From: David Woodhouse <dwmw@amazon.co.uk>
Date: Fri, 13 Jan 2023 09:51:16 +0000 (+0000)
Subject: Revert "KVM: x86: fix deadlock for KVM_XEN_EVTCHN_RESET"
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=652a19630713424501a2e8529df3f369e92bc047;p=users%2Fdwmw2%2Flinux.git

Revert "KVM: x86: fix deadlock for KVM_XEN_EVTCHN_RESET"

This reverts commit a79b53aaaab53de017517bf9579b6106397a523c.
---

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 651f9c5b873dd..e407fa00ccf4c 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -1959,42 +1959,18 @@ static int kvm_xen_eventfd_deassign(struct kvm *kvm, u32 port)
 
 static int kvm_xen_eventfd_reset(struct kvm *kvm)
 {
-	struct evtchnfd *evtchnfd, **all_evtchnfds;
+	struct evtchnfd *evtchnfd;
 	int i;
-	int n = 0;
 
 	mutex_lock(&kvm->lock);
-
-	/*
-	 * Because synchronize_srcu() cannot be called inside the
-	 * critical section, first collect all the evtchnfd objects
-	 * in an array as they are removed from evtchn_ports.
-	 */
-	idr_for_each_entry(&kvm->arch.xen.evtchn_ports, evtchnfd, i)
-		n++;
-
-	all_evtchnfds = kmalloc_array(n, sizeof(struct evtchnfd *), GFP_KERNEL);
-	if (!all_evtchnfds) {
-		mutex_unlock(&kvm->lock);
-		return -ENOMEM;
-	}
-
-	n = 0;
 	idr_for_each_entry(&kvm->arch.xen.evtchn_ports, evtchnfd, i) {
-		all_evtchnfds[n++] = evtchnfd;
 		idr_remove(&kvm->arch.xen.evtchn_ports, evtchnfd->send_port);
-	}
-	mutex_unlock(&kvm->lock);
-
-	synchronize_srcu(&kvm->srcu);
-
-	while (n--) {
-		evtchnfd = all_evtchnfds[n];
+		synchronize_srcu(&kvm->srcu);
 		if (!evtchnfd->deliver.port.port)
 			eventfd_ctx_put(evtchnfd->deliver.eventfd.ctx);
 		kfree(evtchnfd);
 	}
-	kfree(all_evtchnfds);
+	mutex_unlock(&kvm->lock);
 
 	return 0;
 }
diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index dae510c263b45..721f6a693799b 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -962,12 +962,6 @@ int main(int argc, char *argv[])
 	}
 
  done:
-	struct kvm_xen_hvm_attr evt_reset = {
-		.type = KVM_XEN_ATTR_TYPE_EVTCHN,
-		.u.evtchn.flags = KVM_XEN_EVTCHN_RESET,
-	};
-	vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &evt_reset);
-
 	alarm(0);
 	clock_gettime(CLOCK_REALTIME, &max_ts);