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    SubjectRe: [PATCH v3 01/20] virtio: mmio-v1: Validate queue PFN
    On Tue, Jul 03, 2018 at 09:04:01AM +0100, Suzuki K Poulose wrote:
    > Hi Michael,
    >
    > On 06/29/2018 06:42 PM, Michael S. Tsirkin wrote:
    > > On Fri, Jun 29, 2018 at 12:15:21PM +0100, Suzuki K Poulose wrote:
    > > > virtio-mmio with virtio-v1 uses a 32bit PFN for the queue.
    > > > If the queue pfn is too large to fit in 32bits, which
    > > > we could hit on arm64 systems with 52bit physical addresses
    > > > (even with 64K page size), we simply miss out a proper link
    > > > to the other side of the queue.
    > > >
    > > > Add a check to validate the PFN, rather than silently breaking
    > > > the devices.
    > > >
    > > > Cc: "Michael S. Tsirkin" <mst@redhat.com>
    > > > Cc: Jason Wang <jasowang@redhat.com>
    > > > Cc: Marc Zyngier <marc.zyngier@arm.com>
    > > > Cc: Christoffer Dall <cdall@kernel.org>
    > > > Cc: Peter Maydel <peter.maydell@linaro.org>
    > > > Cc: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
    > > > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    > > > ---
    > > > Changes since v2:
    > > > - Change errno to -E2BIG
    > > > ---
    > > > drivers/virtio/virtio_mmio.c | 18 ++++++++++++++++--
    > > > 1 file changed, 16 insertions(+), 2 deletions(-)
    > > >
    > > > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
    > > > index 67763d3..82cedc8 100644
    > > > --- a/drivers/virtio/virtio_mmio.c
    > > > +++ b/drivers/virtio/virtio_mmio.c
    > > > @@ -397,9 +397,21 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
    > > > /* Activate the queue */
    > > > writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
    > > > if (vm_dev->version == 1) {
    > > > + u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;
    > > > +
    > > > + /*
    > > > + * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
    > > > + * that doesn't fit in 32bit, fail the setup rather than
    > > > + * pretending to be successful.
    > > > + */
    > > > + if (q_pfn >> 32) {
    > > > + dev_err(&vdev->dev, "virtio-mmio: queue address too large\n");
    > >
    > > How about:
    > > "hypervisor bug: legacy virtio-mmio must not be used with more than 0x%llx Gigabytes of memory",
    > > 0x1ULL << (32 - 30) << PAGE_SHIFT
    >
    > nit : Do we need change "hypervisor" => "platform" ? Virtio is used by other
    > tools (e.g, emulators) and not just virtual machines.
    >
    > Suzuki

    OK.

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