# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxxx
# Date 1169072876 0
# Node ID e5f585514b1696a1e3be5047f39ba5d4eacaa618
# Parent 05c1db1b8cb9a6bf7371ed75895b19c3baefd3ec
[XEN] Simplify CR3 switching code (remove slow path that allows old
page tables to be writable in new page tables -- shadow mode cannot
handle the failure case and it is easy to work around this in the
guest anyway). Also remove broken shadow-refcount compat-mode case.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
xen/arch/x86/mm.c | 63 +++++++++++-------------------------------------------
1 files changed, 13 insertions(+), 50 deletions(-)
diff -r 05c1db1b8cb9 -r e5f585514b16 xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Wed Jan 17 21:07:43 2007 +0000
+++ b/xen/arch/x86/mm.c Wed Jan 17 22:27:56 2007 +0000
@@ -1768,25 +1768,14 @@ int new_guest_cr3(unsigned long mfn)
int okay;
unsigned long old_base_mfn;
- if ( is_hvm_domain(d) && !hvm_paging_enabled(v) )
- return 0;
-
#ifdef CONFIG_COMPAT
if ( IS_COMPAT(d) )
{
- l4_pgentry_t l4e = l4e_from_pfn(
- mfn, _PAGE_PRESENT|_PAGE_RW|_PAGE_USER|_PAGE_ACCESSED);
-
- if ( shadow_mode_refcounts(d) )
- {
- okay = get_page_from_pagenr(mfn, d);
- old_base_mfn = l4e_get_pfn(l4e);
- if ( okay && old_base_mfn )
- put_page(mfn_to_page(old_base_mfn));
- }
- else
- okay = mod_l4_entry(__va(pagetable_get_paddr(v->arch.guest_table)),
- l4e, 0);
+ okay = shadow_mode_refcounts(d)
+ ? 0 /* Old code was broken, but what should it be? */
+ : mod_l4_entry(__va(pagetable_get_paddr(v->arch.guest_table)),
+ l4e_from_pfn(mfn, (_PAGE_PRESENT|_PAGE_RW|
+ _PAGE_USER|_PAGE_ACCESSED)), 0);
if ( unlikely(!okay) )
{
MEM_LOG("Error while installing new compat baseptr %lx", mfn);
@@ -1799,39 +1788,13 @@ int new_guest_cr3(unsigned long mfn)
return 1;
}
#endif
- if ( shadow_mode_refcounts(d) )
- {
- okay = get_page_from_pagenr(mfn, d);
- if ( unlikely(!okay) )
- {
- MEM_LOG("Error while installing new baseptr %lx", mfn);
- return 0;
- }
- }
- else
- {
- okay = get_page_and_type_from_pagenr(mfn, PGT_root_page_table, d);
- if ( unlikely(!okay) )
- {
- /* Switch to idle pagetable: this VCPU has no active p.t. now. */
- MEM_LOG("New baseptr %lx: slow path via idle pagetables", mfn);
- old_base_mfn = pagetable_get_pfn(v->arch.guest_table);
- v->arch.guest_table = pagetable_null();
- update_cr3(v);
- write_cr3(__pa(idle_pg_table));
- if ( old_base_mfn != 0 )
- put_page_and_type(mfn_to_page(old_base_mfn));
-
- /* Retry the validation with no active p.t. for this VCPU. */
- okay = get_page_and_type_from_pagenr(mfn, PGT_root_page_table, d);
- if ( !okay )
- {
- /* Failure here is unrecoverable: the VCPU has no pagetable! */
- MEM_LOG("Fatal error while installing new baseptr %lx", mfn);
- domain_crash(d);
- return 0;
- }
- }
+ okay = shadow_mode_refcounts(d)
+ ? get_page_from_pagenr(mfn, d)
+ : get_page_and_type_from_pagenr(mfn, PGT_root_page_table, d);
+ if ( unlikely(!okay) )
+ {
+ MEM_LOG("Error while installing new baseptr %lx", mfn);
+ return 0;
}
invalidate_shadow_ldt(v);
@@ -1839,7 +1802,7 @@ int new_guest_cr3(unsigned long mfn)
old_base_mfn = pagetable_get_pfn(v->arch.guest_table);
v->arch.guest_table = pagetable_from_pfn(mfn);
- update_cr3(v); /* update shadow_table and cr3 fields of vcpu struct */
+ update_cr3(v);
write_ptbase(v);
_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog
|
Home