Re: [Qemu-devel] [PATCH QEMU-XEN v4 2/9] xen: Switch to libxenevtchn interface for compat shims.

[Stefano Stabellini]

On Wed, 21 Oct 2015, Ian Campbell wrote:
> In Xen 4.7 we are refactoring parts libxenctrl into a number of
> separate libraries which will provide backward and forward API and ABI
> compatiblity.
> 
> One such library will be libxenevtchn which provides access to event
> channels.
> 
> In preparation for this switch the compatibility layer in xen_common.h
> (which support building with older versions of Xen) to use what will
> be the new library API. This means that the evtchn shim will disappear
> for versions of Xen which include libxenevtchn.
> 
> To simplify things for the <= 4.0.0 support we wrap the int fd in a
> malloc(sizeof int) such that the handle is always a pointer. This
> leads to less typedef headaches and the need for
> XC_HANDLER_INITIAL_VALUE etc for these interfaces.
> 
> Build tested with 4.0 and 4.5.
> 
> Note that this patch does not add any support for actually using
> libxenevtchn, it just adjusts the existing shims.
> 
> Note that xc_evtchn_alloc_unbound functionality remains in libxenctrl,
> since that functionality is not exposed by /dev/xen/evtchn.
> 
> Signed-off-by: Ian Campbell 

Reviewed-by: Stefano Stabellini 


> v4: Ran checkpatch, fixed all errors
> Allocate correct size for handle (i.e. not size of the ptr)
> ---
>  hw/xen/xen_backend.c | 31 ---
>  include/hw/xen/xen_backend.h |  2 +-
>  include/hw/xen/xen_common.h  | 44 
> ++--
>  xen-hvm.c| 25 +
>  4 files changed, 64 insertions(+), 38 deletions(-)
> 
> diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
> index b2cb22b..342ec9b 100644
> --- a/hw/xen/xen_backend.c
> +++ b/hw/xen/xen_backend.c
> @@ -243,19 +243,19 @@ static struct XenDevice *xen_be_get_xendev(const char 
> *type, int dom, int dev,
>  xendev->debug  = debug;
>  xendev->local_port = -1;
>  
> -xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
> -if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
> +xendev->evtchndev = xenevtchn_open(NULL, 0);
> +if (xendev->evtchndev == NULL) {
>  xen_be_printf(NULL, 0, "can't open evtchn device\n");
>  g_free(xendev);
>  return NULL;
>  }
> -fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> +fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
>  
>  if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
>  xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
>  if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
>  xen_be_printf(NULL, 0, "can't open gnttab device\n");
> -xc_evtchn_close(xendev->evtchndev);
> +xenevtchn_close(xendev->evtchndev);
>  g_free(xendev);
>  return NULL;
>  }
> @@ -306,8 +306,8 @@ static struct XenDevice *xen_be_del_xendev(int dom, int 
> dev)
>  g_free(xendev->fe);
>  }
>  
> -if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
> -xc_evtchn_close(xendev->evtchndev);
> +if (xendev->evtchndev != NULL) {
> +xenevtchn_close(xendev->evtchndev);
>  }
>  if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
>  xc_gnttab_close(xendev->gnttabdev);
> @@ -691,13 +691,14 @@ static void xen_be_evtchn_event(void *opaque)
>  struct XenDevice *xendev = opaque;
>  evtchn_port_t port;
>  
> -port = xc_evtchn_pending(xendev->evtchndev);
> +port = xenevtchn_pending(xendev->evtchndev);
>  if (port != xendev->local_port) {
> -xen_be_printf(xendev, 0, "xc_evtchn_pending returned %d (expected 
> %d)\n",
> +xen_be_printf(xendev, 0,
> +  "xenevtchn_pending returned %d (expected %d)\n",
>port, xendev->local_port);
>  return;
>  }
> -xc_evtchn_unmask(xendev->evtchndev, port);
> +xenevtchn_unmask(xendev->evtchndev, port);
>  
>  if (xendev->ops->event) {
>  xendev->ops->event(xendev);
> @@ -742,14 +743,14 @@ int xen_be_bind_evtchn(struct XenDevice *xendev)
>  if (xendev->local_port != -1) {
>  return 0;
>  }
> -xendev->local_port = xc_evtchn_bind_interdomain
> +xendev->local_port = xenevtchn_bind_interdomain
>  (xendev->evtchndev, xendev->dom, xendev->remote_port);
>  if (xendev->local_port == -1) {
> -xen_be_printf(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
> +xen_be_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
>  return -1;
>  }
>  xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
> -qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev),
> +qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
>  xen_be_evtchn_event, NULL, xendev);
>  return 0;
>  }
> @@ -759,15 +760,15 @@ void xen_be_unbind_evtchn(struct XenDevice *xendev)
>  if 

[Qemu-devel] [PATCH QEMU-XEN v4 2/9] xen: Switch to libxenevtchn interface for compat shims.

[Ian Campbell]

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxenevtchn which provides access to event
channels.

In preparation for this switch the compatibility layer in xen_common.h
(which support building with older versions of Xen) to use what will
be the new library API. This means that the evtchn shim will disappear
for versions of Xen which include libxenevtchn.

To simplify things for the <= 4.0.0 support we wrap the int fd in a
malloc(sizeof int) such that the handle is always a pointer. This
leads to less typedef headaches and the need for
XC_HANDLER_INITIAL_VALUE etc for these interfaces.

Build tested with 4.0 and 4.5.

Note that this patch does not add any support for actually using
libxenevtchn, it just adjusts the existing shims.

Note that xc_evtchn_alloc_unbound functionality remains in libxenctrl,
since that functionality is not exposed by /dev/xen/evtchn.

Signed-off-by: Ian Campbell 
---
v4: Ran checkpatch, fixed all errors
Allocate correct size for handle (i.e. not size of the ptr)
---
 hw/xen/xen_backend.c | 31 ---
 include/hw/xen/xen_backend.h |  2 +-
 include/hw/xen/xen_common.h  | 44 ++--
 xen-hvm.c| 25 +
 4 files changed, 64 insertions(+), 38 deletions(-)

diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index b2cb22b..342ec9b 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -243,19 +243,19 @@ static struct XenDevice *xen_be_get_xendev(const char 
*type, int dom, int dev,
 xendev->debug  = debug;
 xendev->local_port = -1;
 
-xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
-if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
+xendev->evtchndev = xenevtchn_open(NULL, 0);
+if (xendev->evtchndev == NULL) {
 xen_be_printf(NULL, 0, "can't open evtchn device\n");
 g_free(xendev);
 return NULL;
 }
-fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
+fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 
 if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
 xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
 if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
 xen_be_printf(NULL, 0, "can't open gnttab device\n");
-xc_evtchn_close(xendev->evtchndev);
+xenevtchn_close(xendev->evtchndev);
 g_free(xendev);
 return NULL;
 }
@@ -306,8 +306,8 @@ static struct XenDevice *xen_be_del_xendev(int dom, int dev)
 g_free(xendev->fe);
 }
 
-if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
-xc_evtchn_close(xendev->evtchndev);
+if (xendev->evtchndev != NULL) {
+xenevtchn_close(xendev->evtchndev);
 }
 if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
 xc_gnttab_close(xendev->gnttabdev);
@@ -691,13 +691,14 @@ static void xen_be_evtchn_event(void *opaque)
 struct XenDevice *xendev = opaque;
 evtchn_port_t port;
 
-port = xc_evtchn_pending(xendev->evtchndev);
+port = xenevtchn_pending(xendev->evtchndev);
 if (port != xendev->local_port) {
-xen_be_printf(xendev, 0, "xc_evtchn_pending returned %d (expected 
%d)\n",
+xen_be_printf(xendev, 0,
+  "xenevtchn_pending returned %d (expected %d)\n",
   port, xendev->local_port);
 return;
 }
-xc_evtchn_unmask(xendev->evtchndev, port);
+xenevtchn_unmask(xendev->evtchndev, port);
 
 if (xendev->ops->event) {
 xendev->ops->event(xendev);
@@ -742,14 +743,14 @@ int xen_be_bind_evtchn(struct XenDevice *xendev)
 if (xendev->local_port != -1) {
 return 0;
 }
-xendev->local_port = xc_evtchn_bind_interdomain
+xendev->local_port = xenevtchn_bind_interdomain
 (xendev->evtchndev, xendev->dom, xendev->remote_port);
 if (xendev->local_port == -1) {
-xen_be_printf(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
+xen_be_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
 return -1;
 }
 xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
-qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev),
+qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
 xen_be_evtchn_event, NULL, xendev);
 return 0;
 }
@@ -759,15 +760,15 @@ void xen_be_unbind_evtchn(struct XenDevice *xendev)
 if (xendev->local_port == -1) {
 return;
 }
-qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
-xc_evtchn_unbind(xendev->evtchndev, xendev->local_port);
+qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
+xenevtchn_unbind(xendev->evtchndev, xendev->local_port);