x86/shadow: restrict OOS allocation to when it's really needed

PV domains won't use it, and even HVM ones won't when OOS is turned off
for them. There's therefore no point in putting extra pressure on the
(limited) pool of memory.

While there also zap the sh_type_to_size[] entry when OOS is disabled
altogether.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>

diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index e522267325cd998fb4dda2014719ce980ff648db..a0ae6adb4f4865a60ae2d753e85002d501823634 100644 (file)
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -61,7 +61,9 @@ const uint8_t sh_type_to_size[] = {
     [SH_type_l4_64_shadow]   = 1,
     [SH_type_p2m_table]      = 1,
     [SH_type_monitor_table]  = 1,
+#if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
     [SH_type_oos_snapshot]   = 1,
+#endif
 };
 #endif /* CONFIG_HVM */
 
@@ -2341,7 +2343,8 @@ static void sh_update_paging_modes(struct vcpu *v)
 #endif /* (SHADOW_OPTIMIZATIONS & SHOPT_VIRTUAL_TLB) */
 
 #if (SHADOW_OPTIMIZATIONS & SHOPT_OUT_OF_SYNC)
-    if ( mfn_eq(v->arch.paging.shadow.oos_snapshot[0], INVALID_MFN) )
+    if ( !(d->options & XEN_DOMCTL_CDF_oos_off) &&
+         mfn_eq(v->arch.paging.shadow.oos_snapshot[0], INVALID_MFN) )
     {
         int i;