# HG changeset patch
# User Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
# Date 1317925733 -3600
# Node ID aea2b06769f3c7659ee1ee3601bb9bc01781665e
# Parent 19d2922bcfb9f5337b794213ac3a6d4c08472dae
libxc: add xc_gnttab_map_grant_ref_notify
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.
This also unifies the 3 very similar grant-mapping osdep interfaces into
a single function instead of introducing yet another minor variation.
Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
diff -r 19d2922bcfb9 -r aea2b06769f3 tools/include/xen-sys/Linux/gntdev.h
--- a/tools/include/xen-sys/Linux/gntdev.h Thu Oct 06 19:11:51 2011 +0100
+++ b/tools/include/xen-sys/Linux/gntdev.h Thu Oct 06 19:28:53 2011 +0100
@@ -66,7 +66,7 @@
* before this ioctl is called, or an error will result.
*/
#define IOCTL_GNTDEV_UNMAP_GRANT_REF \
-_IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref))
+_IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref))
struct ioctl_gntdev_unmap_grant_ref {
/* IN parameters */
/* The offset was returned by the corresponding map operation. */
@@ -116,4 +116,35 @@
uint32_t count;
};
+/*
+ * Sets up an unmap notification within the page, so that the other side can do
+ * cleanup if this side crashes. Required to implement cross-domain robust
+ * mutexes or close notification on communication channels.
+ *
+ * Each mapped page only supports one notification; multiple calls referring to
+ * the same page overwrite the previous notification. You must clear the
+ * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
+ * to occur.
+ */
+#define IOCTL_GNTDEV_SET_UNMAP_NOTIFY \
+_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify))
+struct ioctl_gntdev_unmap_notify {
+ /* IN parameters */
+ /* Offset in the file descriptor for a byte within the page. This offset
+ * is the result of the IOCTL_GNTDEV_MAP_GRANT_REF and is the same as
+ * is used with mmap(). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the
byte
+ * within the page to be cleared.
+ */
+ uint64_t index;
+ /* Action(s) to take on unmap */
+ uint32_t action;
+ /* Event channel to notify */
+ uint32_t event_channel_port;
+};
+
+/* Clear (set to zero) the byte specified by index */
+#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
+/* Send an interrupt on the indicated event channel */
+#define UNMAP_NOTIFY_SEND_EVENT 0x2
+
#endif /* __LINUX_PUBLIC_GNTDEV_H__ */
diff -r 19d2922bcfb9 -r aea2b06769f3 tools/libxc/xc_gnttab.c
--- a/tools/libxc/xc_gnttab.c Thu Oct 06 19:11:51 2011 +0100
+++ b/tools/libxc/xc_gnttab.c Thu Oct 06 19:28:53 2011 +0100
@@ -18,6 +18,7 @@
*/
#include "xc_private.h"
+#include <errno.h>
int xc_gnttab_op(xc_interface *xch, int cmd, void * op, int op_size, int count)
{
@@ -150,8 +151,8 @@
uint32_t ref,
int prot)
{
- return xcg->ops->u.gnttab.map_grant_ref(xcg, xcg->ops_handle,
- domid, ref, prot);
+ return xcg->ops->u.gnttab.grant_map(xcg, xcg->ops_handle, 1, 0, prot,
+ &domid, &ref, -1, -1);
}
void *xc_gnttab_map_grant_refs(xc_gnttab *xcg,
@@ -160,8 +161,8 @@
uint32_t *refs,
int prot)
{
- return xcg->ops->u.gnttab.map_grant_refs(xcg, xcg->ops_handle,
- count, domids, refs, prot);
+ return xcg->ops->u.gnttab.grant_map(xcg, xcg->ops_handle, count, 0,
+ prot, domids, refs, -1, -1);
}
void *xc_gnttab_map_domain_grant_refs(xc_gnttab *xcg,
@@ -170,10 +171,23 @@
uint32_t *refs,
int prot)
{
- return xcg->ops->u.gnttab.map_domain_grant_refs(xcg, xcg->ops_handle,
- count, domid, refs,
prot);
+ return xcg->ops->u.gnttab.grant_map(xcg, xcg->ops_handle, count,
+ XC_GRANT_MAP_SINGLE_DOMAIN,
+ prot, &domid, refs, -1, -1);
}
+void *xc_gnttab_map_grant_ref_notify(xc_gnttab *xcg,
+ uint32_t domid,
+ uint32_t ref,
+ int prot,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port)
+{
+ return xcg->ops->u.gnttab.grant_map(xcg, xcg->ops_handle, 1, 0, prot,
+ &domid, &ref, notify_offset, notify_port);
+}
+
+
int xc_gnttab_munmap(xc_gnttab *xcg,
void *start_address,
uint32_t count)
diff -r 19d2922bcfb9 -r aea2b06769f3 tools/libxc/xc_linux_osdep.c
--- a/tools/libxc/xc_linux_osdep.c Thu Oct 06 19:11:51 2011 +0100
+++ b/tools/libxc/xc_linux_osdep.c Thu Oct 06 19:28:53 2011 +0100
@@ -509,56 +509,21 @@
return close(fd);
}
-static void *linux_gnttab_map_grant_ref(xc_gnttab *xch, xc_osdep_handle h,
- uint32_t domid, uint32_t ref, int prot)
-{
- int fd = (int)h;
- struct ioctl_gntdev_map_grant_ref map;
- 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;
- }
-
-mmap_again:
- addr = mmap(NULL, XC_PAGE_SIZE, prot, MAP_SHARED, fd, map.index);
- if ( addr == MAP_FAILED )
- {
- int saved_errno = errno;
- struct ioctl_gntdev_unmap_grant_ref unmap_grant;
-
- if(saved_errno == EAGAIN)
- {
- usleep(1000);
- goto mmap_again;
- }
- /* Unmap the driver slots used to store the grant information. */
- 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;
- }
-
- return addr;
-}
-
-static void *do_gnttab_map_grant_refs(xc_gnttab *xch, xc_osdep_handle h,
- uint32_t count,
- uint32_t *domids, int domids_stride,
- uint32_t *refs, int prot)
+static void *linux_gnttab_grant_map(xc_gnttab *xch, xc_osdep_handle h,
+ uint32_t count, int flags, int prot,
+ uint32_t *domids, uint32_t *refs,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port)
{
int fd = (int)h;
struct ioctl_gntdev_map_grant_ref *map;
void *addr = NULL;
+ int domids_stride = 1;
int i;
+ if (flags & XC_GRANT_MAP_SINGLE_DOMAIN)
+ domids_stride = 0;
+
map = malloc(sizeof(*map) +
(count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
if ( map == NULL )
@@ -573,13 +538,52 @@
map->count = count;
if ( ioctl(fd, IOCTL_GNTDEV_MAP_GRANT_REF, map) ) {
- PERROR("xc_gnttab_map_grant_refs: ioctl MAP_GRANT_REF failed");
+ PERROR("linux_gnttab_grant_map: ioctl MAP_GRANT_REF failed");
goto out;
}
+ retry:
addr = mmap(NULL, XC_PAGE_SIZE * count, prot, MAP_SHARED, fd,
map->index);
- if ( addr == MAP_FAILED )
+
+ if (addr == MAP_FAILED && errno == EAGAIN)
+ {
+ /*
+ * The grant hypercall can return EAGAIN if the granted page is
+ * swapped out. Since the paging daemon may be in the same domain, the
+ * hypercall cannot block without causing a deadlock.
+ *
+ * Because there are no notificaitons when the page is swapped in, wait
+ * a bit before retrying, and hope that the page will arrive
eventually.
+ */
+ usleep(1000);
+ goto retry;
+ }
+
+ if (addr != MAP_FAILED)
+ {
+ int rv = 0;
+ struct ioctl_gntdev_unmap_notify notify;
+ notify.index = map->index;
+ notify.action = 0;
+ if (notify_offset >= 0 && notify_offset < XC_PAGE_SIZE * count) {
+ notify.index += notify_offset;
+ notify.action |= UNMAP_NOTIFY_CLEAR_BYTE;
+ }
+ if (notify_port != -1) {
+ notify.event_channel_port = notify_port;
+ notify.action |= UNMAP_NOTIFY_SEND_EVENT;
+ }
+ if (notify.action)
+ rv = ioctl(fd, IOCTL_GNTDEV_SET_UNMAP_NOTIFY, ¬ify);
+ if (rv) {
+ PERROR("linux_gnttab_grant_map: ioctl SET_UNMAP_NOTIFY failed");
+ munmap(addr, count * XC_PAGE_SIZE);
+ addr = MAP_FAILED;
+ }
+ }
+
+ if (addr == MAP_FAILED)
{
int saved_errno = errno;
struct ioctl_gntdev_unmap_grant_ref unmap_grant;
@@ -599,19 +603,7 @@
return addr;
}
-static void *linux_gnttab_map_grant_refs(xc_gnttab *xcg, xc_osdep_handle h,
- uint32_t count, uint32_t *domids,
- uint32_t *refs, int prot)
-{
- return do_gnttab_map_grant_refs(xcg, h, count, domids, 1, refs, prot);
-}
-static void *linux_gnttab_map_domain_grant_refs(xc_gnttab *xcg,
xc_osdep_handle h,
- uint32_t count,
- uint32_t domid, uint32_t
*refs, int prot)
-{
- return do_gnttab_map_grant_refs(xcg, h, count, &domid, 0, refs, prot);
-}
static int linux_gnttab_munmap(xc_gnttab *xcg, xc_osdep_handle h,
void *start_address, uint32_t count)
@@ -659,9 +651,7 @@
.close = &linux_gnttab_close,
.u.gnttab = {
- .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,
+ .grant_map = &linux_gnttab_grant_map,
.munmap = &linux_gnttab_munmap,
},
};
diff -r 19d2922bcfb9 -r aea2b06769f3 tools/libxc/xc_minios.c
--- a/tools/libxc/xc_minios.c Thu Oct 06 19:11:51 2011 +0100
+++ b/tools/libxc/xc_minios.c Thu Oct 06 19:28:53 2011 +0100
@@ -458,45 +458,23 @@
files[fd].type = FTYPE_NONE;
}
-static void *minios_gnttab_map_grant_ref(xc_gnttab *xcg, xc_osdep_handle h,
- uint32_t domid,
- uint32_t ref,
- int prot)
+static void *minios_gnttab_grant_map(xc_gnttab *xcg, xc_osdep_handle h,
+ uint32_t count, int flags, int prot,
+ uint32_t *domids, uint32_t *refs,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port)
{
int fd = (int)h;
+ int stride = 1;
+ if (flags & XC_GRANT_MAP_SINGLE_DOMAIN)
+ stride = 0;
+ if (notify_offset != -1 || notify_port != -1) {
+ errno = ENOSYS;
+ return NULL;
+ }
return gntmap_map_grant_refs(&files[fd].gntmap,
- 1,
- &domid, 0,
- &ref,
- prot & PROT_WRITE);
-}
-
-static void *minios_gnttab_map_grant_refs(xc_gnttab *xcg, xc_osdep_handle h,
- uint32_t count,
- uint32_t *domids,
- uint32_t *refs,
- int prot)
-{
- int fd = (int)h;
- return gntmap_map_grant_refs(&files[fd].gntmap,
- count,
- domids, 1,
- refs,
- prot & PROT_WRITE);
-}
-
-static void *minios_gnttab_map_domain_grant_refs(xc_gnttab *xcg,
xc_osdep_handle h,
- uint32_t count,
- uint32_t domid,
- uint32_t *refs,
- int prot)
-{
- int fd = (int)h;
- return gntmap_map_grant_refs(&files[fd].gntmap,
- count,
- &domid, 0,
- refs,
- prot & PROT_WRITE);
+ count, domids, stride,
+ refs, prot & PROT_WRITE);
}
static int minios_gnttab_munmap(xc_gnttab *xcg, xc_osdep_handle h,
@@ -534,9 +512,7 @@
.close = &minios_gnttab_close,
.u.gnttab = {
- .map_grant_ref = &minios_gnttab_map_grant_ref,
- .map_grant_refs = &minios_gnttab_map_grant_refs,
- .map_domain_grant_refs = &minios_gnttab_map_domain_grant_refs,
+ .grant_map = &minios_gnttab_grant_map,
.munmap = &minios_gnttab_munmap,
.set_max_grants = &minios_gnttab_set_max_grants,
},
diff -r 19d2922bcfb9 -r aea2b06769f3 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h Thu Oct 06 19:11:51 2011 +0100
+++ b/tools/libxc/xenctrl.h Thu Oct 06 19:28:53 2011 +0100
@@ -1349,6 +1349,29 @@
uint32_t *refs,
int prot);
+/**
+ * Memory maps a grant reference from one domain to a local address range.
+ * Mappings should be unmapped with xc_gnttab_munmap. If notify_offset or
+ * notify_port are not -1, this version 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. Logs errors.
+ *
+ * @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 prot same flag as in mmap()
+ * @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,
+ int prot,
+ 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 -r 19d2922bcfb9 -r aea2b06769f3 tools/libxc/xenctrlosdep.h
--- a/tools/libxc/xenctrlosdep.h Thu Oct 06 19:11:51 2011 +0100
+++ b/tools/libxc/xenctrlosdep.h Thu Oct 06 19:28:53 2011 +0100
@@ -105,20 +105,12 @@
int (*unmask)(xc_evtchn *xce, xc_osdep_handle h, evtchn_port_t
port);
} evtchn;
struct {
- void *(*map_grant_ref)(xc_gnttab *xcg, xc_osdep_handle h,
- uint32_t domid,
- uint32_t ref,
- int prot);
- void *(*map_grant_refs)(xc_gnttab *xcg, xc_osdep_handle h,
- uint32_t count,
- uint32_t *domids,
- uint32_t *refs,
- int prot);
- void *(*map_domain_grant_refs)(xc_gnttab *xcg, xc_osdep_handle h,
- uint32_t count,
- uint32_t domid,
- uint32_t *refs,
- int prot);
+#define XC_GRANT_MAP_SINGLE_DOMAIN 0x1
+ void *(*grant_map)(xc_gnttab *xcg, xc_osdep_handle h,
+ uint32_t count, int flags, int prot,
+ uint32_t *domids, uint32_t *refs,
+ uint32_t notify_offset,
+ evtchn_port_t notify_port);
int (*munmap)(xc_gnttab *xcg, xc_osdep_handle h,
void *start_address,
uint32_t count);
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