From 4347b980756342e1f9908fc4ae53d788664cb783 Mon Sep 17 00:00:00 2001 From: "kfraser@dhcp93.uk.xensource.com" Date: Thu, 1 Jun 2006 10:50:33 +0100 Subject: [PATCH] [HVM] Fix set_guest_back_ptr to ignore empty PTEs. Signed-off-by: Keir Fraser --- xen/include/asm-x86/shadow.h | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/xen/include/asm-x86/shadow.h b/xen/include/asm-x86/shadow.h index 3a9e0cdf84..32ac908464 100644 --- a/xen/include/asm-x86/shadow.h +++ b/xen/include/asm-x86/shadow.h @@ -756,23 +756,26 @@ shadow_unpin(unsigned long smfn) * when working on finer-gained locks for shadow. */ static inline void set_guest_back_ptr( - struct domain *d, l1_pgentry_t spte, unsigned long smfn, unsigned int index) + struct domain *d, l1_pgentry_t spte, + unsigned long smfn, unsigned int index) { - if ( shadow_mode_external(d) ) { - unsigned long gmfn; - - ASSERT(shadow_lock_is_acquired(d)); - ASSERT( smfn ); - gmfn = l1e_get_pfn(spte); - ASSERT( gmfn ); - if ( l1e_get_flags(spte) & _PAGE_RW ) - { - mfn_to_page(gmfn)->tlbflush_timestamp = smfn; - mfn_to_page(gmfn)->u.inuse.type_info &= ~PGT_va_mask; - mfn_to_page(gmfn)->u.inuse.type_info |= - (unsigned long) index << PGT_va_shift; - } - } + struct page_info *gpage; + + ASSERT(shadow_lock_is_acquired(d)); + + if ( !shadow_mode_external(d) || + ((l1e_get_flags(spte) & (_PAGE_PRESENT|_PAGE_RW)) != + (_PAGE_PRESENT|_PAGE_RW)) ) + return; + + gpage = l1e_get_page(spte); + + ASSERT(smfn != 0); + ASSERT(page_to_mfn(gpage) != 0); + + gpage->tlbflush_timestamp = smfn; + gpage->u.inuse.type_info &= ~PGT_va_mask; + gpage->u.inuse.type_info |= (unsigned long)index << PGT_va_shift; } /************************************************************************/ -- 2.30.2