[Xen-devel] [PATCH] domain_create: honour global grant/maptrack frame limits...

[Paul Durrant <pdurrant@xxxxxxxxxx>]

...when their values are larger than the per-domain configured limits.

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Julien Grall <julien@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Wei Liu <wl@xxxxxxx>

After mining through commits it is still unclear to me exactly when Xen
stopped honouring the global values, but I really think this commit should
be back-ported to stable trees as it was a behavioural change that can
cause domUs to fail in non-obvious ways.
---
 xen/common/domain.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 611116c7fc..aad6d55b82 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -335,6 +335,7 @@ struct domain *domain_create(domid_t domid,
     enum { INIT_watchdog = 1u<<1,
            INIT_evtchn = 1u<<3, INIT_gnttab = 1u<<4, INIT_arch = 1u<<5 };
     int err, init_status = 0;
+    unsigned int max_grant_frames, max_maptrack_frames;
 
     if ( config && (err = sanitise_domain_config(config)) )
         return ERR_PTR(err);
@@ -456,8 +457,17 @@ struct domain *domain_create(domid_t domid,
             goto fail;
         init_status |= INIT_evtchn;
 
-        if ( (err = grant_table_init(d, config->max_grant_frames,
-                                     config->max_maptrack_frames)) != 0 )
+        /*
+         * Make sure that the configured values don't reduce any
+         * global command line override.
+         */
+        max_grant_frames = max(config->max_grant_frames,
+                               opt_max_grant_frames);
+        max_maptrack_frames = max(config->max_maptrack_frames,
+                                  opt_max_maptrack_frames);
+
+        if ( (err = grant_table_init(d, max_grant_frames,
+                                     max_maptrack_frames)) != 0 )
             goto fail;
         init_status |= INIT_gnttab;
 
-- 
2.17.1


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