From 9f6f35b833d295acaaa2d8ff8cf309bf688cfd50 Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Sat, 11 Jan 2020 21:57:42 +0000 Subject: [PATCH 2/3] x86/mm: Refactor modify_xen_mappings to have one exit path We will soon need to perform clean-ups before returning. No functional change. This is part of XSA-345. Reported-by: Hongyan Xia Signed-off-by: Wei Liu Signed-off-by: Hongyan Xia Signed-off-by: George Dunlap Acked-by: Jan Beulich --- xen/arch/x86/mm.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 133a393875..af726d3274 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -5570,6 +5570,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) l1_pgentry_t *pl1e; unsigned int i; unsigned long v = s; + int rc = -ENOMEM; /* Set of valid PTE bits which may be altered. */ #define FLAGS_MASK (_PAGE_NX|_PAGE_RW|_PAGE_PRESENT) @@ -5611,7 +5612,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) /* PAGE1GB: shatter the superpage and fall through. */ pl2e = alloc_xen_pagetable(); if ( !pl2e ) - return -ENOMEM; + goto out; + for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ ) l2e_write(pl2e + i, l2e_from_pfn(l3e_get_pfn(*pl3e) + @@ -5666,7 +5668,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) /* PSE: shatter the superpage and try again. */ pl1e = alloc_xen_pagetable(); if ( !pl1e ) - return -ENOMEM; + goto out; + for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ ) l1e_write(&pl1e[i], l1e_from_pfn(l2e_get_pfn(*pl2e) + i, @@ -5795,7 +5798,10 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf) flush_area(NULL, FLUSH_TLB_GLOBAL); #undef FLAGS_MASK - return 0; + rc = 0; + + out: + return rc; } #undef flush_area -- 2.25.1