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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2 of 2] xenpaging: handle GNTST_eagain in kernel drivers
On Thu, Dec 01, 2011 at 03:51:55PM -0500, Andres Lagar-Cavilla wrote:
> drivers/xen/blkback/blkback.c | 6 ++-
> drivers/xen/blkback/interface.c | 9 +++-
> drivers/xen/core/gnttab.c | 4 +-
> drivers/xen/gntdev/gntdev.c | 49
> +++++++++++++++++------------
> drivers/xen/netback/interface.c | 5 +-
> drivers/xen/netback/netback.c | 16 ++++++---
> drivers/xen/scsiback/interface.c | 10 +++---
> drivers/xen/scsiback/scsiback.c | 4 +-
> drivers/xen/tpmback/interface.c | 7 +--
> drivers/xen/tpmback/tpmback.c | 20 ++++-------
> drivers/xen/usbback/interface.c | 16 ++++----
> drivers/xen/usbback/usbback.c | 4 +-
> drivers/xen/xenbus/xenbus_backend_client.c | 10 +++---
> include/xen/gnttab.h | 37 ++++++++++++++++++++++
> 14 files changed, 126 insertions(+), 71 deletions(-)
>
>
> Handle GNTST_eagain status from GNTTABOP_map_grant_ref and
> GNTTABOP_copy operations properly to allow usage of xenpaging without
> causing crashes or data corruption.
>
> Replace all relevant HYPERVISOR_grant_table_op() calls with a retry
> loop. This loop is implemented as a macro to allow different
> GNTTABOP_* args. It will sleep up to 33 seconds and wait for the
> page to be paged in again.
>
> All ->status checks were updated to use the GNTST_* namespace. All
> return values are converted from GNTST_* namespace to 0/-EINVAL, since
> all callers did not use the actual return value.
Any plans to do this for the pvops tree?
>
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> Acked-by: Patrick Colp <pjcolp@xxxxxxxxx>
>
> This is a port from xenlinux 2.6.18 to the 2.6.32 xcp tree
> Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/blkback/blkback.c
> --- a/drivers/xen/blkback/blkback.c
> +++ b/drivers/xen/blkback/blkback.c
> @@ -701,11 +701,13 @@ static void dispatch_rw_block_io(blkif_t
> BUG_ON(ret);
>
> for (i = 0; i < nseg; i++) {
> - if (unlikely(map[i].status != 0)) {
> + if (unlikely(map[i].status == GNTST_eagain))
> +
> gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &map[i]);
> + if (unlikely(map[i].status != GNTST_okay)) {
> DPRINTK("grant map of dom %u gref %u failed: status
> %d\n",
> blkif->domid, req->seg[i].gref, map[i].status);
> map[i].handle = BLKBACK_INVALID_HANDLE;
> - ret |= 1;
> + ret = 1;
> continue;
> }
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/blkback/interface.c
> --- a/drivers/xen/blkback/interface.c
> +++ b/drivers/xen/blkback/interface.c
> @@ -95,7 +95,7 @@ static int map_frontend_pages(blkif_t *b
> struct vm_struct *area = blkif->blk_ring_area;
> struct gnttab_map_grant_ref op[BLKIF_MAX_RING_PAGES];
> unsigned int i;
> - int status = 0;
> + int status = GNTST_okay;
>
> for (i = 0; i < nr_shared_pages; i++) {
> unsigned long addr = (unsigned long)area->addr +
> @@ -110,7 +110,10 @@ static int map_frontend_pages(blkif_t *b
> BUG();
>
> for (i = 0; i < nr_shared_pages; i++) {
> - if ((status = op[i].status) != 0) {
> + if (op[i].status == GNTST_eagain)
> +
> gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op[i]);
> + if (op[i].status != GNTST_okay) {
> + status = op[i].status;
> blkif->shmem_handle[i] = INVALID_GRANT_HANDLE;
> continue;
> }
> @@ -120,7 +123,7 @@ static int map_frontend_pages(blkif_t *b
>
> blkif->nr_shared_pages = nr_shared_pages;
>
> - if (status != 0) {
> + if (status != GNTST_okay) {
> DPRINTK(" Grant table operation failure !\n");
> unmap_frontend_pages(blkif);
> }
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/core/gnttab.c
> --- a/drivers/xen/core/gnttab.c
> +++ b/drivers/xen/core/gnttab.c
> @@ -773,7 +773,7 @@ static int gnttab_map(unsigned int start
> return -ENOSYS;
> }
>
> - BUG_ON(rc || setup.status);
> + BUG_ON(rc || (setup.status != GNTST_okay));
>
> if (shared.raw == NULL)
> shared.raw = arch_gnttab_alloc_shared(gframes);
> @@ -901,7 +901,7 @@ int gnttab_copy_grant_page(grant_ref_t r
> err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_and_replace,
> &unmap, 1);
> BUG_ON(err);
> - BUG_ON(unmap.status);
> + BUG_ON(unmap.status != GNTST_okay);
>
> write_sequnlock_irq(&gnttab_dma_lock);
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/gntdev/gntdev.c
> --- a/drivers/xen/gntdev/gntdev.c
> +++ b/drivers/xen/gntdev/gntdev.c
> @@ -503,7 +503,7 @@ static int gntdev_mmap (struct file *fli
> uint64_t ptep;
> int ret;
> int flags;
> - int i;
> + int i, exit_ret;
> struct page *page;
> gntdev_file_private_data_t *private_data = flip->private_data;
>
> @@ -578,6 +578,7 @@ static int gntdev_mmap (struct file *fli
> vma->vm_mm->context.has_foreign_mappings = 1;
> #endif
>
> + exit_ret = -ENOMEM;
> for (i = 0; i < size; ++i) {
>
> flags = GNTMAP_host_map;
> @@ -598,14 +599,18 @@ static int gntdev_mmap (struct file *fli
> ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
> &op, 1);
> BUG_ON(ret);
> - if (op.status) {
> - printk(KERN_ERR "Error mapping the grant reference "
> - "into the kernel (%d). domid = %d; ref = %d\n",
> - op.status,
> - private_data->grants[slot_index+i]
> - .u.valid.domid,
> - private_data->grants[slot_index+i]
> - .u.valid.ref);
> + if (op.status != GNTST_okay) {
> + if (op.status != GNTST_eagain)
> + printk(KERN_ERR "Error mapping the grant
> reference "
> + "into the kernel (%d). domid = %d;
> ref = %d\n",
> + op.status,
> + private_data->grants[slot_index+i]
> + .u.valid.domid,
> + private_data->grants[slot_index+i]
> + .u.valid.ref);
> + else
> + /* Propagate instead of trying to fix it up */
> + exit_ret = -EAGAIN;
> goto undo_map_out;
> }
>
> @@ -674,14 +679,17 @@ static int gntdev_mmap (struct file *fli
> ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
> &op, 1);
> BUG_ON(ret);
> - if (op.status) {
> + if (op.status != GNTST_okay) {
> printk(KERN_ERR "Error mapping the grant "
> - "reference into user space (%d). domid "
> - "= %d; ref = %d\n", op.status,
> - private_data->grants[slot_index+i].u
> - .valid.domid,
> - private_data->grants[slot_index+i].u
> - .valid.ref);
> + "reference into user space (%d).
> domid "
> + "= %d; ref = %d\n", op.status,
> + private_data->grants[slot_index+i].u
> + .valid.domid,
> + private_data->grants[slot_index+i].u
> + .valid.ref);
> + /* GNTST_eagain (i.e. page paged out) sohuld
> never happen
> + * once we've mapped into kernel space */
> + BUG_ON(op.status == GNTST_eagain);
> goto undo_map_out;
> }
>
> @@ -705,9 +713,10 @@ static int gntdev_mmap (struct file *fli
> }
>
> }
> + exit_ret = 0;
>
> up_write(&private_data->grants_sem);
> - return 0;
> + return exit_ret;
>
> undo_map_out:
> /* If we have a mapping failure, the unmapping will be taken care of
> @@ -725,7 +734,7 @@ undo_map_out:
>
> up_write(&private_data->grants_sem);
>
> - return -ENOMEM;
> + return exit_ret;
> }
>
> static pte_t gntdev_clear_pte(struct vm_area_struct *vma, unsigned long addr,
> @@ -777,7 +786,7 @@ static pte_t gntdev_clear_pte(struct vm_
> ret = HYPERVISOR_grant_table_op(
> GNTTABOP_unmap_grant_ref, &op, 1);
> BUG_ON(ret);
> - if (op.status)
> + if (op.status != GNTST_okay)
> printk("User unmap grant status = %d\n",
> op.status);
> } else {
> @@ -794,7 +803,7 @@ static pte_t gntdev_clear_pte(struct vm_
> ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
> &op, 1);
> BUG_ON(ret);
> - if (op.status)
> + if (op.status != GNTST_okay)
> printk("Kernel unmap grant status = %d\n", op.status);
>
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/netback/interface.c
> --- a/drivers/xen/netback/interface.c
> +++ b/drivers/xen/netback/interface.c
> @@ -381,10 +381,9 @@ static int map_frontend_pages(struct xen
> gnttab_set_map_op(&op, (unsigned long)comms->ring_area->addr,
> GNTMAP_host_map, ring_ref, domid);
>
> - if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> - BUG();
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> - if (op.status) {
> + if (op.status != GNTST_okay) {
> DPRINTK(" Gnttab failure mapping ring_ref!\n");
> free_vm_area(comms->ring_area);
> return op.status;
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/netback/netback.c
> --- a/drivers/xen/netback/netback.c
> +++ b/drivers/xen/netback/netback.c
> @@ -419,11 +419,13 @@ static int netbk_check_gop(int nr_copy_s
>
> for (i = 0; i < nr_copy_slots; i++) {
> copy_op = npo->copy + npo->copy_cons++;
> + if (copy_op->status == GNTST_eagain)
> + gnttab_check_GNTST_eagain_while(GNTTABOP_copy, copy_op);
> if (copy_op->status != GNTST_okay) {
> - DPRINTK("Bad status %d from copy to DOM%d.\n",
> - copy_op->status, domid);
> - status = NETIF_RSP_ERROR;
> - }
> + DPRINTK("Bad status %d from copy to DOM%d.\n",
> + copy_op->status, domid);
> + status = NETIF_RSP_ERROR;
> + }
> }
>
> return status;
> @@ -1020,7 +1022,11 @@ static int netbk_tx_check_mop(struct xen
>
> /* Check status of header. */
> err = mop->status;
> - if (unlikely(err)) {
> + if (err == GNTST_eagain) {
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, mop);
> + err = mop->status;
> + }
> + if (unlikely(err != GNTST_okay)) {
> pending_ring_idx_t index;
> index = pending_index(netbk->pending_prod++);
> txp = &pending_tx_info[pending_idx].req;
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/scsiback/interface.c
> --- a/drivers/xen/scsiback/interface.c
> +++ b/drivers/xen/scsiback/interface.c
> @@ -69,18 +69,18 @@ static int map_frontend_page( struct vsc
> GNTMAP_host_map, ring_ref,
> info->domid);
>
> - err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
> - BUG_ON(err);
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> - if (op.status) {
> - printk(KERN_ERR "scsiback: Grant table operation failure !\n");
> + if (op.status != GNTST_okay) {
> + printk(KERN_ERR "scsiback: Grant table operation failure
> %d!\n",
> + (int) op.status);
> return op.status;
> }
>
> info->shmem_ref = ring_ref;
> info->shmem_handle = op.handle;
>
> - return (GNTST_okay);
> + return 0;
> }
>
> static void unmap_frontend_page(struct vscsibk_info *info)
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/scsiback/scsiback.c
> --- a/drivers/xen/scsiback/scsiback.c
> +++ b/drivers/xen/scsiback/scsiback.c
> @@ -287,7 +287,9 @@ static int scsiback_gnttab_data_map(vscs
> for_each_sg (pending_req->sgl, sg, nr_segments, i) {
> struct page *pg;
>
> - if (unlikely(map[i].status != 0)) {
> + if (unlikely(map[i].status == GNTST_eagain))
> +
> gnttab_check_GNTST_eagain_while(GNTTABOP_map_grant_ref, &map[i]);
> + if (unlikely(map[i].status != GNTST_okay)) {
> printk(KERN_ERR "scsiback: invalid buffer --
> could not remap it\n");
> map[i].handle = SCSIBACK_INVALID_HANDLE;
> err |= 1;
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/tpmback/interface.c
> --- a/drivers/xen/tpmback/interface.c
> +++ b/drivers/xen/tpmback/interface.c
> @@ -86,11 +86,10 @@ static int map_frontend_page(tpmif_t *tp
> gnttab_set_map_op(&op, (unsigned long)tpmif->tx_area->addr,
> GNTMAP_host_map, shared_page, tpmif->domid);
>
> - if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> - BUG();
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> - if (op.status) {
> - DPRINTK(" Grant table operation failure !\n");
> + if (op.status != GNTST_okay) {
> + DPRINTK(" Grant table operation failure %d!\n", (int)
> op.status);
> return op.status;
> }
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/tpmback/tpmback.c
> --- a/drivers/xen/tpmback/tpmback.c
> +++ b/drivers/xen/tpmback/tpmback.c
> @@ -256,15 +256,13 @@ int _packet_write(struct packet *pak,
> gnttab_set_map_op(&map_op, idx_to_kaddr(tpmif, i),
> GNTMAP_host_map, tx->ref, tpmif->domid);
>
> - if (unlikely(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
> - &map_op, 1))) {
> - BUG();
> - }
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref,
> &map_op);
>
> handle = map_op.handle;
>
> - if (map_op.status) {
> - DPRINTK(" Grant table operation failure !\n");
> + if (map_op.status != GNTST_okay) {
> + DPRINTK(" Grant table operation failure %d!\n",
> + (int) map_op.status);
> return 0;
> }
>
> @@ -394,13 +392,11 @@ static int packet_read_shmem(struct pack
> gnttab_set_map_op(&map_op, idx_to_kaddr(tpmif, i),
> GNTMAP_host_map, tx->ref, tpmif->domid);
>
> - if (unlikely(HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
> - &map_op, 1))) {
> - BUG();
> - }
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref,
> &map_op);
>
> - if (map_op.status) {
> - DPRINTK(" Grant table operation failure !\n");
> + if (map_op.status != GNTST_okay) {
> + DPRINTK(" Grant table operation failure %d!\n",
> + (int) map_op.status);
> return -EFAULT;
> }
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/usbback/interface.c
> --- a/drivers/xen/usbback/interface.c
> +++ b/drivers/xen/usbback/interface.c
> @@ -109,11 +109,11 @@ static int map_frontend_pages(usbif_t *u
> gnttab_set_map_op(&op, (unsigned long)usbif->urb_ring_area->addr,
> GNTMAP_host_map, urb_ring_ref, usbif->domid);
>
> - if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> - BUG();
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> - if (op.status) {
> - printk(KERN_ERR "grant table failure mapping urb_ring_ref\n");
> + if (op.status != GNTST_okay) {
> + printk(KERN_ERR "grant table failure mapping urb_ring_ref %d\n",
> + (int) op.status);
> return op.status;
> }
>
> @@ -123,17 +123,17 @@ static int map_frontend_pages(usbif_t *u
> gnttab_set_map_op(&op, (unsigned long)usbif->conn_ring_area->addr,
> GNTMAP_host_map, conn_ring_ref, usbif->domid);
>
> - if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> - BUG();
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> - if (op.status) {
> + if (op.status != GNTST_okay) {
> struct gnttab_unmap_grant_ref unop;
> gnttab_set_unmap_op(&unop,
> (unsigned long) usbif->urb_ring_area->addr,
> GNTMAP_host_map, usbif->urb_shmem_handle);
> VOID(HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &unop,
> 1));
> - printk(KERN_ERR "grant table failure mapping conn_ring_ref\n");
> + printk(KERN_ERR "grant table failure mapping conn_ring_ref
> %d\n",
> + (int) op.status);
> return op.status;
> }
>
> diff -r df9e25a0189b -r 1170bc32db41 drivers/xen/usbback/usbback.c
> --- a/drivers/xen/usbback/usbback.c
> +++ b/drivers/xen/usbback/usbback.c
> @@ -428,7 +428,9 @@ static int usbbk_gnttab_map(usbif_t *usb
> BUG_ON(ret);
>
> for (i = 0; i < nr_segs; i++) {
> - if (unlikely(map[i].status != 0)) {
> + if (unlikely(map[i].status == GNTST_eagain))
> +
> gnttab_check_GNTST_eagain_while(GNTTABOP_map_grant_ref, &map[i]);
> + if (unlikely(map[i].status != GNTST_okay)) {
> printk(KERN_ERR "usbback: invalid buffer --
> could not remap it\n");
> map[i].handle = USBBACK_INVALID_HANDLE;
> ret |= 1;
> diff -r df9e25a0189b -r 1170bc32db41
> drivers/xen/xenbus/xenbus_backend_client.c
> --- a/drivers/xen/xenbus/xenbus_backend_client.c
> +++ b/drivers/xen/xenbus/xenbus_backend_client.c
> @@ -48,8 +48,7 @@ struct vm_struct *xenbus_map_ring_valloc
> gnttab_set_map_op(&op, (unsigned long)area->addr, GNTMAP_host_map,
> gnt_ref, dev->otherend_id);
>
> - if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> - BUG();
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> if (op.status != GNTST_okay) {
> free_vm_area(area);
> @@ -75,15 +74,16 @@ int xenbus_map_ring(struct xenbus_device
>
> gnttab_set_map_op(&op, (unsigned long)vaddr, GNTMAP_host_map,
> gnt_ref, dev->otherend_id);
> - if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
> - BUG();
> + gnttab_check_GNTST_eagain_do_while(GNTTABOP_map_grant_ref, &op);
>
> if (op.status != GNTST_okay) {
> xenbus_dev_fatal(dev, op.status,
> "mapping in shared page %d from domain %d",
> gnt_ref, dev->otherend_id);
> - } else
> + } else {
> *handle = op.handle;
> + return 0;
> + }
>
> return op.status;
> }
> diff -r df9e25a0189b -r 1170bc32db41 include/xen/gnttab.h
> --- a/include/xen/gnttab.h
> +++ b/include/xen/gnttab.h
> @@ -187,4 +187,41 @@ gnttab_set_replace_op(struct gnttab_unma
> unmap->handle = handle;
> }
>
> +#define gnttab_check_GNTST_eagain_while(__HCop, __HCarg_p)
> \
> +do {
> \
> + u8 __hc_delay = 1;
> \
> + int __ret;
> \
> + while (unlikely((__HCarg_p)->status == GNTST_eagain && __hc_delay)) {
> \
> + msleep(__hc_delay++);
> \
> + __ret = HYPERVISOR_grant_table_op(__HCop, (__HCarg_p), 1);
> \
> + BUG_ON(__ret);
> \
> + }
> \
> + if (__hc_delay == 0) {
> \
> + printk(KERN_ERR "%s: %s gnt busy\n", __func__, current->comm);
> \
> + (__HCarg_p)->status = GNTST_bad_page;
> \
> + }
> \
> + if ((__HCarg_p)->status != GNTST_okay)
> \
> + printk(KERN_ERR "%s: %s gnt status %x\n",
> \
> + __func__, current->comm, (__HCarg_p)->status);
> \
> +} while(0)
> +
> +#define gnttab_check_GNTST_eagain_do_while(__HCop, __HCarg_p)
> \
> +do {
> \
> + u8 __hc_delay = 1;
> \
> + int __ret;
> \
> + do {
> \
> + __ret = HYPERVISOR_grant_table_op(__HCop, (__HCarg_p), 1);
> \
> + BUG_ON(__ret);
> \
> + if ((__HCarg_p)->status == GNTST_eagain)
> \
> + msleep(__hc_delay++);
> \
> + } while ((__HCarg_p)->status == GNTST_eagain && __hc_delay);
> \
> + if (__hc_delay == 0) {
> \
> + printk(KERN_ERR "%s: %s gnt busy\n", __func__, current->comm);
> \
> + (__HCarg_p)->status = GNTST_bad_page;
> \
> + }
> \
> + if ((__HCarg_p)->status != GNTST_okay)
> \
> + printk(KERN_ERR "%s: %s gnt status %x\n",
> \
> + __func__, current->comm, (__HCarg_p)->status);
> \
> +} while(0)
> +
> #endif /* __ASM_GNTTAB_H__ */
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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