Patch "kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd" has been added to the 4.2-stable tree

Patch "kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd" has been added to the 4.2-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd

to the 4.2-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-don-t-try-to-register-to-kvm_fast_mmio_bus-for-non-mmio-eventfd.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8453fecbecae26edb3f278627376caab05d9a88d Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Tue, 15 Sep 2015 14:41:54 +0800
Subject: kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd

From: Jason Wang <jasowang@redhat.com>

commit 8453fecbecae26edb3f278627376caab05d9a88d upstream.

We only want zero length mmio eventfd to be registered on
KVM_FAST_MMIO_BUS. So check this explicitly when arg->len is zero to
make sure this.

Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 virt/kvm/eventfd.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -846,7 +846,7 @@ kvm_assign_ioeventfd(struct kvm *kvm, st
 	/* When length is ignored, MMIO is also put on a separate bus, for
 	 * faster lookups.
 	 */
-	if (!args->len && !(args->flags & KVM_IOEVENTFD_FLAG_PIO)) {
+	if (!args->len && bus_idx == KVM_MMIO_BUS) {
 		ret = kvm_io_bus_register_dev(kvm, KVM_FAST_MMIO_BUS,
 					      p->addr, 0, &p->dev);
 		if (ret < 0)
@@ -901,7 +901,7 @@ kvm_deassign_ioeventfd(struct kvm *kvm,
 			continue;
 
 		kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev);
-		if (!p->length) {
+		if (!p->length && p->bus_idx == KVM_MMIO_BUS) {
 			kvm_io_bus_unregister_dev(kvm, KVM_FAST_MMIO_BUS,
 						  &p->dev);
 		}


Patches currently in stable-queue which might be from jasowang@redhat.com are

queue-4.2/kvm-fix-double-free-for-fast-mmio-eventfd.patch
queue-4.2/kvm-fix-zero-length-mmio-searching.patch
queue-4.2/kvm-factor-out-core-eventfd-assign-deassign-logic.patch
queue-4.2/kvm-don-t-try-to-register-to-kvm_fast_mmio_bus-for-non-mmio-eventfd.patch