This is a note to let you know that I've just added the patch titled
kvm: cap halt polling at exactly halt_poll_ns
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-cap-halt-polling-at-exactly-halt_poll_ns.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 313f636d5c490c9741d3f750dc8da33029edbc6b Mon Sep 17 00:00:00 2001
From: David Matlack <dmatlack@xxxxxxxxxx>
Date: Tue, 8 Mar 2016 16:19:44 -0800
Subject: kvm: cap halt polling at exactly halt_poll_ns
From: David Matlack <dmatlack@xxxxxxxxxx>
commit 313f636d5c490c9741d3f750dc8da33029edbc6b upstream.
When growing halt-polling, there is no check that the poll time exceeds
the limit. It's possible for vcpu->halt_poll_ns grow once past
halt_poll_ns, and stay there until a halt which takes longer than
vcpu->halt_poll_ns. For example, booting a Linux guest with
halt_poll_ns=11000:
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 0 (shrink 10000)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 10000 (grow 0)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 20000 (grow 10000)
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
Fixes: aca6ff29c4063a8d467cdee241e6b3bf7dc4a171
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
virt/kvm/kvm_main.c | 3 +++
1 file changed, 3 insertions(+)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1961,6 +1961,9 @@ static void grow_halt_poll_ns(struct kvm
else
val *= halt_poll_ns_grow;
+ if (val > halt_poll_ns)
+ val = halt_poll_ns;
+
vcpu->halt_poll_ns = val;
trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
}
Patches currently in stable-queue which might be from dmatlack@xxxxxxxxxx are
queue-4.4/kvm-cap-halt-polling-at-exactly-halt_poll_ns.patch
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