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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 8f4216c7d28976f7ec1b2bcbfa0a9f787133c45e Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Tue, 15 Sep 2015 14:41:57 +0800
Subject: kvm: fix zero length mmio searching

From: Jason Wang <jasowang@redhat.com>

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.

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

--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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 jasowang@redhat.com are

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