[src/trunk]: src/sys/arch/xen/i386 Apply patch from Jed Davis, posted to port...

[bouyer <bouyer%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c32772be76b2
branches:  trunk
changeset: 584164:c32772be76b2
user:      bouyer <bouyer%NetBSD.org@localhost>
date:      Sat Sep 10 15:46:04 2005 +0000

description:
Apply patch from Jed Davis, posted to port-xen:
In pmap_remap_pages() new mappings are created (PG_RW|PG_M). When saving
a domain, the hypervisor will refuse to map the foreing pages RW.
As a temporary measure, retry the mapping read-only if PG_RW fails, so that
domain save will work. Also fix the PTP's wire_count if the MMU update
fails (prevent a kernel panic).

diffstat:

 sys/arch/xen/i386/pmap.c |  35 ++++++++++++++++++++++++++++++-----
 1 files changed, 30 insertions(+), 5 deletions(-)

diffs (69 lines):

diff -r 9d6981224b72 -r c32772be76b2 sys/arch/xen/i386/pmap.c
--- a/sys/arch/xen/i386/pmap.c  Sat Sep 10 15:41:54 2005 +0000
+++ b/sys/arch/xen/i386/pmap.c  Sat Sep 10 15:46:04 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.12 2005/05/29 15:57:02 chs Exp $    */
+/*     $NetBSD: pmap.c,v 1.13 2005/09/10 15:46:04 bouyer Exp $ */
 /*     NetBSD: pmap.c,v 1.179 2004/10/10 09:55:24 yamt Exp             */
 
 /*
@@ -61,7 +61,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.12 2005/05/29 15:57:02 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.13 2005/09/10 15:46:04 bouyer Exp $");
 
 #include "opt_cputype.h"
 #include "opt_user_ldt.h"
@@ -4064,7 +4064,9 @@
        struct vm_page_md *mdpg;
        struct pv_head *old_pvh;
        struct pv_entry *pve = NULL; /* XXX gcc */
-       int error;
+       int error, dptpwire;
+
+       dptpwire = 0;
 
        XENPRINTK(("pmap_remap_pages(%p, %p, %p, %d, %08x, %d)\n",
            pmap, (void *)va, (void *)pa, npages, flags, dom));
@@ -4230,14 +4232,37 @@
        } else {
                pmap->pm_stats.resident_count++;
                pmap->pm_stats.wired_count++;
-               if (ptp)
+               if (ptp) {
+                       dptpwire = 1;
                        ptp->wire_count++;
+               }
        }
 
        //printf("pmap initial setup");
        maptp = (pt_entry_t *)vtomach((vaddr_t)&ptes[x86_btop(va)]);
+ change_pte:
        error = xpq_update_foreign(maptp, npte, dom);
-
+       if (error) {
+               if (npte & PG_RW) {
+                       /* 
+                        * XXXjld%panix.com@localhost: Some things cannot be
+                        * mapped read/write, even by a privileged
+                        * domain.  This wouldn't be necessary if
+                        * pmap_remap_pages had a "prot" parameter
+                        * like pmap_enter does.
+                        */
+                       npte &= ~(PG_RW | PG_M);
+                       //printf("pmap_remap_pages: losing write bit npte=%lx\n", (unsigned long)npte);
+                       goto change_pte;
+               }
+               printf("pmap_remap_pages: xpq_update_foreign failed va=%lx"
+                   " npte=%lx error=%d dptpwire=%d\n",
+                   va, (unsigned long)npte, error, dptpwire);
+               ptp->wire_count -= dptpwire;
+               /* XXX fix other stats? */
+               goto out;
+       }
+       
 shootdown_test:
        /* Update page attributes if needed */
        if ((opte & (PG_V | PG_U)) == (PG_V | PG_U)) {