[PATCH 02/14] x86/mem-sharing: Don't leave the altp2m lock held when nominating a page

From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xen.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Tamas K Lengyel" <tamas@tklengyel.com>,
	"Wei Liu" <wei.liu2@citrix.com>,
	"Jan Beulich" <JBeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [PATCH 02/14] x86/mem-sharing: Don't leave the altp2m lock held when nominating a page
Date: Wed, 21 Nov 2018 13:21:10 +0000	[thread overview]
Message-ID: <1542806482-24030-3-git-send-email-andrew.cooper3@citrix.com> (raw)
In-Reply-To: <1542806482-24030-1-git-send-email-andrew.cooper3@citrix.com>

get_gfn_type_access() internally takes the p2m lock, and nothing ever unlocks
it.  Switch to using the unlocked accessor instead.

This wasn't included in XSA-277 because neither mem-sharing nor altp2m are
supported.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Tamas K Lengyel <tamas@tklengyel.com>
---
 xen/arch/x86/mm/mem_sharing.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index f4c5074..77f0d3f 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -820,7 +820,8 @@ static int nominate_page(struct domain *d, gfn_t gfn,
             if ( !ap2m )
                 continue;
 
-            amfn = get_gfn_type_access(ap2m, gfn_x(gfn), &ap2mt, &ap2ma, 0, NULL);
+            amfn = __get_gfn_type_access(ap2m, gfn_x(gfn), &ap2mt, &ap2ma,
+                                         0, NULL, false);
             if ( mfn_valid(amfn) && (!mfn_eq(amfn, mfn) || ap2ma != p2ma) )
             {
                 altp2m_list_unlock(d);
-- 
2.1.4


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