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Groups > linux.kernel > #1718672 > unrolled thread

[PATCH] xen: Don't try to call xen_alloc_p2m_entry() on autotranslating guests

Started byBoris Ostrovsky <boris.ostrovsky@oracle.com>
First post2017-08-24 00:30 +0200
Last post2017-08-24 08:20 +0200
Articles 2 — 2 participants

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  [PATCH] xen: Don't try to call xen_alloc_p2m_entry() on autotranslating guests Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-08-24 00:30 +0200
    Re: [PATCH] xen: Don't try to call xen_alloc_p2m_entry() on  autotranslating guests Juergen Gross <jgross@suse.com> - 2017-08-24 08:20 +0200

#1718672 — [PATCH] xen: Don't try to call xen_alloc_p2m_entry() on autotranslating guests

FromBoris Ostrovsky <boris.ostrovsky@oracle.com>
Date2017-08-24 00:30 +0200
Subject[PATCH] xen: Don't try to call xen_alloc_p2m_entry() on autotranslating guests
Message-ID<uhMjT-6nQ-1@gated-at.bofh.it>
Commit aba831a69632 ("xen: remove tests for pvh mode in pure pv paths")
removed XENFEAT_auto_translated_physmap test in xen_alloc_p2m_entry()
since it is assumed that the routine is never called by non-PV guests.

However, alloc_xenballooned_pages() may make this call on a PVH guest.
Prevent this from happening by adding XENFEAT_auto_translated_physmap
check there.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Fixes: aba831a69632 ("xen: remove tests for pvh mode in pure pv paths")
---
 drivers/xen/balloon.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ab60925..f77e499 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -664,9 +664,11 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages)
 			 */
 			BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
 
-			ret = xen_alloc_p2m_entry(page_to_pfn(page));
-			if (ret < 0)
-				goto out_undo;
+			if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+				ret = xen_alloc_p2m_entry(page_to_pfn(page));
+				if (ret < 0)
+					goto out_undo;
+			}
 #endif
 		} else {
 			ret = add_ballooned_pages(nr_pages - pgno);
-- 
1.8.3.1

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#1718863 — Re: [PATCH] xen: Don't try to call xen_alloc_p2m_entry() on autotranslating guests

FromJuergen Gross <jgross@suse.com>
Date2017-08-24 08:20 +0200
SubjectRe: [PATCH] xen: Don't try to call xen_alloc_p2m_entry() on autotranslating guests
Message-ID<uhTEK-2Mj-7@gated-at.bofh.it>
In reply to#1718672
On 24/08/17 00:27, Boris Ostrovsky wrote:
> Commit aba831a69632 ("xen: remove tests for pvh mode in pure pv paths")
> removed XENFEAT_auto_translated_physmap test in xen_alloc_p2m_entry()
> since it is assumed that the routine is never called by non-PV guests.
> 
> However, alloc_xenballooned_pages() may make this call on a PVH guest.
> Prevent this from happening by adding XENFEAT_auto_translated_physmap
> check there.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Fixes: aba831a69632 ("xen: remove tests for pvh mode in pure pv paths")

Reviewed-by: Juergen Gross <jgross@suse.com>


Thanks,

Juergen

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