From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: [PATCH 3/3] xen: arm: correctly handle removing a subset of a superpage mapping. Date: Mon, 14 Jul 2014 17:27:05 +0100 Message-ID: <1405355225-4623-3-git-send-email-ian.campbell@citrix.com> References: <1405355194.31863.2.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1405355194.31863.2.camel@kazak.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: julien.grall@linaro.org, tim@xen.org, Ian Campbell , stefano.stabellini@eu.citrix.com List-Id: xen-devel@lists.xenproject.org This can be exercised for example via ballooning which will remove 4K regions fromanywhere in the address space. Reported-by: Julien Grall Signed-off-by: Ian Campbell --- 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