Re: [PATCH] xio3130_downstream: Add ACS (Access Control Services) capability

[Philippe Mathieu-Daudé]

Hi Paul,

On 31/1/23 07:30, wlfightup wrote:
> When vfio-pci devices are attached to the downstream, pcie acs
> capability may be needed, Consistent with physical machine.
>
> It has been tested in our environment, and pcie acs capability
> is required in some scenarios.
>
> Claim ACS support in the downstream port to allow
> passthrough of individual functions of a device to different
> guests (in a nested virt.setting) with VFIO.
> Without this patch, all functions of a device, such as all VFs of
> an SR/IOV device, will end up in the same IOMMU group.
> A similar situation occurs on Windows with Hyper-V.
>
> Signed-off-by: wlfightup <wlfightup@gmail.com>

Please use your real name, "Paul Schlacter <wlfightup@gmail.com>"
See https://www.qemu.org/docs/master/devel/submitting-a-patch.html

Cc'ing VFIO maintainers.

Regards,

Phil.

> ---
>   hw/pci-bridge/xio3130_downstream.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/hw/pci-bridge/xio3130_downstream.c 
> b/hw/pci-bridge/xio3130_downstream.c
> index 38a2361fa2..2017cf42a3 100644
> --- a/hw/pci-bridge/xio3130_downstream.c
> +++ b/hw/pci-bridge/xio3130_downstream.c
> @@ -40,6 +40,8 @@
>   #define XIO3130_SSVID_SSID              0
>   #define XIO3130_EXP_OFFSET              0x90
>   #define XIO3130_AER_OFFSET              0x100
> +#define XIO3130_ACS_OFFSET \
> +        (XIO3130_AER_OFFSET + PCI_ERR_SIZEOF)
>   
>   static void xio3130_downstream_write_config(PCIDevice *d, uint32_t address,
>                                            uint32_t val, int len)
> @@ -111,6 +113,10 @@ static void xio3130_downstream_realize(PCIDevice *d, Error 
> **errp)
>           goto err;
>       }
>   
> +    if (!s->disable_acs) {
> +        pcie_acs_init(d, XIO3130_ACS_OFFSET);
> +    }
> +
>       return;
>   
>   err:
> @@ -137,6 +143,7 @@ static void xio3130_downstream_exitfn(PCIDevice *d)
>   static Property xio3130_downstream_props[] = {
>       DEFINE_PROP_BIT(COMPAT_PROP_PCP, PCIDevice, cap_present,
>                       QEMU_PCIE_SLTCAP_PCP_BITNR, true),
> +    DEFINE_PROP_BOOL("x-disable-acs", PCIESlot, disable_acs, true),
>       DEFINE_PROP_END_OF_LIST()
>   };
>