WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: [PATCH 3 of 4] Nested p2m: clarify logic in p2m_get_nest

To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH 3 of 4] Nested p2m: clarify logic in p2m_get_nestedp2m()
From: Christoph Egger <Christoph.Egger@xxxxxxx>
Date: Fri, 24 Jun 2011 16:25:40 +0200
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Fri, 24 Jun 2011 07:29:16 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <b265371addbbc8a58c95.1308759029@xxxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <patchbomb.1308759026@xxxxxxxxxxxxxxxxxxxxxxx> <b265371addbbc8a58c95.1308759029@xxxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; NetBSD amd64; en-US; rv:1.9.2.17) Gecko/20110523 Lightning/1.0b3pre Thunderbird/3.1.10
On 06/22/11 18:10, Tim Deegan wrote:
# HG changeset patch
# User Tim Deegan<Tim.Deegan@xxxxxxxxxx>
# Date 1308758648 -3600
# Node ID b265371addbbc8a58c95a269fe3cd0fdc866aaa3
# Parent  dcb8ae5e3eaf6516c889087dfb15efa41a1ac3e9
Nested p2m: clarify logic in p2m_get_nestedp2m()

This just makes the behaviour of this function a bit more explicit.  It
may be that it also needs to be changed. :)

Signed-off-by: Tim Deegan<Tim.Deegan@xxxxxxxxxx>

diff -r dcb8ae5e3eaf -r b265371addbb xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c     Wed Jun 22 17:04:08 2011 +0100
+++ b/xen/arch/x86/mm/p2m.c     Wed Jun 22 17:04:08 2011 +0100
@@ -1131,11 +1131,9 @@ p2m_get_nestedp2m(struct vcpu *v, uint64

      d = v->domain;
      nestedp2m_lock(d);
-    for (i = 0; i<  MAX_NESTEDP2M; i++) {
-        p2m = d->arch.nested_p2m[i];
-        if ((p2m->cr3 != cr3&&  p2m->cr3 != CR3_EADDR) || (p2m != nv->nv_p2m))
-            continue;
-
+    p2m = nv->nv_p2m;
+    if ( p2m&&  (p2m->cr3 == cr3 || p2m->cr3 == CR3_EADDR) )
+    {
          nv->nv_flushp2m = 0;
          p2m_getlru_nestedp2m(d, p2m);
          nv->nv_p2m = p2m;



Ok, thanks.

In p2m_get_nestedp2m() replace this code hunk

    for (i = 0; i < MAX_NESTEDP2M; i++) {
        p2m = p2m_getlru_nestedp2m(d, NULL);
        p2m_flush_locked(p2m);
    }

with

    p2m = p2m_getlru_nestedp2m(d, NULL);
    p2m_flush_locked(p2m);

The 'i'' variable is unused then. This fixes an endless loop of
nested page faults I observe with SMP l2 guests.

The nested page fault loop happens in conjunction with the change
in patch 4 in nestedhap_fix_p2m().

Christoph


--
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Einsteinring 24, 85689 Dornach b. Muenchen
Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>