Re: [PATCH v10 7/7] xen/arm: Map ITS doorbell register to IOMMU page tables

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 29 Apr 2025, Mykyta Poturai wrote:
> From: Rahul Singh <rahul.singh@xxxxxxx>
> 
> When ITS is enabled and PCI devices that are behind an SMMU generate an
> MSI interrupt, SMMU fault will be observed as there is currently no
> mapping in p2m table for the ITS translation register (GITS_TRANSLATER).
> 
> A mapping is required in the iommu page tables so that the device can
> generate the MSI interrupt writing to the GITS_TRANSLATER register.
> 
> The GITS_TRANSLATER register is a 32-bit register, and there is nothing
> else in a page containing it, so map that page.
> 
> Add new host_addr parameter to vgic_v3_its_init_virtual to prepare the
> foundation for DomU MSI support where guest doorbell address can differ
> for the host's. Note that the 1:1 check in arm_iommu_map_page remains
> for now, as virtual ITSes are currently only created for hwdom where the
> doorbell mapping is always 1:1.
> 
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
> Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>