From e8e9f830dc46ea2bad6919af1fdffc136dfb3aeb Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Sun, 6 Sep 2015 21:05:38 +0100 Subject: [PATCH] libxc: don't populate same pfn more than once in populate_pfns The original implementation of populate_pfns didn't consider the same pfn can be present multiple times in the array. The mechanism to prevent populating the same pfn multiple times only worked if the recurring pfn appeared in different batches. This bug is discovered by Linux 4.1 32 bit kernel save / restore test, which has several ptes pointing to same pfn, which results in an array containing recurring pfn. When libxc called x86_pv_localise_page, the original implementation would populate the same pfn more than once. The fix is to set bit in populated bitmap as we generate list of pfns to be populated. Signed-off-by: Wei Liu Reviewed-by: Andrew Cooper --- tools/libxc/xc_sr_restore.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c index df885b6da0..924dd5534d 100644 --- a/tools/libxc/xc_sr_restore.c +++ b/tools/libxc/xc_sr_restore.c @@ -214,6 +214,9 @@ int populate_pfns(struct xc_sr_context *ctx, unsigned count, types[i] != XEN_DOMCTL_PFINFO_BROKEN))) && !pfn_is_populated(ctx, original_pfns[i]) ) { + rc = pfn_set_populated(ctx, original_pfns[i]); + if ( rc ) + goto err; pfns[nr_pfns] = mfns[nr_pfns] = original_pfns[i]; ++nr_pfns; } @@ -238,9 +241,6 @@ int populate_pfns(struct xc_sr_context *ctx, unsigned count, goto err; } - rc = pfn_set_populated(ctx, pfns[i]); - if ( rc ) - goto err; ctx->restore.ops.set_gfn(ctx, pfns[i], mfns[i]); } } -- 2.30.2