Re: [PATCH] pci: advertise a page aligned ATS

[Jason Wang <jasowang@redhat.com>]

On 2020/9/9 下午4:17, Jason Wang wrote:
> After Linux kernel commit 61363c1474b1 ("iommu/vt-d: Enable ATS only
> if the device uses page aligned address."), ATS will be only enabled
> if device advertises a page aligned request.
>
> Unfortunately, vhost-net is the only user and we don't advertise the
> aligned request capability in the past since both vhost IOTLB and
> address_space_get_iotlb_entry() can support non page aligned request.
>
> Though it's not clear that if the above kernel commit makes
> sense. Let's advertise a page aligned ATS here to make vhost device
> IOTLB work with Intel IOMMU again.
>
> Note that in the future we may extend pcie_ats_init() to accept
> parameters like queue depth and page alignment.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>   hw/pci/pcie.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index 5b48bae0f6..d4010cf8f3 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -971,8 +971,9 @@ void pcie_ats_init(PCIDevice *dev, uint16_t offset)
>   
>       dev->exp.ats_cap = offset;
>   
> -    /* Invalidate Queue Depth 0, Page Aligned Request 0 */
> -    pci_set_word(dev->config + offset + PCI_ATS_CAP, 0);
> +    /* Invalidate Queue Depth 0, Page Aligned Request 1 */
> +    pci_set_word(dev->config + offset + PCI_ATS_CAP,
> +                 PCI_ATS_CAP_PAGE_ALIGNED);
>       /* STU 0, Disabled by default */
>       pci_set_word(dev->config + offset + PCI_ATS_CTRL, 0);
>   


Ping, Michael, want to pick this patch?

Thanks