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Subject[PATCH 06/10] KVM: Fix hang on uniprocessor
Date
From: Marko Kohtala <marko.kohtala@gmail.com>

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>
---
drivers/kvm/kvm_main.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index cd05579..b514dfb 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -273,6 +273,11 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
}
}

+ /* 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
--
1.5.3


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