On Thu, Sep 01, 2011 at 12:22:16PM -0400, Daniel De Graaf wrote:
> Normally, when a userspace process mapping a grant crashes, the domain
> providing the reference receives no indication that its peer has
> crashed, possibly leading to unexpected freezes or timeouts. This
> function provides a notification of the unmap by signalling an event
> channel and/or clearing a specific byte in the page.
>
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
> ---
> tools/libxc/xc_gnttab.c | 15 ++++++++++++
> tools/libxc/xc_linux_osdep.c | 52
> ++++++++++++++++++++++++++++++++++++++++++
> tools/libxc/xenctrl.h | 21 +++++++++++++++++
> tools/libxc/xenctrlosdep.h | 5 ++++
> 4 files changed, 93 insertions(+), 0 deletions(-)
>
> diff --git a/tools/libxc/xc_gnttab.c b/tools/libxc/xc_gnttab.c
> index 4f55fce..dc7aa0c 100644
> --- a/tools/libxc/xc_gnttab.c
> +++ b/tools/libxc/xc_gnttab.c
> @@ -174,6 +174,21 @@ void *xc_gnttab_map_domain_grant_refs(xc_gnttab *xcg,
> count, domid, refs,
> prot);
> }
>
> +void *xc_gnttab_map_grant_ref_notify(xc_gnttab *xcg,
> + uint32_t domid,
> + uint32_t ref,
> + uint32_t notify_offset,
> + evtchn_port_t notify_port)
> +{
> + if (xcg->ops->u.gnttab.map_grant_ref_notify)
> + return xcg->ops->u.gnttab.map_grant_ref_notify(xcg,
> xcg->ops_handle,
> + domid, ref, notify_offset, notify_port);
> + else
> + return xcg->ops->u.gnttab.map_grant_ref(xcg, xcg->ops_handle,
> + domid, ref, PROT_READ|PROT_WRITE);
> +}
> +
> +
> int xc_gnttab_munmap(xc_gnttab *xcg,
> void *start_address,
> uint32_t count)
> diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
> index dca6718..8f7718f 100644
> --- a/tools/libxc/xc_linux_osdep.c
> +++ b/tools/libxc/xc_linux_osdep.c
> @@ -613,6 +613,57 @@ static void
> *linux_gnttab_map_domain_grant_refs(xc_gnttab *xcg, xc_osdep_handle
> return do_gnttab_map_grant_refs(xcg, h, count, &domid, 0, refs, prot);
> }
>
> +static void *linux_gnttab_map_grant_ref_notify(xc_gnttab *xch,
> xc_osdep_handle h,
> + uint32_t domid, uint32_t ref,
> + uint32_t notify_offset,
> + evtchn_port_t notify_port)
> +{
> + int fd = (int)h;
> + struct ioctl_gntdev_map_grant_ref map;
> + struct ioctl_gntdev_unmap_notify notify;
That looks a bit odd. Like the formatting is off?
> + void *addr;
> +
> + map.count = 1;
> + map.refs[0].domid = domid;
> + map.refs[0].ref = ref;
> +
> + if ( ioctl(fd, IOCTL_GNTDEV_MAP_GRANT_REF, &map) ) {
> + PERROR("xc_gnttab_map_grant_ref: ioctl MAP_GRANT_REF failed");
> + return NULL;
> + }
> +
> + addr = mmap(NULL, XC_PAGE_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd,
> map.index);
> + if ( addr == MAP_FAILED )
> + {
> + int saved_errno = errno;
> + struct ioctl_gntdev_unmap_grant_ref unmap_grant;
> +
> + PERROR("xc_gnttab_map_grant_ref: mmap failed");
> + unmap_grant.index = map.index;
> + unmap_grant.count = 1;
> + ioctl(fd, IOCTL_GNTDEV_UNMAP_GRANT_REF, &unmap_grant);
> + errno = saved_errno;
> + return NULL;
> + }
> +
> + notify.index = map.index;
> + notify.action = 0;
> + if (notify_offset >= 0) {
> + notify.index += notify_offset;
> + notify.action |= UNMAP_NOTIFY_CLEAR_BYTE;
> + }
> + if (notify_port >= 0) {
> + notify.event_channel_port = notify_port;
> + notify.action |= UNMAP_NOTIFY_SEND_EVENT;
> + }
> + if (notify.action && ioctl(fd, IOCTL_GNTDEV_SET_UNMAP_NOTIFY, ¬ify)) {
> + PERROR("linux_gnttab_map_grant_ref_notify: ioctl SET_UNMAP_NOTIFY
> failed");
Perhaps reporting via an argument that we failed at doing the notify would
be useful? That way at least you know you need to do polling.
> + }
> +
> + return addr;
> +}
> +
> +
> static int linux_gnttab_munmap(xc_gnttab *xcg, xc_osdep_handle h,
> void *start_address, uint32_t count)
> {
> @@ -662,6 +713,7 @@ static struct xc_osdep_ops linux_gnttab_ops = {
> .map_grant_ref = &linux_gnttab_map_grant_ref,
> .map_grant_refs = &linux_gnttab_map_grant_refs,
> .map_domain_grant_refs = &linux_gnttab_map_domain_grant_refs,
> + .map_grant_ref_notify = &linux_gnttab_map_grant_ref_notify,
> .munmap = &linux_gnttab_munmap,
> },
> };
> diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
> index 1b82ee0..7859571 100644
> --- a/tools/libxc/xenctrl.h
> +++ b/tools/libxc/xenctrl.h
> @@ -1349,6 +1349,27 @@ void *xc_gnttab_map_domain_grant_refs(xc_gnttab *xcg,
> int prot);
>
> /*
> + * Memory maps a grant reference from one domain to a local address range.
> + * Mappings should be unmapped with xc_gnttab_munmap. Logs errors.
^^^^^^^^^^^^ .. that
looks odd?
> + * This version always maps writable pages, and will attempt to set up
> + * an unmap notification at the given offset and event channel. When the
> + * page is unmapped, the byte at the given offset will be zeroed and a
> + * wakeup will be sent to the given event channel.
> + *
> + * @parm xcg a handle on an open grant table interface
> + * @parm domid the domain to map memory from
> + * @parm ref the grant reference ID to map
> + * @parm notify_offset The byte offset in the page to use for unmap
> + * notification; -1 for none.
> + * @parm notify_port The event channel port to use for unmap notify, or -1
> + */
> +void *xc_gnttab_map_grant_ref_notify(xc_gnttab *xcg,
> + uint32_t domid,
> + uint32_t ref,
> + uint32_t notify_offset,
> + evtchn_port_t notify_port);
> +
> +/*
> * Unmaps the @count pages starting at @start_address, which were mapped by a
> * call to xc_gnttab_map_grant_ref or xc_gnttab_map_grant_refs. Never logs.
> */
> diff --git a/tools/libxc/xenctrlosdep.h b/tools/libxc/xenctrlosdep.h
> index bfe46e0..01969c5 100644
> --- a/tools/libxc/xenctrlosdep.h
> +++ b/tools/libxc/xenctrlosdep.h
> @@ -119,6 +119,11 @@ struct xc_osdep_ops
> uint32_t domid,
> uint32_t *refs,
> int prot);
> + void *(*map_grant_ref_notify)(xc_gnttab *xcg, xc_osdep_handle h,
> + uint32_t domid,
> + uint32_t ref,
> + uint32_t notify_offset,
> + evtchn_port_t notify_port);
> int (*munmap)(xc_gnttab *xcg, xc_osdep_handle h,
> void *start_address,
> uint32_t count);
> --
> 1.7.6
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home