On 2/3/2016 1:48 PM, Ian Campbell wrote:
On Wed, 2016-01-27 at 14:24 +0200, Corneliu ZUZU wrote:
When __p2m_get_mem_access gets called, the p2m lock is already taken
by either get_page_from_gva or p2m_get_mem_access.
Possible code paths:
1) -> get_page_from_gva
-> p2m_mem_access_check_and_get_page
-> __p2m_get_mem_access
2) -> p2m_get_mem_access
-> __p2m_get_mem_access
In both cases if __p2m_get_mem_access subsequently gets to
call p2m_lookup (happens if !radix_tree_lookup(...)), a hypervisor
hang will occur, since p2m_lookup also spin-locks on the p2m lock.
This bug-fix simply replaces the p2m_lookup call from
__p2m_get_mem_access
with a call to __p2m_lookup.
Following Ian's suggestion, we also add an ASSERT to ensure that
the p2m lock is taken upon __p2m_get_mem_access entry.
Signed-off-by: Corneliu ZUZU <cz...@bitdefender.com>
Acked + applied, thanks.
I thought this mail was not sent properly (didn't find it any longer on
the web (?)) and I resent it just earlier.
I figured it must've been the fact that I forgot to put a "Changed since
v1" section & that I didn't include an
"--in-reply-to" option. Apparently it was actually sent correctly.
Sorry, ignore the last one (which contains a "Changed since v1" section).
Corneliu.
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