2017-08-23 22:24:28

by Boris Ostrovsky

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

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 <[email protected]>
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

2017-08-24 06:11:14

by Jürgen Groß

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

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 <[email protected]>
> Fixes: aba831a69632 ("xen: remove tests for pvh mode in pure pv paths")

Reviewed-by: Juergen Gross <[email protected]>


Thanks,

Juergen