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// SPDX-License-Identifier: GPL-2.0
/*
* This is a module to test the HMM (Heterogeneous Memory Management)
* mirror and zone device private memory migration APIs of the kernel.
* Userspace programs can register with the driver to mirror their own address
* space and can use the device to read/write any valid virtual address.
*/
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/delay.h>
#include <linux/pagemap.h>
#include <linux/hmm.h>
#include <linux/vmalloc.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/sched/mm.h>
#include <linux/platform_device.h>
#include "test_hmm_uapi.h"
#define DMIRROR_NDEVICES 2
#define DMIRROR_RANGE_FAULT_TIMEOUT 1000
#define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U)
#define DEVMEM_CHUNKS_RESERVE 16
static const struct dev_pagemap_ops dmirror_devmem_ops;
static const struct mmu_interval_notifier_ops dmirror_min_ops;
static dev_t dmirror_dev;
struct dmirror_device;
struct dmirror_bounce {
void *ptr;
unsigned long size;
unsigned long addr;
unsigned long cpages;
};
#define DPT_XA_TAG_WRITE 3UL
/*
* Data structure to track address ranges and register for mmu interval
* notifier updates.
*/
struct dmirror_interval {
struct mmu_interval_notifier notifier;
struct dmirror *dmirror;
};
/*
* Data attached to the open device file.
* Note that it might be shared after a fork().
*/
struct dmirror {
struct dmirror_device *mdevice;
struct xarray pt;
struct mmu_interval_notifier notifier;
struct mutex mutex;
};
/*
* ZONE_DEVICE pages for migration and simulating device memory.
*/
struct dmirror_chunk {
struct dev_pagemap pagemap;
struct dmirror_device *mdevice;
};
/*
* Per device data.
*/
struct dmirror_device {
struct cdev cdevice;
struct hmm_devmem *devmem;
unsigned int devmem_capacity;
unsigned int devmem_count;
struct dmirror_chunk **devmem_chunks;
struct mutex devmem_lock; /* protects the above */
unsigned long calloc;
unsigned long cfree;
struct page *free_pages;
spinlock_t lock; /* protects the above */
};
static struct dmirror_device dmirror_devices[DMIRROR_NDEVICES];
static int dmirror_bounce_init(struct dmirror_bounce *bounce,
unsigned long addr,
unsigned long size)
{
bounce->addr = addr;
bounce->size = size;
bounce->cpages = 0;
bounce->ptr = vmalloc(size);
if (!bounce->ptr)
return -ENOMEM;
return 0;
}
static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
{
vfree(bounce->ptr);
}
static int dmirror_fops_open(struct inode *inode, struct file *filp)
{
struct cdev *cdev = inode->i_cdev;
struct dmirror *dmirror;
int ret;
/* Mirror this process address space */
dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
if (dmirror == NULL)
return -ENOMEM;
dmirror->mdevice = container_of(cdev, struct dmirror_device, cdevice);
mutex_init(&dmirror->mutex);
xa_init(&dmirror->pt);
ret = mmu_interval_notifier_insert(&dmirror->notifier, current->mm,
0, ULONG_MAX & PAGE_MASK, &dmirror_min_ops);
if (ret) {
kfree(dmirror);
return ret;
}
filp->private_data = dmirror;
return 0;
}
static int dmirror_fops_release(struct inode *inode, struct file *filp)
{
struct dmirror *dmirror = filp->private_data;
mmu_interval_notifier_remove(&dmirror->notifier);
xa_destroy(&dmirror->pt);
kfree(dmirror);
return 0;
}
static struct dmirror_device *dmirror_page_to_device(struct page *page)
{
return container_of(page->pgmap, struct dmirror_chunk,
pagemap)->mdevice;
}
static int dmirror_do_fault(struct dmirror *dmirror, struct hmm_range *range)
{
unsigned long *pfns = range->hmm_pfns;
unsigned long pfn;
for (pfn = (range->start >> PAGE_SHIFT);
pfn < (range->end >> PAGE_SHIFT);
pfn++, pfns++) {
struct page *page;
void *entry;
/*
* Since we asked for hmm_range_fault() to populate pages,
* it shouldn't return an error entry on success.
*/
WARN_ON(*pfns & HMM_PFN_ERROR);
WARN_ON(!(*pfns & HMM_PFN_VALID));
page = hmm_pfn_to_page(*pfns);
WARN_ON(!page);
entry = page;
if (*pfns & HMM_PFN_WRITE)
entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
else if (WARN_ON(range->default_flags & HMM_PFN_WRITE))
return -EFAULT;
entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
if (xa_is_err(entry))
return xa_err(entry);
}
return 0;
}
static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
unsigned long end)
{
unsigned long pfn;
void *entry;
/*
* The XArray doesn't hold references to pages since it relies on
* the mmu notifier to clear page pointers when they become stale.
* Therefore, it is OK to just clear the entry.
*/
xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
end >> PAGE_SHIFT)
xa_erase(&dmirror->pt, pfn);
}
static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
const struct mmu_notifier_range *range,
unsigned long cur_seq)
{
struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
/*
* Ignore invalidation callbacks for device private pages since
* the invalidation is handled as part of the migration process.
*/
if (range->event == MMU_NOTIFY_MIGRATE &&
range->migrate_pgmap_owner == dmirror->mdevice)
return true;
if (mmu_notifier_range_blockable(range))
mutex_lock(&dmirror->mutex);
else if (!mutex_trylock(&dmirror->mutex))
return false;
mmu_interval_set_seq(mni, cur_seq);
dmirror_do_update(dmirror, range->start, range->end);
mutex_unlock(&dmirror->mutex);
return true;
}
static const struct mmu_interval_notifier_ops dmirror_min_ops = {
.invalidate = dmirror_interval_invalidate,
};
static int dmirror_range_fault(struct dmirror *dmirror,
struct hmm_range *range)
{
struct mm_struct *mm = dmirror->notifier.mm;
unsigned long timeout =
jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
int ret;
while (true) {
if (time_after(jiffies, timeout)) {
ret = -EBUSY;
goto out;
}
range->notifier_seq = mmu_interval_read_begin(range->notifier);
mmap_read_lock(mm);
ret = hmm_range_fault(range);
mmap_read_unlock(mm);
if (ret) {
if (ret == -EBUSY)
continue;
goto out;
}
mutex_lock(&dmirror->mutex);
if (mmu_interval_read_retry(range->notifier,
range->notifier_seq)) {
mutex_unlock(&dmirror->mutex);
continue;
}
break;
}
ret = dmirror_do_fault(dmirror, range);
mutex_unlock(&dmirror->mutex);
out:
return ret;
}
static int dmirror_fault(struct dmirror *dmirror, unsigned long start,
unsigned long end, bool write)
{
struct mm_struct *mm = dmirror->notifier.mm;
unsigned long addr;
unsigned long pfns[64];
struct hmm_range range = {
.notifier = &dmirror->notifier,
.hmm_pfns = pfns,
.pfn_flags_mask = 0,
.default_flags =
HMM_PFN_REQ_FAULT | (write ? HMM_PFN_REQ_WRITE : 0),
.dev_private_owner = dmirror->mdevice,
};
int ret = 0;
/* Since the mm is for the mirrored process, get a reference first. */
if (!mmget_not_zero(mm))
return 0;
for (addr = start; addr < end; addr = range.end) {
range.start = addr;
range.end = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
ret = dmirror_range_fault(dmirror, &range);
if (ret)
break;
}
mmput(mm);
return ret;
}
static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
unsigned long end, struct dmirror_bounce *bounce)
{
unsigned long pfn;
void *ptr;
ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
void *entry;
struct page *page;
void *tmp;
entry = xa_load(&dmirror->pt, pfn);
page = xa_untag_pointer(entry);
if (!page)
return -ENOENT;
tmp = kmap(page);
memcpy(ptr, tmp, PAGE_SIZE);
kunmap(page);
ptr += PAGE_SIZE;
bounce->cpages++;
}
return 0;
}
static int dmirror_read(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
{
struct dmirror_bounce bounce;
unsigned long start, end;
unsigned long size = cmd->npages << PAGE_SHIFT;
int ret;
start = cmd->addr;
end = start + size;
if (end < start)
return -EINVAL;
ret = dmirror_bounce_init(&bounce, start, size);
if (ret)
return ret;
while (1) {
mutex_lock(&dmirror->mutex);
ret = dmirror_do_read(dmirror, start, end, &bounce);
mutex_unlock(&dmirror->mutex);
if (ret != -ENOENT)
break;
start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
ret = dmirror_fault(dmirror, start, end, false);
if (ret)
break;
cmd->faults++;
}
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_do_write(struct dmirror *dmirror, unsigned long start,
unsigned long end, struct dmirror_bounce *bounce)
{
unsigned long pfn;
void *ptr;
ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
void *entry;
struct page *page;
void *tmp;
entry = xa_load(&dmirror->pt, pfn);
page = xa_untag_pointer(entry);
if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
return -ENOENT;
tmp = kmap(page);
memcpy(tmp, ptr, PAGE_SIZE);
kunmap(page);
ptr += PAGE_SIZE;
bounce->cpages++;
}
return 0;
}
static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
{
struct dmirror_bounce bounce;
unsigned long start, end;
unsigned long size = cmd->npages << PAGE_SHIFT;
int ret;
start = cmd->addr;
end = start + size;
if (end < start)
return -EINVAL;
ret = dmirror_bounce_init(&bounce, start, size);
if (ret)
return ret;
if (copy_from_user(bounce.ptr, u64_to_user_ptr(cmd->ptr),
bounce.size)) {
ret = -EFAULT;
goto fini;
}
while (1) {
mutex_lock(&dmirror->mutex);
ret = dmirror_do_write(dmirror, start, end, &bounce);
mutex_unlock(&dmirror->mutex);
if (ret != -ENOENT)
break;
start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
ret = dmirror_fault(dmirror, start, end, true);
if (ret)
break;
cmd->faults++;
}
fini:
cmd->cpages = bounce.cpages;
dmirror_bounce_fini(&bounce);
return ret;
}
static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
struct page **ppage)
{
struct dmirror_chunk *devmem;
struct resource *res;
unsigned long pfn;
unsigned long pfn_first;
unsigned long pfn_last;
void *ptr;
devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
if (!devmem)
return false;
res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
"hmm_dmirror");
if (IS_ERR(res))
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;
mutex_lock(&mdevice->devmem_lock);
if (mdevice->devmem_count == mdevice->devmem_capacity) {
struct dmirror_chunk **new_chunks;
unsigned int new_capacity;
new_capacity = mdevice->devmem_capacity +
DEVMEM_CHUNKS_RESERVE;
new_chunks = krealloc(mdevice->devmem_chunks,
sizeof(new_chunks[0]) * new_capacity,
GFP_KERNEL);
if (!new_chunks)
goto err_release;
mdevice->devmem_capacity = new_capacity;
mdevice->devmem_chunks = new_chunks;
}
ptr = memremap_pages(&devmem->pagemap, numa_node_id());
if (IS_ERR(ptr))
goto err_release;
devmem->mdevice = mdevice;
pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
pfn_last = pfn_first + (range_len(&devmem->pagemap.range) >> PAGE_SHIFT);
mdevice->devmem_chunks[mdevice->devmem_count++] = devmem;
mutex_unlock(&mdevice->devmem_lock);
pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n",
DEVMEM_CHUNK_SIZE / (1024 * 1024),
mdevice->devmem_count,
mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),
pfn_first, pfn_last);
spin_lock(&mdevice->lock);
for (pfn = pfn_first; pfn < pfn_last; pfn++) {
struct page *page = pfn_to_page(pfn);
page->zone_device_data = mdevice->free_pages;
mdevice->free_pages = page;
}
if (ppage) {
*ppage = mdevice->free_pages;
mdevice->free_pages = (*ppage)->zone_device_data;
mdevice->calloc++;
}
spin_unlock(&mdevice->lock);
return true;
err_release:
mutex_unlock(&mdevice->devmem_lock);
release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
err_devmem:
kfree(devmem);
return false;
}
static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
{
struct page *dpage = NULL;
struct page *rpage;
/*
* This is a fake device so we alloc real system memory to store
* our device memory.
*/
rpage = alloc_page(GFP_HIGHUSER);
if (!rpage)
return NULL;
spin_lock(&mdevice->lock);
if (mdevice->free_pages) {
dpage = mdevice->free_pages;
mdevice->free_pages = dpage->zone_device_data;
mdevice->calloc++;
spin_unlock(&mdevice->lock);
} else {
spin_unlock(&mdevice->lock);
if (!dmirror_allocate_chunk(mdevice, &dpage))
goto error;
}
dpage->zone_device_data = rpage;
get_page(dpage);
lock_page(dpage);
return dpage;
error:
__free_page(rpage);
return NULL;
}
static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
struct dmirror *dmirror)
{
struct dmirror_device *mdevice = dmirror->mdevice;
const unsigned long *src = args->src;
unsigned long *dst = args->dst;
unsigned long addr;
for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
src++, dst++) {
struct page *spage;
struct page *dpage;
struct page *rpage;
if (!(*src & MIGRATE_PFN_MIGRATE))
continue;
/*
* Note that spage might be NULL which is OK since it is an
* unallocated pte_none() or read-only zero page.
*/
spage = migrate_pfn_to_page(*src);
dpage = dmirror_devmem_alloc_page(mdevice);
if (!dpage)
continue;
rpage = dpage->zone_device_data;
if (spage)
copy_highpage(rpage, spage);
else
clear_highpage(rpage);
/*
* Normally, a device would use the page->zone_device_data to
* point to 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->zone_device_data = dmirror;
*dst = migrate_pfn(page_to_pfn(dpage)) |
MIGRATE_PFN_LOCKED;
if ((*src & MIGRATE_PFN_WRITE) ||
(!spage && args->vma->vm_flags & VM_WRITE))
*dst |= MIGRATE_PFN_WRITE;
}
}
static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
struct dmirror *dmirror)
{
unsigned long start = args->start;
unsigned long end = args->end;
const unsigned long *src = args->src;
const unsigned long *dst = args->dst;
unsigned long pfn;
/* Map the migrated pages into the device's page tables. */
mutex_lock(&dmirror->mutex);
for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
src++, dst++) {
struct page *dpage;
void *entry;
if (!(*src & MIGRATE_PFN_MIGRATE))
continue;
dpage = migrate_pfn_to_page(*dst);
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;
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)) {
mutex_unlock(&dmirror->mutex);
return xa_err(entry);
}
}
mutex_unlock(&dmirror->mutex);
return 0;
}
static int dmirror_migrate(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 dmirror_bounce bounce;
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 = MIGRATE_VMA_SELECT_SYSTEM;
ret = migrate_vma_setup(&args);
if (ret)
goto out;
dmirror_migrate_alloc_and_copy(&args, dmirror);
migrate_vma_pages(&args);
dmirror_migrate_finalize_and_map(&args, dmirror);
migrate_vma_finalize(&args);
}
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;
out:
mmap_read_unlock(mm);
mmput(mm);
return ret;
}
static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
unsigned char *perm, unsigned long entry)
{
struct page *page;
if (entry & HMM_PFN_ERROR) {
*perm = HMM_DMIRROR_PROT_ERROR;
return;
}
if (!(entry & HMM_PFN_VALID)) {
*perm = HMM_DMIRROR_PROT_NONE;
return;
}
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))
*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
else
*perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
} else if (is_zero_pfn(page_to_pfn(page)))
*perm = HMM_DMIRROR_PROT_ZERO;
else
*perm = HMM_DMIRROR_PROT_NONE;
if (entry & HMM_PFN_WRITE)
*perm |= HMM_DMIRROR_PROT_WRITE;
else
*perm |= HMM_DMIRROR_PROT_READ;
if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
*perm |= HMM_DMIRROR_PROT_PMD;
else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
*perm |= HMM_DMIRROR_PROT_PUD;
}
static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
const struct mmu_notifier_range *range,
unsigned long cur_seq)
{
struct dmirror_interval *dmi =
container_of(mni, struct dmirror_interval, notifier);
struct dmirror *dmirror = dmi->dmirror;
if (mmu_notifier_range_blockable(range))
mutex_lock(&dmirror->mutex);
else if (!mutex_trylock(&dmirror->mutex))
return false;
/*
* Snapshots only need to set the sequence number since any
* invalidation in the interval invalidates the whole snapshot.
*/
mmu_interval_set_seq(mni, cur_seq);
mutex_unlock(&dmirror->mutex);
return true;
}
static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
.invalidate = dmirror_snapshot_invalidate,
};
static int dmirror_range_snapshot(struct dmirror *dmirror,
struct hmm_range *range,
unsigned char *perm)
{
struct mm_struct *mm = dmirror->notifier.mm;
struct dmirror_interval notifier;
unsigned long timeout =
jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
unsigned long i;
unsigned long n;
int ret = 0;
notifier.dmirror = dmirror;
range->notifier = &notifier.notifier;
ret = mmu_interval_notifier_insert(range->notifier, mm,
range->start, range->end - range->start,
&dmirror_mrn_ops);
if (ret)
return ret;
while (true) {
if (time_after(jiffies, timeout)) {
ret = -EBUSY;
goto out;
}
range->notifier_seq = mmu_interval_read_begin(range->notifier);
mmap_read_lock(mm);
ret = hmm_range_fault(range);
mmap_read_unlock(mm);
if (ret) {
if (ret == -EBUSY)
continue;
goto out;
}
mutex_lock(&dmirror->mutex);
if (mmu_interval_read_retry(range->notifier,
range->notifier_seq)) {
mutex_unlock(&dmirror->mutex);
continue;
}
break;
}
n = (range->end - range->start) >> PAGE_SHIFT;
for (i = 0; i < n; i++)
dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
mutex_unlock(&dmirror->mutex);
out:
mmu_interval_notifier_remove(range->notifier);
return ret;
}
static int dmirror_snapshot(struct dmirror *dmirror,
struct hmm_dmirror_cmd *cmd)
{
struct mm_struct *mm = dmirror->notifier.mm;
unsigned long start, end;
unsigned long size = cmd->npages << PAGE_SHIFT;
unsigned long addr;
unsigned long next;
unsigned long pfns[64];
unsigned char perm[64];
char __user *uptr;
struct hmm_range range = {
.hmm_pfns = pfns,
.dev_private_owner = dmirror->mdevice,
};
int ret = 0;
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;
/*
* Register a temporary notifier to detect invalidations even if it
* overlaps with other mmu_interval_notifiers.
*/
uptr = u64_to_user_ptr(cmd->ptr);
for (addr = start; addr < end; addr = next) {
unsigned long n;
next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
range.start = addr;
range.end = next;
ret = dmirror_range_snapshot(dmirror, &range, perm);
if (ret)
break;
n = (range.end - range.start) >> PAGE_SHIFT;
if (copy_to_user(uptr, perm, n)) {
ret = -EFAULT;
break;
}
cmd->cpages += n;
uptr += n;
}
mmput(mm);
return ret;
}
static long dmirror_fops_unlocked_ioctl(struct file *filp,
unsigned int command,
unsigned long arg)
{
void __user *uarg = (void __user *)arg;
struct hmm_dmirror_cmd cmd;
struct dmirror *dmirror;
int ret;
dmirror = filp->private_data;
if (!dmirror)
return -EINVAL;
if (copy_from_user(&cmd, uarg, sizeof(cmd)))
return -EFAULT;
if (cmd.addr & ~PAGE_MASK)
return -EINVAL;
if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
return -EINVAL;
cmd.cpages = 0;
cmd.faults = 0;
switch (command) {
case HMM_DMIRROR_READ:
ret = dmirror_read(dmirror, &cmd);
break;
case HMM_DMIRROR_WRITE:
ret = dmirror_write(dmirror, &cmd);
break;
case HMM_DMIRROR_MIGRATE:
ret = dmirror_migrate(dmirror, &cmd);
break;
case HMM_DMIRROR_SNAPSHOT:
ret = dmirror_snapshot(dmirror, &cmd);
break;
default:
return -EINVAL;
}
if (ret)
return ret;
if (copy_to_user(uarg, &cmd, sizeof(cmd)))
return -EFAULT;
return 0;
}
static const struct file_operations dmirror_fops = {
.open = dmirror_fops_open,
.release = dmirror_fops_release,
.unlocked_ioctl = dmirror_fops_unlocked_ioctl,
.llseek = default_llseek,
.owner = THIS_MODULE,
};
static void dmirror_devmem_free(struct page *page)
{
struct page *rpage = page->zone_device_data;
struct dmirror_device *mdevice;
if (rpage)
__free_page(rpage);
mdevice = dmirror_page_to_device(page);
spin_lock(&mdevice->lock);
mdevice->cfree++;
page->zone_device_data = mdevice->free_pages;
mdevice->free_pages = 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;
unsigned long src_pfns;
unsigned long dst_pfns;
struct page *rpage;
struct dmirror *dmirror;
vm_fault_t ret;
/*
* Normally, a device would use the page->zone_device_data to point to
* 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;
dmirror = rpage->zone_device_data;
/* FIXME demonstrate how we can adjust migrate range */
args.vma = vmf->vma;
args.start = vmf->address;
args.end = args.start + PAGE_SIZE;
args.src = &src_pfns;
args.dst = &dst_pfns;
args.pgmap_owner = dmirror->mdevice;
args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
if (migrate_vma_setup(&args))
return VM_FAULT_SIGBUS;
ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
if (ret)
return ret;
migrate_vma_pages(&args);
/*
* No device finalize step is needed since
* dmirror_devmem_fault_alloc_and_copy() will have already
* invalidated the device page table.
*/
migrate_vma_finalize(&args);
return 0;
}
static const struct dev_pagemap_ops dmirror_devmem_ops = {
.page_free = dmirror_devmem_free,
.migrate_to_ram = dmirror_devmem_fault,
};
static int dmirror_device_init(struct dmirror_device *mdevice, int id)
{
dev_t dev;
int ret;
dev = MKDEV(MAJOR(dmirror_dev), id);
mutex_init(&mdevice->devmem_lock);
spin_lock_init(&mdevice->lock);
cdev_init(&mdevice->cdevice, &dmirror_fops);
mdevice->cdevice.owner = THIS_MODULE;
ret = cdev_add(&mdevice->cdevice, dev, 1);
if (ret)
return ret;
/* Build a list of free ZONE_DEVICE private struct pages */
dmirror_allocate_chunk(mdevice, NULL);
return 0;
}
static void dmirror_device_remove(struct dmirror_device *mdevice)
{
unsigned int i;
if (mdevice->devmem_chunks) {
for (i = 0; i < mdevice->devmem_count; i++) {
struct dmirror_chunk *devmem =
mdevice->devmem_chunks[i];
memunmap_pages(&devmem->pagemap);
release_mem_region(devmem->pagemap.range.start,
range_len(&devmem->pagemap.range));
kfree(devmem);
}
kfree(mdevice->devmem_chunks);
}
cdev_del(&mdevice->cdevice);
}
static int __init hmm_dmirror_init(void)
{
int ret;
int id;
ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
"HMM_DMIRROR");
if (ret)
goto err_unreg;
for (id = 0; id < DMIRROR_NDEVICES; id++) {
ret = dmirror_device_init(dmirror_devices + id, id);
if (ret)
goto err_chrdev;
}
pr_info("HMM test module loaded. This is only for testing HMM.\n");
return 0;
err_chrdev:
while (--id >= 0)
dmirror_device_remove(dmirror_devices + id);
unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
err_unreg:
return ret;
}
static void __exit hmm_dmirror_exit(void)
{
int id;
for (id = 0; id < DMIRROR_NDEVICES; id++)
dmirror_device_remove(dmirror_devices + id);
unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
}
module_init(hmm_dmirror_init);
module_exit(hmm_dmirror_exit);
MODULE_LICENSE("GPL");