From b3132fc91b611ad07b1b457a56cd9cc113ca6c0e Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 18 Feb 2016 15:05:00 +0100 Subject: [PATCH] x86/mm: slightly simplify mod_l1_entry() Re-order code to simplify error cleanup. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/mm.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index a05edc3da8..ee0ddff9c6 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -1873,38 +1873,32 @@ static int mod_l1_entry(l1_pgentry_t *pl1e, l1_pgentry_t nl1e, { /* Translate foreign guest addresses. */ struct page_info *page = NULL; - if ( paging_mode_translate(pg_dom) ) - { - page = get_page_from_gfn(pg_dom, l1e_get_pfn(nl1e), NULL, P2M_ALLOC); - if ( !page ) - return -EINVAL; - nl1e = l1e_from_pfn(page_to_mfn(page), l1e_get_flags(nl1e)); - } if ( unlikely(l1e_get_flags(nl1e) & l1_disallow_mask(pt_dom)) ) { MEM_LOG("Bad L1 flags %x", l1e_get_flags(nl1e) & l1_disallow_mask(pt_dom)); - if ( page ) - put_page(page); return -EINVAL; } + if ( paging_mode_translate(pg_dom) ) + { + page = get_page_from_gfn(pg_dom, l1e_get_pfn(nl1e), NULL, P2M_ALLOC); + if ( !page ) + return -EINVAL; + nl1e = l1e_from_pfn(page_to_mfn(page), l1e_get_flags(nl1e)); + } + /* Fast path for identical mapping, r/w, presence, and cachability. */ if ( !l1e_has_changed(ol1e, nl1e, PAGE_CACHE_ATTRS | _PAGE_RW | _PAGE_PRESENT) ) { adjust_guest_l1e(nl1e, pt_dom); - if ( UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, - preserve_ad) ) - { - if ( page ) - put_page(page); - return 0; - } + rc = UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, + preserve_ad); if ( page ) put_page(page); - return -EBUSY; + return rc ? 0 : -EBUSY; } switch ( rc = get_page_from_l1e(nl1e, pt_dom, pg_dom) ) -- 2.39.5