase(&dmirror->pt, pfn);
+ }
}
static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
@@ -571,7 +583,8 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
}
static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
- struct dmirror *dmirror)
+ struct dmirror *dmirror,
+ int allow_ref)
{
struct dmirror_device *mdevice = dmirror->mdevice;
const unsigned long *src = args->src;
@@ -598,9 +611,17 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
continue;
rpage = dpage->zone_device_data;
- if (spage)
+ if (spage && !(*src & MIGRATE_PFN_PIN))
copy_highpage(rpage, spage);
else
+ /*
+ * In the MIGRATE_PFN_PIN case we don't really
+ * need rpage at all because the existing page is
+ * staying in place and will be mapped. However we need
+ * somewhere to store dmirror and that place is
+ * rpage->zone_device_data so we keep it for
+ * simplicity.
+ */
clear_highpage(rpage);
/*
@@ -620,7 +641,8 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
}
static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
- struct dmirror *dmirror)
+ struct dmirror *dmirror,
+ int allow_ref)
{
unsigned long start = args->start;
unsigned long end = args->end;
@@ -647,8 +669,14 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
* 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;
- if (*dst & MIGRATE_PFN_WRITE)
+ if (*src & MIGRATE_PFN_PIN)
+ entry = migrate_pfn_to_page(*src);
+ else
+ entry = dpage->zone_device_data;
+
+ if (*src & MIGRATE_PFN_PIN)
+ entry = xa_tag_pointer(entry, DPT_XA_TAG_ATOMIC);
+ else if (*dst & MIGRATE_PFN_WRITE)
entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
if (xa_is_err(entry)) {
@@ -662,7 +690,8 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
}
static int dmirror_migrate(struct dmirror *dmirror,
- struct hmm_dmirror_cmd *cmd)
+ struct hmm_dmirror_cmd *cmd,
+ int allow_ref)
{
unsigned long start, end, addr;
unsigned long size = cmd->npages << PAGE_SHIFT;
@@ -673,7 +702,7 @@ static int dmirror_migrate(struct dmirror *dmirror,
struct dmirror_bounce bounce;
struct migrate_vma args;
unsigned long next;
- int ret;
+ int i, ret;
start = cmd->addr;
end = start + size;
@@ -696,8 +725,13 @@ static int dmirror_migrate(struct dmirror *dmirror,
if (next > vma->vm_end)
next = vma->vm_end;
- memset(src_pfns, 0, ARRAY_SIZE(src_pfns));
- memset(dst_pfns, 0, ARRAY_SIZE(dst_pfns));
+ if (allow_ref)
+ for (i = 0; i < 64; ++i)
+ src_pfns[i] = MIGRATE_PFN_PIN;
+ else
+ memset(src_pfns, 0, sizeof(src_pfns));
+ memset(dst_pfns, 0, sizeof(dst_pfns));
+
args.vma = vma;
args.src = src_pfns;
args.dst = dst_pfns;
@@ -709,9 +743,9 @@ static int dmirror_migrate(struct dmirror *dmirror,
if (ret)
goto out;
- dmirror_migrate_alloc_and_copy(&args, dmirror);
+ dmirror_migrate_alloc_and_copy(&args, dmirror, allow_ref);
migrate_vma_pages(&args);
- dmirror_migrate_finalize_and_map(&args, dmirror);
+ dmirror_migrate_finalize_and_map(&args, dmirror, allow_ref);
migrate_vma_finalize(&args);
}
mmap_read_unlock(mm);
@@ -739,6 +773,28 @@ static int dmirror_migrate(struct dmirror *dmirror,
return ret;
}
+static int dmirror_migrate_pin(struct dmirror *dmirror,
+ struct hmm_dmirror_cmd *cmd)
+{
+ void *tmp;
+ int nr_pages = cmd->npages;
+ int ret;
+
+ ret = dmirror_migrate(dmirror, cmd, true);
+
+ tmp = kmalloc(nr_pages << PAGE_SHIFT, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ /* Make sure user access faults */
+ dmirror->mdevice->devmem_faults = 0;
+ if (copy_from_user(tmp, u64_to_user_ptr(cmd->addr), nr_pages << PAGE_SHIFT))
+ ret = -EFAULT;
+ cmd->faults = dmirror->mdevice->devmem_faults;
+
+ return ret;
+}
+
static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
unsigned char *perm, unsigned long entry)
{
@@ -948,7 +1004,11 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
break;
case HMM_DMIRROR_MIGRATE:
- ret = dmirror_migrate(dmirror, &cmd);
+ ret = dmirror_migrate(dmirror, &cmd, false);
+ break;
+
+ case HMM_DMIRROR_MIGRATE_PIN:
+ ret = dmirror_migrate_pin(dmirror, &cmd);
break;
case HMM_DMIRROR_SNAPSHOT:
@@ -1004,20 +1064,31 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
for (addr = start; addr < end; addr += PAGE_SIZE,
src++, dst++) {
struct page *dpage, *spage;
+ void *entry;
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);
+ entry = xa_load(&dmirror->pt, addr >> PAGE_SHIFT);
+ if (entry && xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC) {
+ spage = NULL;
+ dpage = xa_untag_pointer(entry);
+ *dst = migrate_pfn(page_to_pfn(dpage)) |
+ MIGRATE_PFN_LOCKED | MIGRATE_PFN_UNPIN;
+ } else {
+ spage = spage->zone_device_data;
+ dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
+ *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ }
+
if (!dpage)
continue;
lock_page(dpage);
xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
- copy_highpage(dpage, spage);
- *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ if (spage)
+ copy_highpage(dpage, spage);
if (*src & MIGRATE_PFN_WRITE)
*dst |= MIGRATE_PFN_WRITE;
}
@@ -1041,6 +1112,8 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
rpage = vmf->page->zone_device_data;
dmirror = rpage->zone_device_data;
+ dmirror->mdevice->devmem_faults++;
+
/* FIXME demonstrate how we can adjust migrate range */
args.vma = vmf->vma;
args.start = vmf->address;
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 670b4ef2a5b6..b40f4e6affe0 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -33,6 +33,7 @@ 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_MIGRATE_PIN _IOWR('H', 0x04, struct hmm_dmirror_cmd)
/*
* Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 5d1ac691b9f4..7111ebab93c7 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -947,6 +947,55 @@ TEST_F(hmm, migrate_fault)
hmm_buffer_free(buffer);
}
+TEST_F(hmm, migrate_fault_pin)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ int *ptr;
+ int ret;
+
+ npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+ ASSERT_NE(npages, 0);
+ 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_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE_PIN, 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(buffer->faults, npages);
+
+ /* Fault pages back to system memory and check them. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], i);
+
+ hmm_buffer_free(buffer);
+}
+
/*
* Migrate anonymous shared memory to device private memory.
*/
--
2.20.1