From 53a11bbde4e349a490a4648e0ae3e0ae3bdbeb97 Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Tue, 29 Jan 2008 11:50:30 +0000 Subject: [PATCH] x86: Fix shadow pinning logic (for PV live relo). From: Tim Deegan Signed-off-by: Keir Fraser --- xen/arch/x86/mm/shadow/multi.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c index 5a460d9de2..6a8d5e1a15 100644 --- a/xen/arch/x86/mm/shadow/multi.c +++ b/xen/arch/x86/mm/shadow/multi.c @@ -3518,8 +3518,18 @@ sh_set_toplevel_shadow(struct vcpu *v, 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); + if ( !pagetable_is_null(old_entry) ) { + mfn_t old_smfn = pagetable_get_mfn(old_entry); + /* Need to repin the old toplevel shadow if it's been unpinned + * by shadow_prealloc(): in PV mode we're still running on this + * shadow and it's not safe to free it yet. */ + if ( !mfn_to_shadow_page(old_smfn)->pinned && !sh_pin(v, old_smfn) ) + { + SHADOW_ERROR("can't re-pin %#lx\n", mfn_x(old_smfn)); + domain_crash(v->domain); + } + sh_put_ref(v, old_smfn, 0); + } } -- 2.30.2