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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 6/6] xen-gntdev: Introduce HVM version of gntdev
On 12/14/2010 06:55 AM, Daniel De Graaf wrote:
> HVM does not allow direct PTE modification, so guest pages must be
> allocated and used for grant mappings. If Xen does not provide an
> auto-translated physmap, the existing direct PTE modification is more
> efficient.
I haven't looked at this in detail, but doing a complete duplication of
the driver doesn't seem like a great idea.
Also, Stefano and I have been working on a modification to gntdev to
make sure that each granted page is backed with a proper struct page (so
that direct aio works on them). Would this help the hvm case?
Thanks,
J
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
> ---
> drivers/xen/Makefile | 2 +
> drivers/xen/gntdev-hvm.c | 601
> ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/xen/gntdev.c | 3 +
> 3 files changed, 606 insertions(+), 0 deletions(-)
> create mode 100644 drivers/xen/gntdev-hvm.c
>
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index 9814c1d..ab0e6eb 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
> obj-$(CONFIG_XEN_BALLOON) += balloon.o
> obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o
> obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev.o
> +obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev-hvm.o
> obj-$(CONFIG_XEN_GRANT_DEV_ALLOC) += xen-gntalloc.o
> obj-$(CONFIG_XEN_PCIDEV_BACKEND) += pciback/
> obj-$(CONFIG_XEN_BLKDEV_BACKEND) += blkback/
> @@ -26,4 +27,5 @@ obj-$(CONFIG_XEN_PLATFORM_PCI) += platform-pci.o
>
> xen-evtchn-y := evtchn.o
> xen-gntdev-y := gntdev.o
> +xen-gntdev-hvm-y := gntdev-hvm.o
> xen-gntalloc-y := gntalloc.o
> diff --git a/drivers/xen/gntdev-hvm.c b/drivers/xen/gntdev-hvm.c
> new file mode 100644
> index 0000000..331d5af
> --- /dev/null
> +++ b/drivers/xen/gntdev-hvm.c
> @@ -0,0 +1,601 @@
> +/******************************************************************************
> + * gntdev.c
> + *
> + * Device for accessing (in user-space) pages that have been granted by other
> + * domains.
> + *
> + * Copyright (c) 2006-2007, D G Murray.
> + * (c) 2009 Gerd Hoffmann <kraxel@xxxxxxxxxx>
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/miscdevice.h>
> +#include <linux/fs.h>
> +#include <linux/mm.h>
> +#include <linux/mman.h>
> +#include <linux/types.h>
> +#include <linux/uaccess.h>
> +#include <linux/sched.h>
> +#include <linux/spinlock.h>
> +#include <linux/vmalloc.h>
> +
> +#include <xen/xen.h>
> +#include <xen/grant_table.h>
> +#include <xen/gntdev.h>
> +#include <xen/interface/memory.h>
> +#include <asm/xen/hypervisor.h>
> +#include <asm/xen/hypercall.h>
> +#include <asm/xen/page.h>
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Derek G. Murray <Derek.Murray@xxxxxxxxxxxx>, "
> + "Gerd Hoffmann <kraxel@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("User-space granted page access driver");
> +
> +static int debug = 0;
> +module_param(debug, int, 0644);
> +static int limit = 1024*1024;
> +module_param(limit, int, 0644);
> +static atomic_t pages_mapped = ATOMIC_INIT(0);
> +
> +struct gntdev_priv {
> + struct list_head maps;
> + spinlock_t lock;
> +};
> +
> +struct granted_page {
> + struct page* page;
> + union {
> + struct ioctl_gntdev_grant_ref target;
> + grant_handle_t handle;
> + };
> +};
> +
> +struct grant_map {
> + struct list_head next;
> + int index;
> + int count;
> + atomic_t users;
> + int is_mapped:1;
> + int is_ro:1;
> + struct granted_page pages[0];
> +};
> +
> +static struct vm_operations_struct gntdev_vmops;
> +
> +/* ------------------------------------------------------------------ */
> +
> +static void gntdev_print_maps(struct gntdev_priv *priv,
> + char *text, int text_index)
> +{
> + struct grant_map *map;
> +
> + printk("%s: maps list (priv %p)\n", __FUNCTION__, priv);
> + list_for_each_entry(map, &priv->maps, next) {
> + printk(" %p: %2d+%2d, r%c, %s %d,%d %s\n", map,
> + map->index, map->count, map->is_ro ? 'o' : 'w',
> + map->is_mapped ? "use,hnd" : "dom,ref",
> + map->is_mapped ? atomic_read(&map->users)
> + : map->pages[0].target.domid,
> + map->is_mapped ? map->pages[0].handle
> + : map->pages[0].target.ref,
> + map->index == text_index && text ? text : "");
> + }
> +}
> +
> +static struct grant_map *gntdev_alloc_map(int count,
> + struct ioctl_gntdev_grant_ref* grants)
> +{
> + struct grant_map *add;
> + int i;
> +
> + add = kzalloc(sizeof(*add) + sizeof(add->pages[0])*count, GFP_KERNEL);
> + if (!add)
> + return NULL;
> +
> + atomic_set(&add->users, 1);
> + add->count = count;
> +
> + for(i = 0; i < count; i++)
> + add->pages[i].target = grants[i];
> +
> + return add;
> +}
> +
> +static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
> +{
> + struct grant_map *map;
> +
> + spin_lock(&priv->lock);
> +
> + list_for_each_entry(map, &priv->maps, next) {
> + if (add->index + add->count < map->index) {
> + list_add_tail(&add->next, &map->next);
> + goto done;
> + }
> + add->index = map->index + map->count;
> + }
> + list_add_tail(&add->next, &priv->maps);
> +
> +done:
> + if (debug)
> + gntdev_print_maps(priv, "[new]", add->index);
> +
> + spin_unlock(&priv->lock);
> +}
> +
> +static void __gntdev_del_map(struct gntdev_priv *priv, struct grant_map *map)
> +{
> + list_del(&map->next);
> +}
> +
> +static void gntdev_del_map(struct gntdev_priv *priv, struct grant_map *map)
> +{
> + spin_lock(&priv->lock);
> + __gntdev_del_map(priv, map);
> + spin_unlock(&priv->lock);
> +}
> +
> +static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv, int
> index,
> + int count)
> +{
> + struct grant_map *map;
> +
> + list_for_each_entry(map, &priv->maps, next) {
> + if (map->index != index)
> + continue;
> + if (map->count != count)
> + continue;
> + return map;
> + }
> + return NULL;
> +}
> +
> +static void gntdev_unmap_fast(struct grant_map *map,
> + struct gnttab_unmap_grant_ref *unmap_ops)
> +{
> + int err, flags, i, unmap_size = 0;
> + unsigned long pfn;
> + phys_addr_t mfn;
> +
> + flags = GNTMAP_host_map;
> + if (map->is_ro)
> + flags |= GNTMAP_readonly;
> +
> + for (i=0; i < map->count; i++) {
> + if (!map->pages[i].page)
> + continue;
> + pfn = page_to_pfn(map->pages[i].page);
> + mfn = (phys_addr_t)pfn_to_kaddr(pfn);
> + gnttab_set_unmap_op(&unmap_ops[unmap_size], mfn, flags,
> + map->pages[i].handle);
> + unmap_size++;
> + }
> +
> + err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
> + unmap_ops, unmap_size);
> + WARN_ON(err);
> +
> + for (i = 0; i < unmap_size; i++)
> + WARN_ON(unmap_ops[i].status);
> +}
> +
> +// for the out-of-memory case
> +static void gntdev_unmap_slow(struct grant_map *map)
> +{
> + int err, flags, i;
> + unsigned long pfn;
> + phys_addr_t mfn;
> + struct gnttab_unmap_grant_ref unmap_op;
> +
> + flags = GNTMAP_host_map;
> + if (map->is_ro)
> + flags |= GNTMAP_readonly;
> +
> + for (i=0; i < map->count; i++) {
> + if (!map->pages[i].page)
> + continue;
> +
> + pfn = page_to_pfn(map->pages[i].page);
> + mfn = (phys_addr_t)pfn_to_kaddr(pfn);
> + gnttab_set_unmap_op(&unmap_op, mfn, flags,
> map->pages[i].handle);
> + err = HYPERVISOR_grant_table_op(
> + GNTTABOP_unmap_grant_ref, &unmap_op, 1);
> + WARN_ON(err);
> + WARN_ON(unmap_op.status);
> + }
> +}
> +
> +static void gntdev_put_map(struct grant_map *map)
> +{
> + struct gnttab_unmap_grant_ref *unmap_ops;
> + int i;
> + if (!map)
> + return;
> + if (!atomic_dec_and_test(&map->users))
> + return;
> + if (debug)
> + printk("%s: unmap %p (%d pages)\n", __FUNCTION__, map,
> map->count);
> + if (map->is_mapped) {
> + unmap_ops = kzalloc(sizeof(unmap_ops[0]) * map->count,
> + GFP_TEMPORARY);
> + if (likely(unmap_ops)) {
> + gntdev_unmap_fast(map, unmap_ops);
> + kfree(unmap_ops);
> + } else {
> + gntdev_unmap_slow(map);
> + }
> +
> + atomic_sub(map->count, &pages_mapped);
> + }
> + for (i=0; i < map->count; i++)
> + if (map->pages[i].page)
> + __free_page(map->pages[i].page);
> + kfree(map);
> +}
> +
> +static int gntdev_open(struct inode *inode, struct file *flip)
> +{
> + struct gntdev_priv *priv;
> +
> + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + INIT_LIST_HEAD(&priv->maps);
> + spin_lock_init(&priv->lock);
> +
> + flip->private_data = priv;
> + if (debug)
> + printk("%s: priv %p\n", __FUNCTION__, priv);
> +
> + return 0;
> +}
> +
> +static int gntdev_release(struct inode *inode, struct file *flip)
> +{
> + struct gntdev_priv *priv = flip->private_data;
> + struct grant_map *map;
> +
> + if (debug) {
> + printk("%s: priv %p\n", __FUNCTION__, priv);
> + gntdev_print_maps(priv, NULL, 0);
> + }
> +
> + spin_lock(&priv->lock);
> + while (!list_empty(&priv->maps)) {
> + map = list_entry(priv->maps.next, struct grant_map, next);
> + list_del(&map->next);
> + gntdev_put_map(map);
> + }
> + spin_unlock(&priv->lock);
> +
> + kfree(priv);
> + return 0;
> +}
> +
> +static int gntdev_do_map(struct grant_map *map)
> +{
> + int err, flags, i;
> + struct page* page;
> + phys_addr_t mfn;
> + struct gnttab_map_grant_ref* map_ops;
> +
> + flags = GNTMAP_host_map;
> + if (map->is_ro)
> + flags |= GNTMAP_readonly;
> +
> + err = -ENOMEM;
> +
> + if (unlikely(atomic_add_return(map->count, &pages_mapped) > limit)) {
> + if (debug)
> + printk("%s: maps full\n", __FUNCTION__);
> + goto out;
> + }
> +
> + map_ops = kzalloc(sizeof(map_ops[0]) * map->count, GFP_TEMPORARY);
> + if (!map_ops)
> + goto out;
> +
> + for (i = 0; i < map->count; i++) {
> + page = alloc_page(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO);
> + if (unlikely(!page))
> + goto out_free;
> + map->pages[i].page = page;
> + mfn = (phys_addr_t)pfn_to_kaddr(page_to_pfn(page));
> + gnttab_set_map_op(&map_ops[i], mfn, flags,
> + map->pages[i].target.ref,
> + map->pages[i].target.domid);
> + }
> + err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
> + map_ops, map->count);
> + if (WARN_ON(err))
> + goto out_free;
> +
> + if (debug && map->count)
> + printk("%s: mapped first at gfn=%lx mfn=%lx\n", __func__,
> + page_to_pfn(map->pages[0].page),
> pfn_to_mfn(page_to_pfn(map->pages[0].page)));
> +
> + map->is_mapped = 1;
> +
> + for (i = 0; i < map->count; i++) {
> + if (map_ops[i].status) {
> + if (debug)
> + printk("%s: failed map at page %d: stat=%d\n",
> + __FUNCTION__, i, map_ops[i].status);
> + __free_page(map->pages[i].page);
> + map->pages[i].page = NULL;
> + err = -EINVAL;
> + } else {
> + map->pages[i].handle = map_ops[i].handle;
> + }
> + }
> +
> +out_free:
> + kfree(map_ops);
> +out:
> + if (!map->is_mapped)
> + atomic_sub(map->count, &pages_mapped);
> + return err;
> +}
> +
> +static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
> + struct ioctl_gntdev_map_grant_ref __user
> *u)
> +{
> + struct ioctl_gntdev_map_grant_ref op;
> + struct grant_map *map;
> + struct ioctl_gntdev_grant_ref* grants;
> + int err;
> +
> + if (copy_from_user(&op, u, sizeof(op)) != 0)
> + return -EFAULT;
> + if (debug)
> + printk("%s: priv %p, add %d\n", __FUNCTION__, priv,
> + op.count);
> + if (unlikely(op.count <= 0))
> + return -EINVAL;
> +
> + err = -ENOMEM;
> + grants = kmalloc(sizeof(grants[0]) * op.count, GFP_TEMPORARY);
> + if (!grants)
> + goto out_fail;
> +
> + err = -EFAULT;
> + if (copy_from_user(grants, u->refs, sizeof(grants[0]) * op.count))
> + goto out_free;
> +
> + map = gntdev_alloc_map(op.count, grants);
> + if (!map)
> + goto out_free;
> +
> + gntdev_add_map(priv, map);
> +
> + op.index = map->index << PAGE_SHIFT;
> +
> + err = -EFAULT;
> + if (copy_to_user(u, &op, sizeof(op)) != 0)
> + goto out_remove;
> +
> + err = 0;
> +
> +out_free:
> + kfree(grants);
> +out_fail:
> + return err;
> +
> +out_remove:
> + gntdev_del_map(priv, map);
> + gntdev_put_map(map);
> + goto out_free;
> +}
> +
> +static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
> + struct ioctl_gntdev_unmap_grant_ref
> __user *u)
> +{
> + struct ioctl_gntdev_unmap_grant_ref op;
> + struct grant_map *map;
> + int err = 0;
> +
> + if (copy_from_user(&op, u, sizeof(op)) != 0)
> + return -EFAULT;
> +
> + spin_lock(&priv->lock);
> + map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
> + if (map) {
> + __gntdev_del_map(priv, map);
> + } else
> + err = -EINVAL;
> + spin_unlock(&priv->lock);
> +
> + if (debug)
> + printk("%s: priv %p, del %d+%d = %p\n", __FUNCTION__, priv,
> + (int)op.index, (int)op.count, map);
> +
> + gntdev_put_map(map);
> + return err;
> +}
> +
> +static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
> + struct
> ioctl_gntdev_get_offset_for_vaddr __user *u)
> +{
> + struct ioctl_gntdev_get_offset_for_vaddr op;
> + struct vm_area_struct *vma;
> + struct grant_map *map;
> +
> + if (copy_from_user(&op, u, sizeof(op)) != 0)
> + return -EFAULT;
> + if (debug)
> + printk("%s: priv %p, offset for vaddr %lx\n", __FUNCTION__,
> priv,
> + (unsigned long)op.vaddr);
> +
> + vma = find_vma(current->mm, op.vaddr);
> + if (!vma)
> + return -EINVAL;
> +
> + map = vma->vm_private_data;
> + if (vma->vm_ops != &gntdev_vmops || !map)
> + return -EINVAL;
> +
> + op.offset = map->index << PAGE_SHIFT;
> + op.count = map->count;
> +
> + if (copy_to_user(u, &op, sizeof(op)) != 0)
> + return -EFAULT;
> + return 0;
> +}
> +
> +static long gntdev_ioctl(struct file *flip,
> + unsigned int cmd, unsigned long arg)
> +{
> + struct gntdev_priv *priv = flip->private_data;
> + void __user *ptr = (void __user *)arg;
> +
> + switch (cmd) {
> + case IOCTL_GNTDEV_MAP_GRANT_REF:
> + return gntdev_ioctl_map_grant_ref(priv, ptr);
> +
> + case IOCTL_GNTDEV_UNMAP_GRANT_REF:
> + return gntdev_ioctl_unmap_grant_ref(priv, ptr);
> +
> + case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
> + return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
> +
> + default:
> + if (debug)
> + printk("%s: priv %p, unknown cmd %x\n",
> + __FUNCTION__, priv, cmd);
> + return -ENOIOCTLCMD;
> + }
> +
> + return 0;
> +}
> +
> +static int gntdev_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> +{
> + struct grant_map *map = vma->vm_private_data;
> + pgoff_t pgoff = vmf->pgoff - vma->vm_pgoff;
> +
> + if (!map || !map->is_mapped || pgoff < 0 || pgoff > map->count) {
> + if (debug)
> + printk("%s: vaddr %p, pgoff %ld (shouldn't happen)\n",
> + __FUNCTION__, vmf->virtual_address, pgoff);
> + return VM_FAULT_SIGBUS;
> + }
> +
> + vmf->page = map->pages[pgoff].page;
> + get_page(vmf->page);
> + return 0;
> +}
> +
> +static void gntdev_vma_close(struct vm_area_struct *vma)
> +{
> + struct grant_map *map = vma->vm_private_data;
> + gntdev_put_map(map);
> +}
> +
> +static struct vm_operations_struct gntdev_vmops = {
> + .fault = gntdev_vma_fault,
> + .close = gntdev_vma_close,
> +};
> +
> +static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
> +{
> + struct gntdev_priv *priv = flip->private_data;
> + int index = vma->vm_pgoff;
> + int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> + struct grant_map *map;
> + int err = -EINVAL;
> +
> + if (!(vma->vm_flags & VM_SHARED))
> + return -EINVAL;
> +
> + spin_lock(&priv->lock);
> + map = gntdev_find_map_index(priv, index, count);
> +
> + if (debug)
> + printk("%s: map %d+%d at %lx (priv %p, map %p)\n", __func__,
> + index, count, vma->vm_start, priv, map);
> +
> + if (!map)
> + goto unlock_out;
> +
> + if (!map->is_mapped) {
> + map->is_ro = !(vma->vm_flags & VM_WRITE);
> + err = gntdev_do_map(map);
> + if (err)
> + goto unlock_out;
> + }
> +
> + if ((vma->vm_flags & VM_WRITE) && map->is_ro)
> + goto unlock_out;
> +
> + err = 0;
> + vma->vm_ops = &gntdev_vmops;
> +
> + vma->vm_flags |= VM_RESERVED;
> + vma->vm_flags |= VM_DONTEXPAND;
> + vma->vm_flags |= VM_IO;
> +
> + vma->vm_private_data = map;
> +
> + atomic_inc(&map->users);
> +
> +unlock_out:
> + spin_unlock(&priv->lock);
> + return err;
> +}
> +
> +static const struct file_operations gntdev_fops = {
> + .owner = THIS_MODULE,
> + .open = gntdev_open,
> + .release = gntdev_release,
> + .mmap = gntdev_mmap,
> + .unlocked_ioctl = gntdev_ioctl
> +};
> +
> +static struct miscdevice gntdev_miscdev = {
> + .minor = MISC_DYNAMIC_MINOR,
> + .name = "xen/gntdev",
> + .fops = &gntdev_fops,
> +};
> +
> +/* ------------------------------------------------------------------ */
> +
> +static int __init gntdev_init(void)
> +{
> + int err;
> +
> + if (!xen_domain())
> + return -ENODEV;
> +
> + if (!xen_feature(XENFEAT_auto_translated_physmap))
> + return -ENODEV;
> +
> + err = misc_register(&gntdev_miscdev);
> + if (err != 0) {
> + printk(KERN_ERR "Could not register gntdev device\n");
> + return err;
> + }
> + return 0;
> +}
> +
> +static void __exit gntdev_exit(void)
> +{
> + misc_deregister(&gntdev_miscdev);
> +}
> +
> +module_init(gntdev_init);
> +module_exit(gntdev_exit);
> +
> +/* ------------------------------------------------------------------ */
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index a73f07c..f6b98c0 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -626,6 +626,9 @@ static int __init gntdev_init(void)
> if (!xen_domain())
> return -ENODEV;
>
> + if (xen_feature(XENFEAT_auto_translated_physmap))
> + return -ENODEV;
> +
> err = misc_register(&gntdev_miscdev);
> if (err != 0) {
> printk(KERN_ERR "Could not register gntdev device\n");
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