[PATCH 2/2] kvm: take srcu lock around kvm_steal_time_set_preempted()

[Andrea Arcangeli]

kvm_memslots() will be called by kvm_write_guest_offset_cached() so
take the srcu lock.

Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
 arch/x86/kvm/x86.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2dabaeb..02e6ab4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2844,6 +2844,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
+	int idx;
 	/*
 	 * Disable page faults because we're in atomic context here.
 	 * kvm_write_guest_offset_cached() would call might_fault()
@@ -2853,7 +2854,13 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	 * paging.
 	 */
 	pagefault_disable();
+	/*
+	 * kvm_memslots() will be called by
+	 * kvm_write_guest_offset_cached() so take the srcu lock.
+	 */
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
 	kvm_steal_time_set_preempted(vcpu);
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
 	pagefault_enable();
 	kvm_x86_ops->vcpu_put(vcpu);
 	kvm_put_guest_fpu(vcpu);