[patch 22/60] KVM: Fix hang on uniprocessor

Greg KH
2007-12-13T07:04:52Z

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2.6.23-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Marko Kohtala <marko.kohtala@gmail.com>

This is not in mainline, as it was fixed differently in that tree.

first_cpu(cpus) returns the only CPU when NR_CPUS is 1 regardless of
the cpus mask. Therefore we avoid a kernel hang in
KVM_SET_MEMORY_REGION ioctl on uniprocessor by not entering the loop at
all.

Signed-off-by: Marko Kohtala <marko.kohtala@gmail.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/kvm/kvm_main.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -273,6 +273,11 @@ void kvm_flush_remote_tlbs(struct kvm *k
}
}

+ /* Uniprocessor kernel does not respect cpus in first_cpu. So
+ * do not go there if we have nothing to do. */
+ if (cpus_empty(cpus))
+ return;
+
/*
* We really want smp_call_function_mask() here. But that's not
* available, so ipi all cpus in parallel and wait for them

--