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authorAlistair Popple <apopple@nvidia.com>2021-06-30 18:54:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 11:06:03 -0700
commitb659baea75469f0c5bd26f18461dfcdc1bbbac82 (patch)
treee1ab072a9d092d11ad6eb67574ef9b0bf6aba397 /lib
parentb756a3b5e7ead8f6f4b03cea8ac22478ce04c8a8 (diff)
mm: selftests for exclusive device memory
Adds some selftests for exclusive device memory. Link: https://lkml.kernel.org/r/20210616105937.23201-9-apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Acked-by: Jason Gunthorpe <jgg@nvidia.com> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hugh Dickins <hughd@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Peter Xu <peterx@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/test_hmm.c125
-rw-r--r--lib/test_hmm_uapi.h2
2 files changed, 127 insertions, 0 deletions
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index fc7a20bc9b42..8c55c4723692 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -25,6 +25,7 @@
#include <linux/swapops.h>
#include <linux/sched/mm.h>
#include <linux/platform_device.h>
+#include <linux/rmap.h>
#include "test_hmm_uapi.h"
@@ -46,6 +47,7 @@ struct dmirror_bounce {
unsigned long cpages;
};
+#define DPT_XA_TAG_ATOMIC 1UL
#define DPT_XA_TAG_WRITE 3UL
/*
@@ -619,6 +621,54 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
}
}
+static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
+ unsigned long end)
+{
+ unsigned long pfn;
+
+ for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
+ void *entry;
+ struct page *page;
+
+ entry = xa_load(&dmirror->pt, pfn);
+ page = xa_untag_pointer(entry);
+ if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
+ return -EPERM;
+ }
+
+ return 0;
+}
+
+static int dmirror_atomic_map(unsigned long start, unsigned long end,
+ struct page **pages, struct dmirror *dmirror)
+{
+ unsigned long pfn, mapped = 0;
+ int i;
+
+ /* Map the migrated pages into the device's page tables. */
+ mutex_lock(&dmirror->mutex);
+
+ for (i = 0, pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++, i++) {
+ void *entry;
+
+ if (!pages[i])
+ continue;
+
+ entry = pages[i];
+ entry = xa_tag_pointer(entry, DPT_XA_TAG_ATOMIC);
+ entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
+ if (xa_is_err(entry)) {
+ mutex_unlock(&dmirror->mutex);
+ return xa_err(entry);
+ }
+
+ mapped++;
+ }
+
+ mutex_unlock(&dmirror->mutex);
+ return mapped;
+}
+
static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
struct dmirror *dmirror)
{
@@ -661,6 +711,72 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
return 0;
}
+static int dmirror_exclusive(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 page *pages[64];
+ struct dmirror_bounce bounce;
+ 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;
+
+ mmap_read_lock(mm);
+ for (addr = start; addr < end; addr = next) {
+ unsigned long mapped;
+ int i;
+
+ if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
+ next = end;
+ else
+ next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
+
+ ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
+ mapped = dmirror_atomic_map(addr, next, pages, dmirror);
+ for (i = 0; i < ret; i++) {
+ if (pages[i]) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ }
+ }
+
+ if (addr + (mapped << PAGE_SHIFT) < next) {
+ mmap_read_unlock(mm);
+ mmput(mm);
+ return -EBUSY;
+ }
+ }
+ mmap_read_unlock(mm);
+ mmput(mm);
+
+ /* Return the migrated data for verification. */
+ ret = dmirror_bounce_init(&bounce, start, size);
+ if (ret)
+ return ret;
+ mutex_lock(&dmirror->mutex);
+ ret = dmirror_do_read(dmirror, start, end, &bounce);
+ mutex_unlock(&dmirror->mutex);
+ if (ret == 0) {
+ if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
+ bounce.size))
+ ret = -EFAULT;
+ }
+
+ cmd->cpages = bounce.cpages;
+ dmirror_bounce_fini(&bounce);
+ return ret;
+}
+
static int dmirror_migrate(struct dmirror *dmirror,
struct hmm_dmirror_cmd *cmd)
{
@@ -948,6 +1064,15 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp,
ret = dmirror_migrate(dmirror, &cmd);
break;
+ case HMM_DMIRROR_EXCLUSIVE:
+ ret = dmirror_exclusive(dmirror, &cmd);
+ break;
+
+ case HMM_DMIRROR_CHECK_EXCLUSIVE:
+ ret = dmirror_check_atomic(dmirror, cmd.addr,
+ cmd.addr + (cmd.npages << PAGE_SHIFT));
+ break;
+
case HMM_DMIRROR_SNAPSHOT:
ret = dmirror_snapshot(dmirror, &cmd);
break;
diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h
index 670b4ef2a5b6..f14dea5dcd06 100644
--- a/lib/test_hmm_uapi.h
+++ b/lib/test_hmm_uapi.h
@@ -33,6 +33,8 @@ 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)
/*
* Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT.