# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
# Node ID 658b9c47db98bbfff19b6851972a82939c9e37d0
# Parent 3b961863062d1f5a7aaf38ed3bdb8943b095c770
[XEN] Don't unpin old shadow top levels until the new ones are pinned.
This will stop a possible case where we unshadow an entire process
on a TLB-flush CR3 write.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>
---
xen/arch/x86/mm/shadow/multi.c | 25 +++++++++++++++----------
1 files changed, 15 insertions(+), 10 deletions(-)
diff -r 3b961863062d -r 658b9c47db98 xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c Mon Nov 27 20:04:20 2006 +0000
+++ b/xen/arch/x86/mm/shadow/multi.c Tue Nov 28 09:39:32 2006 +0000
@@ -3294,20 +3294,18 @@ sh_set_toplevel_shadow(struct vcpu *v,
unsigned int root_type)
{
mfn_t smfn;
+ pagetable_t old_entry, new_entry;
+
struct domain *d = v->domain;
- /* Decrement the refcount of the old contents of this slot */
- smfn = pagetable_get_mfn(v->arch.shadow_table[slot]);
- if ( mfn_x(smfn) )
- sh_put_ref(v, smfn, 0);
+ /* Remember the old contents of this slot */
+ old_entry = v->arch.shadow_table[slot];
/* Now figure out the new contents: is this a valid guest MFN? */
if ( !valid_mfn(gmfn) )
{
- SHADOW_PRINTK("%u/%u [%u] invalid gmfn\n",
- GUEST_PAGING_LEVELS, SHADOW_PAGING_LEVELS, slot);
- v->arch.shadow_table[slot] = pagetable_null();
- return;
+ new_entry = pagetable_null();
+ goto install_new_entry;
}
/* Guest mfn is valid: shadow it and install the shadow */
@@ -3342,11 +3340,18 @@ sh_set_toplevel_shadow(struct vcpu *v,
domain_crash(v->domain);
}
+ new_entry = pagetable_from_mfn(smfn);
+
+ install_new_entry:
/* Done. Install it */
SHADOW_PRINTK("%u/%u [%u] gmfn %#"SH_PRI_mfn" smfn %#"SH_PRI_mfn"\n",
GUEST_PAGING_LEVELS, SHADOW_PAGING_LEVELS, slot,
- mfn_x(gmfn), mfn_x(smfn));
- v->arch.shadow_table[slot] = pagetable_from_mfn(smfn);
+ mfn_x(gmfn), mfn_x(pagetable_get_mfn(new_entry)));
+ v->arch.shadow_table[slot] = new_entry;
+
+ /* Decrement the refcount of the old contents of this slot */
+ if ( !pagetable_is_null(old_entry) )
+ sh_put_ref(v, pagetable_get_mfn(old_entry), 0);
}
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