Patch "kvm: fix zero length mmio searching" has been added to the 3.14-stable tree

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

kvm: fix zero length mmio searching

to the 3.14-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-fix-zero-length-mmio-searching.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jason Wang <[email protected]>
Date: Tue, 15 Sep 2015 14:41:57 +0800
Subject: kvm: fix zero length mmio searching

From: Jason Wang <[email protected]>

commit 8f4216c7d28976f7ec1b2bcbfa0a9f787133c45e upstream.

Currently, if we had a zero length mmio eventfd assigned on KVM_MMIO_BUS. It will never be found by kvm_io_bus_cmp() since it always compares the kvm_io_range() with the length that guest wrote. This will cause e.g for vhost, kick will be trapped by qemu userspace instead of vhost. Fixing this by using zero length if an iodevice is zero length.

---
 virt/kvm/kvm_main.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

@@ -2797,10 +2797,25 @@ static void kvm_io_bus_destroy(struct kv
 static inline int kvm_io_bus_cmp(const struct kvm_io_range *r1,
                                  const struct kvm_io_range *r2)
 {
-	if (r1->addr < r2->addr)
+	gpa_t addr1 = r1->addr;
+	gpa_t addr2 = r2->addr;
+
+	if (addr1 < addr2)
 		return -1;
-	if (r1->addr + r1->len > r2->addr + r2->len)
+
+	/* If r2->len == 0, match the exact address.  If r2->len != 0,
+	 * accept any overlapping write.  Any order is acceptable for
+	 * overlapping ranges, because kvm_io_bus_get_first_dev ensures
+	 * we process all of them.
+	 */
+	if (r2->len) {
+		addr1 += r1->len;
+		addr2 += r2->len;
+	}
+
+	if (addr1 > addr2)
 		return 1;
+
 	return 0;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/kvm-fix-zero-length-mmio-searching.patch