[PATCH v2 08/11] lib: add support for device coherent type in test_hmm
Alex Sierra
alex.sierra at amd.com
Mon Dec 6 18:52:48 UTC 2021
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 at 0x100000000:0x40000,1G at 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 at amd.com>
---
lib/test_hmm.c | 252 +++++++++++++++++++++++++++++++++-----------
lib/test_hmm_uapi.h | 15 ++-
2 files changed, 198 insertions(+), 69 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 9edeff52302e..a1985226d788 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -29,11 +29,22 @@
#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,
@@ -122,6 +133,21 @@ 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);
@@ -572,16 +598,19 @@ 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 alloc 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) {
@@ -601,7 +630,8 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
return dpage;
error:
- __free_page(rpage);
+ if (rpage)
+ __free_page(rpage);
return NULL;
}
@@ -627,12 +657,15 @@ 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);
+ WARN(spage && is_zone_device_page(spage),
+ "page already in device spage pfn: 0x%lx\n",
+ page_to_pfn(spage));
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
@@ -646,6 +679,8 @@ 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)) |
MIGRATE_PFN_LOCKED;
if ((*src & MIGRATE_PFN_WRITE) ||
@@ -724,11 +759,7 @@ 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);
@@ -808,8 +839,106 @@ 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;
+
+ WARN_ON(!is_device_page(spage));
+ 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)) | MIGRATE_PFN_LOCKED;
+ if (*src & MIGRATE_PFN_WRITE)
+ *dst |= MIGRATE_PFN_WRITE;
+ }
+ return 0;
+}
+
+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];
+ 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;
+
+ mmap_read_lock(mm);
+ for (addr = start; addr < end; addr = next) {
+ vma = find_vma(mm, addr);
+ if (!vma || addr < vma->vm_start ||
+ !(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);
+ migrate_vma_finalize(&args);
+ }
+ mmap_read_unlock(mm);
+ mmput(mm);
+
+ return ret;
+
+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;
@@ -853,6 +982,7 @@ 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);
@@ -861,7 +991,7 @@ 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;
@@ -898,12 +1028,22 @@ static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
}
page = hmm_pfn_to_page(entry);
- if (is_device_private_page(page)) {
- /* Is the page migrated to this device or some other? */
- if (dmirror->mdevice == dmirror_page_to_device(page))
+ if (is_device_page(page)) {
+ /* Is page ZONE_DEVICE coherent? */
+ if (!is_device_private_page(page)) {
+ if (dmirror->mdevice == dmirror_page_to_device(page))
+ *perm = HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL;
+ else
+ *perm = HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE;
+ /*
+ * Is page ZONE_DEVICE private migrated to
+ * this device or some other?
+ */
+ } else if (dmirror->mdevice == dmirror_page_to_device(page)) {
*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
- else
+ } else {
*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
+ }
} else if (is_zero_pfn(page_to_pfn(page)))
*perm = HMM_DMIRROR_PROT_ZERO;
else
@@ -1100,8 +1240,12 @@ 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:
@@ -1142,14 +1286,13 @@ 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;
@@ -1157,38 +1300,6 @@ 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)) | MIGRATE_PFN_LOCKED;
- 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;
@@ -1203,7 +1314,7 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
* the mirror but here we use it to hold the page for the simulated
* device memory and that page holds the pointer to the mirror.
*/
- rpage = vmf->page->zone_device_data;
+ rpage = BACKING_PAGE(vmf->page);
dmirror = rpage->zone_device_data;
/* FIXME demonstrate how we can adjust migrate range */
@@ -1213,7 +1324,7 @@ 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;
@@ -1279,14 +1390,26 @@ 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;
+ 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)
goto err_chrdev;
@@ -1308,7 +1431,8 @@ 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
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