Hi Stewart,

> On 7 Jul 2023, at 2:47 am, Stewart Hildebrand <Stewart.Hildebrand@amd.com> wrote:
>
> Remove is_hardware_domain check in has_vpci, and select HAS_VPCI_GUEST_SUPPORT
> in Kconfig.
>
> [1] https://lists.xenproject.org/archives/html/xen-devel/2023-06/msg00863.html
>
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com>
> ---
> As the tag implies, this patch is not intended to be merged (yet).
>
> Note that CONFIG_HAS_VPCI_GUEST_SUPPORT is not currently used in the upstream
> code base. It will be used by the vPCI series [1]. This patch is intended to be
> merged as part of the vPCI series.
>
> v1->v2:
> * new patch
> ---
> xen/arch/arm/Kconfig              | 1 +
> xen/arch/arm/include/asm/domain.h | 2 +-
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> index 4e0cc421ad48..75dfa2f5a82d 100644
> --- a/xen/arch/arm/Kconfig
> +++ b/xen/arch/arm/Kconfig
> @@ -195,6 +195,7 @@ config PCI_PASSTHROUGH
> depends on ARM_64
> select HAS_PCI
> select HAS_VPCI
> + select HAS_VPCI_GUEST_SUPPORT

I tested this series on top of "SMMU handling for PCIe Passthrough on ARM” series on the N1SDP board
and observe the SMMUv3 fault.

Enable the Kconfig option PCI_PASSTHROUGH, ARM_SMMU_V3,HAS_ITS and "iommu=on”,
"pci_passthrough_enabled=on" cmd line parameter and after that, there is an SMMU fault
for the ITS doorbell register access from the PCI devices.

As there is no upstream support for ARM for vPCI MSI/MSI-X handling because of that SMMU fault is observed.

Linux Kernel will set the ITS doorbell register( physical address of doorbell register as IOMMU is not enabled in Kernel)
in PCI config space to set up the MSI-X interrupts, but there is no mapping in SMMU page tables because of that SMMU
fault is observed. To fix this we need to map the ITS doorbell register to SMMU page tables to avoid the fault.

We can fix this after setting the mapping for the ITS doorbell offset in the ITS code.

diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
index 299b384250..8227a7a74b 100644
--- a/xen/arch/arm/vgic-v3-its.c
+++ b/xen/arch/arm/vgic-v3-its.c
@@ -682,6 +682,18 @@ static int its_handle_mapd(struct virt_its *its, uint64_t *cmdptr)
                                          BIT(size, UL), valid);
         if ( ret && valid )
             return ret;
+
+        if ( is_iommu_enabled(its->d) ) {
+            ret = map_mmio_regions(its->d, gaddr_to_gfn(its->doorbell_address),
+                           PFN_UP(ITS_DOORBELL_OFFSET),
+                           maddr_to_mfn(its->doorbell_address));
+            if ( ret < 0 )
+            {
+                printk(XENLOG_ERR "GICv3: Map ITS translation register d%d failed.\n",
+                        its->d->domain_id);
+                return ret;
+            }
+        }
     }

Also as per Julien's request, I tried to set up the IOMMU for the PCI device without
"pci_passthroigh_enable=on" and without HAS_VPCI everything works as expected
after applying below patches.

To test enable kconfig options HAS_PCI, ARM_SMMU_V3 and HAS_ITS and add below
patches to make it work.

    • Set the mapping for the ITS doorbell offset in the ITS code when iommu is enabled.
    • Reverted the patch that added the support for pci_passthrough_on.
    • Allow MMIO mapping of ECAM space to dom0 when vPCI is not enabled, as of now MMIO
      mapping for ECAM is based on pci_passthrough_enabled. We need this patch if we want to avoid
     enabling HAS_VPCI

Please find the attached patches in case you want to test at your end.