[PATCH v2 1/6] x86/pv: fix emulation of wb{,no}invd to flush all pCPU caches

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

The current emulation of wb{,no}invd is bogus for PV guests: it will only
flush the current pCPU cache, without taking into account pCPUs where the
vCPU had run previously.  Resort to flushing the cache on all host pCPUs to
make it correct.

Fixes: 799fed0a7cc5 ("Priv-op emulation in Xen, for RDMSR/WRMSR/WBINVD")
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v1:
 - Use the recently introduced FLUSH_CACHE_WRITEBACK.
---
 xen/arch/x86/pv/emul-priv-op.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c
index 295d847ea24c..20a90703c83c 100644
--- a/xen/arch/x86/pv/emul-priv-op.c
+++ b/xen/arch/x86/pv/emul-priv-op.c
@@ -1198,13 +1198,13 @@ static int cf_check cache_op(
     if ( !cache_flush_permitted(current->domain) )
         /*
          * Non-physdev domain attempted WBINVD; ignore for now since
-         * newer linux uses this in some start-of-day timing loops.
+         * Linux uses this in some start-of-day code.
          */
         ;
     else if ( op == x86emul_wbnoinvd /* && cpu_has_wbnoinvd */ )
-        wbnoinvd();
+        flush_all(FLUSH_CACHE_WRITEBACK);
     else
-        wbinvd();
+        flush_all(FLUSH_CACHE);
 
     return X86EMUL_OKAY;
 }
-- 
2.48.1