Re: [Qemu-devel] [PATCH V6 02/15] xen: Support new libxc calls from xen unstable.

[Alexander Graf <agraf@suse.de>]

On 21.10.2010, at 19:36, Anthony.Perard@citrix.com wrote:

> From: Anthony PERARD <anthony.perard@citrix.com>
> 
> Update the libxenctrl calls in Qemu to use the new interface, otherwise
> Qemu wouldn't be able to build against new versions of the library.
> 
> We also check libxenctrl version in configure, from Xen 3.3.0 to Xen
> unstable.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
> configure            |   67 ++++++++++++++++++++++++++++++++++++++++++++++++-
> hw/xen_backend.c     |   10 +++---
> hw/xen_backend.h     |    2 +-
> hw/xen_common.h      |   38 +++++++++++++++++-----------
> hw/xen_disk.c        |   12 ++++----
> hw/xen_domainbuild.c |    2 +-
> hw/xen_nic.c         |   16 ++++++------
> 7 files changed, 109 insertions(+), 38 deletions(-)
> 
> diff --git a/configure b/configure
> index 9ed05de..f6a7073 100755
> --- a/configure
> +++ b/configure
> @@ -284,6 +284,7 @@ vnc_jpeg=""
> vnc_png=""
> vnc_thread="no"
> xen=""
> +xen_ctrl_version=""
> linux_aio=""
> attr=""
> vhost_net=""
> @@ -1135,20 +1136,81 @@ fi
> 
> if test "$xen" != "no" ; then
>   xen_libs="-lxenstore -lxenctrl -lxenguest"
> +
> +  # Xen unstable
>   cat > $TMPC <<EOF
> #include <xenctrl.h>
> #include <xs.h>
> -int main(void) { xs_daemon_open(); xc_interface_open(); return 0; }
> +#include <stdint.h>
> +#include <xen/hvm/hvm_info_table.h>
> +#if !defined(HVM_MAX_VCPUS)
> +# error HVM_MAX_VCPUS not defined
> +#endif
> +int main(void) {
> +  xc_interface *xc;
> +  xs_daemon_open();
> +  xc_interface_open(0, 0, 0);
> +  xc_hvm_set_mem_type(0, 0, HVMMEM_ram_ro, 0, 0);
> +  xc_gnttab_open(xc);
> +  return 0;
> +}
> EOF
>   if compile_prog "" "$xen_libs" ; then
> +    xen_ctrl_version=410
>     xen=yes
> -    libs_softmmu="$xen_libs $libs_softmmu"
> +
> +  # Xen 4.0.0
> +  elif (
> +      cat > $TMPC <<EOF
> +#include <xenctrl.h>
> +#include <xs.h>
> +#include <stdint.h>
> +#include <xen/hvm/hvm_info_table.h>
> +#if !defined(HVM_MAX_VCPUS)
> +# error HVM_MAX_VCPUS not defined
> +#endif
> +int main(void) {
> +  xs_daemon_open();
> +  xc_interface_open();
> +  xc_gnttab_open();
> +  xc_hvm_set_mem_type(0, 0, HVMMEM_ram_ro, 0, 0);
> +  return 0;
> +}
> +EOF
> +      compile_prog "" "$xen_libs"
> +    ) ; then
> +    xen_ctrl_version=400
> +    xen=yes
> +
> +  # Xen 3.3.0, 3.4.0
> +  elif (
> +      cat > $TMPC <<EOF
> +#include <xenctrl.h>
> +#include <xs.h>
> +int main(void) {
> +  xs_daemon_open();
> +  xc_interface_open();
> +  xc_gnttab_open();
> +  xc_hvm_set_mem_type(0, 0, HVMMEM_ram_ro, 0, 0);
> +  return 0;
> +}
> +EOF
> +      compile_prog "" "$xen_libs"
> +    ) ; then
> +    xen_ctrl_version=330
> +    xen=yes
> +
> +  # Xen not found or unsupported
>   else
>     if test "$xen" = "yes" ; then
>       feature_not_found "xen"
>     fi
>     xen=no
>   fi
> +
> +  if test "$xen" = "yes"; then
> +    libs_softmmu="$xen_libs $libs_softmmu"
> +  fi
> fi
> 
> ##########################################
> @@ -2546,6 +2608,7 @@ if test "$bluez" = "yes" ; then
> fi
> if test "$xen" = "yes" ; then
>   echo "CONFIG_XEN=y" >> $config_host_mak
> +  echo "CONFIG_XEN_CTRL_INTERFACE_VERSION=$xen_ctrl_version" >> $config_host_mak
> fi
> if test "$io_thread" = "yes" ; then
>   echo "CONFIG_IOTHREAD=y" >> $config_host_mak
> diff --git a/hw/xen_backend.c b/hw/xen_backend.c
> index 860b038..3e99751 100644
> --- a/hw/xen_backend.c
> +++ b/hw/xen_backend.c
> @@ -43,7 +43,7 @@
> /* ------------------------------------------------------------- */
> 
> /* public */
> -int xen_xc;
> +qemu_xc_interface xen_xc = XC_HANDLER_INITIAL_VALUE;
> struct xs_handle *xenstore = NULL;
> const char *xen_protocol;
> 
> @@ -216,7 +216,7 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
>     fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> 
>     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
> -        xendev->gnttabdev = xc_gnttab_open();
> +        xendev->gnttabdev = xc_gnttab_open(xen_xc);
>         if (xendev->gnttabdev < 0) {
>             xen_be_printf(NULL, 0, "can't open gnttab device\n");
>             xc_evtchn_close(xendev->evtchndev);
> @@ -269,7 +269,7 @@ static struct XenDevice *xen_be_del_xendev(int dom, int dev)
>         if (xendev->evtchndev >= 0)
>             xc_evtchn_close(xendev->evtchndev);
>         if (xendev->gnttabdev >= 0)
> -            xc_gnttab_close(xendev->gnttabdev);
> +            xc_gnttab_close(xen_xc, xendev->gnttabdev);
> 
>         QTAILQ_REMOVE(&xendevs, xendev, next);
>         qemu_free(xendev);
> @@ -627,8 +627,8 @@ int xen_be_init(void)
>     if (qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL) < 0)
>         goto err;
> 
> -    xen_xc = xc_interface_open();
> -    if (xen_xc == -1) {
> +    xen_xc = xc_interface_open(NULL, NULL, 0);
> +    if (xen_xc == XC_HANDLER_INITIAL_VALUE) {
>         xen_be_printf(NULL, 0, "can't open xen interface\n");
>         goto err;
>     }
> diff --git a/hw/xen_backend.h b/hw/xen_backend.h
> index 1b428e3..7d84098 100644
> --- a/hw/xen_backend.h
> +++ b/hw/xen_backend.h
> @@ -55,7 +55,7 @@ struct XenDevice {
> /* ------------------------------------------------------------- */
> 
> /* variables */
> -extern int xen_xc;
> +extern qemu_xc_interface xen_xc;
> extern struct xs_handle *xenstore;
> extern const char *xen_protocol;
> 
> diff --git a/hw/xen_common.h b/hw/xen_common.h
> index 8a55b44..9f75e52 100644
> --- a/hw/xen_common.h
> +++ b/hw/xen_common.h
> @@ -1,6 +1,8 @@
> #ifndef QEMU_HW_XEN_COMMON_H
> #define QEMU_HW_XEN_COMMON_H 1
> 
> +#include "config-host.h"
> +
> #include <stddef.h>
> #include <inttypes.h>
> 
> @@ -13,22 +15,28 @@
> #include "qemu-queue.h"
> 
> /*
> - * tweaks needed to build with different xen versions
> - *  0x00030205 -> 3.1.0
> - *  0x00030207 -> 3.2.0
> - *  0x00030208 -> unstable
> + * We don't support Xen prior to 3.3.0.
>  */
> -#include <xen/xen-compat.h>
> -#if __XEN_LATEST_INTERFACE_VERSION__ < 0x00030205
> -# define evtchn_port_or_error_t int
> -#endif
> -#if __XEN_LATEST_INTERFACE_VERSION__ < 0x00030207
> -# define xc_map_foreign_pages xc_map_foreign_batch
> -#endif
> -#if __XEN_LATEST_INTERFACE_VERSION__ < 0x00030208
> -# define xen_mb()  mb()
> -# define xen_rmb() rmb()
> -# define xen_wmb() wmb()
> +
> +/* Xen unstable */
> +#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 410
> +typedef int qemu_xc_interface;
> +#  define XC_HANDLER_INITIAL_VALUE               -1
> +#  define xc_fd(xen_xc)                          xen_xc
> +#  define xc_interface_open(l, dl, f)            xc_interface_open()
> +#  define xc_gnttab_open(xc)                     xc_gnttab_open()
> +#  define xc_gnttab_map_grant_ref(xc, gnt, domid, ref, flags) \
> +    xc_gnttab_map_grant_ref(gnt, domid, ref, flags)
> +#  define xc_gnttab_map_grant_refs(xc, gnt, count, domids, refs, flags) \
> +    xc_gnttab_map_grant_refs(gnt, count, domids, refs, flags)
> +#  define xc_gnttab_munmap(xc, gnt, pages, niov) xc_gnttab_munmap(gnt, pages, niov)
> +#  define xc_gnttab_close(xc, dev)               xc_gnttab_close(dev)

All these defines are very icky. In my patchset I replace all those libxc calls by indirect calls through a struct anyways. Maybe it'd make sense to integrate that part into your series already.

That way you could make this whole compat stuff a lot cleaner. You could use static inline functions to create wrappers to the real calls and just assign those as callbacks in the dispatch struct.

In general, I'd disagree to the preprocessor approach here. If you're not going with the libxc dispatch struct patch, I'd at least like to see all those converted to static inline functions called with different names internally.


Alex