[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 3/3] xen: arm: correctly handle removing a subset of a superpage mapping.
This can be exercised for example via ballooning which will remove 4K regions fromanywhere in the address space. Reported-by: Julien Grall <julien.grall@xxxxxxxxxx> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> --- xen/arch/arm/p2m.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index a10cbaf..68a19bd 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -604,8 +604,33 @@ static int apply_one_level(struct domain *d, return P2M_ONE_PROGRESS_NOP; } - if ( level < 3 && p2m_table(orig_pte) ) - return P2M_ONE_DESCEND; + if ( level < 3 ) + { + if ( p2m_table(orig_pte) ) + return P2M_ONE_DESCEND; + + if ( op == REMOVE && + !is_mapping_aligned(*addr, end_gpaddr, + 0, /* maddr doesn't matter for remove */ + level_size) ) + { + /* + * Removing a mapping from the middle of a superpage. Shatter + * and descend. + */ + *flush = true; + rc = p2m_create_table(d, entry, + level_shift - PAGE_SHIFT, flush_cache); + if ( rc < 0 ) + return rc; + + p2m->stats.shattered[level]++; + p2m->stats.mappings[level]--; + p2m->stats.mappings[level+1] += LPAE_ENTRIES; + + return P2M_ONE_DESCEND; + } + } *flush = true; -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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