From 281e68cc3315b89eb4e7b83a7e54354ced7e8ff4 Mon Sep 17 00:00:00 2001 From: Tim Deegan Date: Thu, 13 Jan 2011 15:46:13 +0000 Subject: [PATCH] x86/mm: fix EPT PoD locking to match the normal p2m case. This recursive-locking bug was fixed in the main p2m code in 20269:fd3d5d66c446 (in October 2009) but has lurked unseen in the EPT side since then. Copy the fix across. Signed-off-by: Tim Deegan --- xen/arch/x86/mm/hap/p2m-ept.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/mm/hap/p2m-ept.c b/xen/arch/x86/mm/hap/p2m-ept.c index 7eebb3253e..fe1d5cd168 100644 --- a/xen/arch/x86/mm/hap/p2m-ept.c +++ b/xen/arch/x86/mm/hap/p2m-ept.c @@ -45,19 +45,26 @@ static int ept_pod_check_and_populate(struct p2m_domain *p2m, unsigned long gfn, ept_entry_t *entry, int order, p2m_query_t q) { + /* Only take the lock if we don't already have it. Otherwise it + * wouldn't be safe to do p2m lookups with the p2m lock held */ + int do_locking = !p2m_locked_by_me(p2m); int r; - p2m_lock(p2m); + + if ( do_locking ) + p2m_lock(p2m); /* Check to make sure this is still PoD */ if ( entry->sa_p2mt != p2m_populate_on_demand ) { - p2m_unlock(p2m); + if ( do_locking ) + p2m_unlock(p2m); return 0; } r = p2m_pod_demand_populate(p2m, gfn, order, q); - p2m_unlock(p2m); + if ( do_locking ) + p2m_unlock(p2m); return r; } -- 2.39.5