Commit 8f4216c7 authored Sep 15, 2015 by Jason Wang Committed by Paolo Bonzini Sep 15, 2015

kvm: fix zero length mmio searching



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: stable@vger.kernel.org
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>

parent eefd6b06

virt/kvm/kvm_main.c

+17 −2

Original line number	Diff line number	Diff line
		@@ -3157,10 +3157,25 @@ static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
		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;
		}

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