[Qemu-devel] [PULL 0/2] Xen 2013-10-10

[Qemu-devel] [PULL 0/2] Xen 2013-10-10

[Stefano Stabellini]

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The following changes since commit a684f3cf9b9b9c3cb82be87aafc463de8974610c:

  Merge remote-tracking branch 'kraxel/seabios-1.7.3.2' into staging (2013-09-30 17:15:27 -0500)

are available in the git repository at:

  git://xenbits.xen.org/people/sstabellini/qemu-dm.git xen-2013-10-10

Matthew Daley (1):
      xen_disk: mark ioreq as mapped before unmapping in error case

Roger Pau Monné (1):
      qemu/xen: make use of xenstore relative paths

 hw/block/xen_disk.c  |    1 +
 hw/xen/xen_backend.c |   19 ++++++-------------
 xen-all.c            |    2 +-
 3 files changed, 8 insertions(+), 14 deletions(-)

[PULL 0/2] Xen 2013-10-10

[Stefano Stabellini]

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The following changes since commit a684f3cf9b9b9c3cb82be87aafc463de8974610c:

  Merge remote-tracking branch 'kraxel/seabios-1.7.3.2' into staging (2013-09-30 17:15:27 -0500)

are available in the git repository at:

  git://xenbits.xen.org/people/sstabellini/qemu-dm.git xen-2013-10-10

Matthew Daley (1):
      xen_disk: mark ioreq as mapped before unmapping in error case

Roger Pau Monné (1):
      qemu/xen: make use of xenstore relative paths

 hw/block/xen_disk.c  |    1 +
 hw/xen/xen_backend.c |   19 ++++++-------------
 xen-all.c            |    2 +-
 3 files changed, 8 insertions(+), 14 deletions(-)

[Qemu-devel] [PULL 1/2] xen_disk: mark ioreq as mapped before unmapping in error case

[Stefano Stabellini]

From: Matthew Daley <mattjd@gmail.com>

Commit 4472beae modified the semantics of ioreq_{un,}map so that they are
idempotent if called when they're not needed (ie., twice in a row). However,
it neglected to handle the case where batch mapping is not being used (the
default), and one of the grants fails to map. In this case, ioreq_unmap will
be called to unwind and unmap any mappings already performed, but ioreq_unmap
simply returns due to the aforementioned change (the ioreq has not already
been marked as mapped).

The frontend user can therefore force xen_disk to leak grant mappings, a
per-domain limited resource.

Fix by marking the ioreq as mapped before calling ioreq_unmap in this
situation.

Signed-off-by: Matthew Daley <mattjd@gmail.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: qemu-stable@nongnu.org
---
 hw/block/xen_disk.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index f35fc59..8742294 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -405,6 +405,7 @@ static int ioreq_map(struct ioreq *ioreq)
                 xen_be_printf(&ioreq->blkdev->xendev, 0,
                               "can't map grant ref %d (%s, %d maps)\n",
                               refs[i], strerror(errno), ioreq->blkdev->cnt_map);
+                ioreq->mapped = 1;
                 ioreq_unmap(ioreq);
                 return -1;
             }
-- 
1.7.2.5

[PULL 1/2] xen_disk: mark ioreq as mapped before unmapping in error case

[Stefano Stabellini]

From: Matthew Daley <mattjd@gmail.com>

Commit 4472beae modified the semantics of ioreq_{un,}map so that they are
idempotent if called when they're not needed (ie., twice in a row). However,
it neglected to handle the case where batch mapping is not being used (the
default), and one of the grants fails to map. In this case, ioreq_unmap will
be called to unwind and unmap any mappings already performed, but ioreq_unmap
simply returns due to the aforementioned change (the ioreq has not already
been marked as mapped).

The frontend user can therefore force xen_disk to leak grant mappings, a
per-domain limited resource.

Fix by marking the ioreq as mapped before calling ioreq_unmap in this
situation.

Signed-off-by: Matthew Daley <mattjd@gmail.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: qemu-stable@nongnu.org
---
 hw/block/xen_disk.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index f35fc59..8742294 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -405,6 +405,7 @@ static int ioreq_map(struct ioreq *ioreq)
                 xen_be_printf(&ioreq->blkdev->xendev, 0,
                               "can't map grant ref %d (%s, %d maps)\n",
                               refs[i], strerror(errno), ioreq->blkdev->cnt_map);
+                ioreq->mapped = 1;
                 ioreq_unmap(ioreq);
                 return -1;
             }
-- 
1.7.2.5

[Qemu-devel] [PULL 2/2] qemu/xen: make use of xenstore relative paths

[Stefano Stabellini]

From: Roger Pau Monné <roger.pau@citrix.com>

Qemu has several hardcoded xenstore paths that are only valid on Dom0.
Attempts to launch a Qemu instance (to act as a userspace backend for
PV disks) will fail because Qemu is not able to access those paths
when running on a domain different than Dom0.

Instead make the xenstore paths relative to the domain where Qemu is
actually running.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Cc: xen-devel@lists.xenproject.org
Cc: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/xen/xen_backend.c |   19 ++++++-------------
 xen-all.c            |    2 +-
 2 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index d82ce5d..197795f 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -205,7 +205,6 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
                                            struct XenDevOps *ops)
 {
     struct XenDevice *xendev;
-    char *dom0;
 
     xendev = xen_be_find_xendev(type, dom, dev);
     if (xendev) {
@@ -219,12 +218,10 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
     xendev->dev   = dev;
     xendev->ops   = ops;
 
-    dom0 = xs_get_domain_path(xenstore, 0);
-    snprintf(xendev->be, sizeof(xendev->be), "%s/backend/%s/%d/%d",
-             dom0, xendev->type, xendev->dom, xendev->dev);
+    snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
+             xendev->type, xendev->dom, xendev->dev);
     snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
              xendev->type, xendev->dev);
-    free(dom0);
 
     xendev->debug      = debug;
     xendev->local_port = -1;
@@ -570,14 +567,12 @@ static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
 {
     struct XenDevice *xendev;
     char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
-    char **dev = NULL, *dom0;
+    char **dev = NULL;
     unsigned int cdev, j;
 
     /* setup watch */
-    dom0 = xs_get_domain_path(xenstore, 0);
     snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
-    snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
-    free(dom0);
+    snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
     if (!xs_watch(xenstore, path, token)) {
         xen_be_printf(NULL, 0, "xen be: watching backend path (%s) failed\n", path);
         return -1;
@@ -603,12 +598,10 @@ static void xenstore_update_be(char *watch, char *type, int dom,
                                struct XenDevOps *ops)
 {
     struct XenDevice *xendev;
-    char path[XEN_BUFSIZE], *dom0, *bepath;
+    char path[XEN_BUFSIZE], *bepath;
     unsigned int len, dev;
 
-    dom0 = xs_get_domain_path(xenstore, 0);
-    len = snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
-    free(dom0);
+    len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
     if (strncmp(path, watch, len) != 0) {
         return;
     }
diff --git a/xen-all.c b/xen-all.c
index 48e881b..9a27899 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -949,7 +949,7 @@ static void xenstore_record_dm_state(struct xs_handle *xs, const char *state)
         exit(1);
     }
 
-    snprintf(path, sizeof (path), "/local/domain/0/device-model/%u/state", xen_domid);
+    snprintf(path, sizeof (path), "device-model/%u/state", xen_domid);
     if (!xs_write(xs, XBT_NULL, path, state, strlen(state))) {
         fprintf(stderr, "error recording dm state\n");
         exit(1);
-- 
1.7.2.5

[PULL 2/2] qemu/xen: make use of xenstore relative paths

[Stefano Stabellini]

From: Roger Pau Monné <roger.pau@citrix.com>

Qemu has several hardcoded xenstore paths that are only valid on Dom0.
Attempts to launch a Qemu instance (to act as a userspace backend for
PV disks) will fail because Qemu is not able to access those paths
when running on a domain different than Dom0.

Instead make the xenstore paths relative to the domain where Qemu is
actually running.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Cc: xen-devel@lists.xenproject.org
Cc: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/xen/xen_backend.c |   19 ++++++-------------
 xen-all.c            |    2 +-
 2 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index d82ce5d..197795f 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -205,7 +205,6 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
                                            struct XenDevOps *ops)
 {
     struct XenDevice *xendev;
-    char *dom0;
 
     xendev = xen_be_find_xendev(type, dom, dev);
     if (xendev) {
@@ -219,12 +218,10 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
     xendev->dev   = dev;
     xendev->ops   = ops;
 
-    dom0 = xs_get_domain_path(xenstore, 0);
-    snprintf(xendev->be, sizeof(xendev->be), "%s/backend/%s/%d/%d",
-             dom0, xendev->type, xendev->dom, xendev->dev);
+    snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
+             xendev->type, xendev->dom, xendev->dev);
     snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
              xendev->type, xendev->dev);
-    free(dom0);
 
     xendev->debug      = debug;
     xendev->local_port = -1;
@@ -570,14 +567,12 @@ static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
 {
     struct XenDevice *xendev;
     char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
-    char **dev = NULL, *dom0;
+    char **dev = NULL;
     unsigned int cdev, j;
 
     /* setup watch */
-    dom0 = xs_get_domain_path(xenstore, 0);
     snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
-    snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
-    free(dom0);
+    snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
     if (!xs_watch(xenstore, path, token)) {
         xen_be_printf(NULL, 0, "xen be: watching backend path (%s) failed\n", path);
         return -1;
@@ -603,12 +598,10 @@ static void xenstore_update_be(char *watch, char *type, int dom,
                                struct XenDevOps *ops)
 {
     struct XenDevice *xendev;
-    char path[XEN_BUFSIZE], *dom0, *bepath;
+    char path[XEN_BUFSIZE], *bepath;
     unsigned int len, dev;
 
-    dom0 = xs_get_domain_path(xenstore, 0);
-    len = snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
-    free(dom0);
+    len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
     if (strncmp(path, watch, len) != 0) {
         return;
     }
diff --git a/xen-all.c b/xen-all.c
index 48e881b..9a27899 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -949,7 +949,7 @@ static void xenstore_record_dm_state(struct xs_handle *xs, const char *state)
         exit(1);
     }
 
-    snprintf(path, sizeof (path), "/local/domain/0/device-model/%u/state", xen_domid);
+    snprintf(path, sizeof (path), "device-model/%u/state", xen_domid);
     if (!xs_write(xs, XBT_NULL, path, state, strlen(state))) {
         fprintf(stderr, "error recording dm state\n");
         exit(1);
-- 
1.7.2.5