[v3] x86: assorted shadow mode adjustments

[PATCH v3 06/12] x86/shadow: restrict OOS allocation to when it's really needed

Posted by Jan Beulich 2 years, 8 months ago

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>
---
v3: New.

--- 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 */
 
@@ -1771,7 +1773,8 @@ static void sh_update_paging_modes(struc
 #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;

Re: [PATCH v3 06/12] x86/shadow: restrict OOS allocation to when it's really needed

Posted by Roger Pau Monné 2 years, 8 months ago

On Tue, May 16, 2023 at 09:40:22AM +0200, Jan Beulich wrote:
> 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>

Thanks, Roger.