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| H A D | spinlock.c | diff fb78e58c275599a961557bca201dd897565833ca Mon Aug 26 13:28:50 CDT 2013 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Revert "xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM"
This reverts commit 70dd4998cb85f0ecd6ac892cc7232abefa432efb.
Now that the bugs have been resolved we can re-enable the
PV ticketlock implementation under PVHVM Xen guests.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
diff 70dd4998cb85f0ecd6ac892cc7232abefa432efb Tue Apr 16 13:34:45 CDT 2013 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM
See git commit f10cd522c5fbfec9ae3cc01967868c9c2401ed23
(xen: disable PV spinlocks on HVM) for details.
But we did not disable it everywhere - which means that when
we boot as PVHVM we end up allocating per-CPU irq line for
spinlock. This fixes that.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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| H A D | smp.c | diff 26a799952737de20626e8c5c51b24534f1c90536 Fri Aug 16 13:39:56 CDT 2013 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> xen/smp: Update pv_lock_ops functions before alternative code starts under PVHVM
Before this patch we would patch all of the pv_lock_ops sites
using alternative assembler. Then later in the bootup cycle
change the unlock_kick and lock_spinning to the Xen specific -
without re patching.
That meant that for the core of the kernel we would be running
with the baremetal version of unlock_kick and lock_spinning while
for modules we would have the proper Xen specific slowpaths.
As most of the module uses some API from the core kernel that ended
up with slowpath lockers waiting forever to be kicked (b/c they
would be using the Xen specific slowpath logic). And the
kick never came b/c the unlock path that was taken was the
baremetal one.
On PV we do not have the problem as we initialise before the
alternative code kicks in.
The fix is to make the updating of the pv_lock_ops function
be done before the alternative code starts patching.
Note that this patch fixes issues discovered by commit
f10cd522c5fbfec9ae3cc01967868c9c2401ed23.
("xen: disable PV spinlocks on HVM") wherein it mentioned
PV spinlocks cannot possibly work with the current code because they are
enabled after pvops patching has already been done, and because PV
spinlocks use a different data structure than native spinlocks so we
cannot switch between them dynamically.
The first problem is solved by this patch.
The second problem has been solved by commit
816434ec4a674fcdb3c2221a6dffdc8f34020550
(Merge branch 'x86-spinlocks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip)
P.S.
There is still the commit 70dd4998cb85f0ecd6ac892cc7232abefa432efb
(xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM) to
revert but that can be done later after all other bugs have been
fixed.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
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