Jan Beulich
2012-May-14 10:18 UTC
[PATCH, resend] libxc: implement gnttab.set_max_grants for Linux
Legacy (non-pvops) gntdev drivers may require this operation to be
performed when the number of grants intended to be used simultaneously
exceeds a certain driver specific default limit, and qemu''s qdisk
driver is an example of needing to do so.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -541,6 +541,27 @@ static int linux_gnttab_close(xc_gnttab
return close(fd);
}
+static int linux_gnttab_set_max_grants(xc_gnttab *xch, xc_osdep_handle h,
+ uint32_t count)
+{
+ int fd = (int)h, rc;
+ struct ioctl_gntdev_set_max_grants max_grants = { .count = count };
+
+ rc = ioctl(fd, IOCTL_GNTDEV_SET_MAX_GRANTS, &max_grants);
+ if (rc) {
+ /*
+ * Newer (e.g. pv-ops) kernels don''t implement this IOCTL,
+ * so ignore the resulting specific failure.
+ */
+ if (errno == ENOTTY)
+ rc = 0;
+ else
+ PERROR("linux_gnttab_set_max_grants: ioctl SET_MAX_GRANTS
failed");
+ }
+
+ return rc;
+}
+
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,
@@ -680,6 +701,7 @@ static struct xc_osdep_ops linux_gnttab_
.close = &linux_gnttab_close,
.u.gnttab = {
+ .set_max_grants = linux_gnttab_set_max_grants,
.grant_map = &linux_gnttab_grant_map,
.munmap = &linux_gnttab_munmap,
},
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Ian Jackson
2012-May-14 15:20 UTC
Re: [PATCH, resend] libxc: implement gnttab.set_max_grants for Linux
Jan Beulich writes ("[Xen-devel] [PATCH, resend] libxc: implement
gnttab.set_max_grants for Linux"):> Legacy (non-pvops) gntdev drivers may require this operation to be
> performed when the number of grants intended to be used simultaneously
> exceeds a certain driver specific default limit, and qemu''s qdisk
> driver is an example of needing to do so.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>