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SubjectRe: [PATCH v1 01/16] virtio: Validate queue pfn for 32bit transports
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On 09/01/18 23:29, Michael S. Tsirkin wrote:
> On Tue, Jan 09, 2018 at 07:03:56PM +0000, Suzuki K Poulose wrote:
>> virtio-mmio using virtio-v1 and virtio legacy pci use 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@linaro.org>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>
> Could you guys please work on virtio 1 support in
> for virtio mmio in qemu though?
> It's not a lot of code.

Did you mean kvmtool ? Qemu already supports virto-1.

>
>> ---
>> drivers/virtio/virtio_mmio.c | 19 ++++++++++++++++---
>> drivers/virtio/virtio_pci_legacy.c | 11 +++++++++--
>> 2 files changed, 25 insertions(+), 5 deletions(-)
>
> I'd rather see this as 2 patches.

OK, I will split them.

>
>> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
>> index a9192fe4f345..47109baf37f7 100644
>> --- a/drivers/virtio/virtio_mmio.c
>> +++ b/drivers/virtio/virtio_mmio.c
>> @@ -358,6 +358,7 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
>> struct virtqueue *vq;
>> unsigned long flags;
>> unsigned int num;
>> + u64 addr;
>> int err;
>>
>> if (!name)
>> @@ -394,16 +395,26 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
>> goto error_new_virtqueue;
>> }
>>
>> + addr = virtqueue_get_desc_addr(vq);
>> + /*
>> + * 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 (vm_dev->version == 1 && (addr >> (PAGE_SHIFT + 32))) {
>> + dev_err(&vdev->dev, "virtio-mmio: queue address too large\n");
>> + err = -ENOMEM;
>> + goto error_bad_pfn;
>> + }
>> +
>
> Can you please move this below to where it's actually used?
>

The reason for keeping it here was to skip selecting the Queue number if we
have a bad PFN. May be it doesn't make much difference as we write PFN = 0 anyway
down.

>> /* Activate the queue */
>> writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
>> if (vm_dev->version == 1) {
>> writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
>> - writel(virtqueue_get_desc_addr(vq) >> PAGE_SHIFT,
>> + writel(addr >> PAGE_SHIFT,
>> vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
>> } else {
>> - u64 addr;
>>
>> - addr = virtqueue_get_desc_addr(vq);
>> writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
>> writel((u32)(addr >> 32),
>> vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
>> @@ -430,6 +441,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
>>
>> return vq;
>>
>> +error_bad_pfn:
>> + vring_del_virtqueue(vq);
>> error_new_virtqueue:
>> if (vm_dev->version == 1) {
>> writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
>> diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
>> index 2780886e8ba3..099d2cfb47b3 100644
>> --- a/drivers/virtio/virtio_pci_legacy.c
>> +++ b/drivers/virtio/virtio_pci_legacy.c
>> @@ -122,6 +122,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
>> struct virtqueue *vq;
>> u16 num;
>> int err;
>> + u64 q_pfn;
>>
>> /* Select the queue we're interested in */
>> iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
>> @@ -141,9 +142,15 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
>> if (!vq)
>> return ERR_PTR(-ENOMEM);
>>
>> + q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
>> + if (q_pfn >> 32) {
>> + dev_err(&vp_dev->pci_dev->dev, "virtio-pci queue PFN too large\n");
>> + err = -ENOMEM;
>> + goto out_deactivate;
>
> You never set up the address, it's cleaner to add another target
> and not reset it.

Thats right. However, the only thing we do is writing PFN=0, which would be a good
thing to do to indicate the error to the host ? I could skip it if you think it is
not needed.


Thanks
Suzuki

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