Re: [PATCH 1/2] s390x/pci: add support for guests that request direct mapping

[Thomas Huth <thuth@redhat.com>]

On 09/12/2024 20.29, Matthew Rosato wrote:
> When receiving a guest mpcifc(4) or mpcifc(6) instruction without the T
> bit set, treat this as a request to perform direct mapping instead of
> address translation.  In order to facilitiate this, pin the entirety of

s/facilitiate/facilitate/

> guest memory into the host iommu.
...
> +void s390_pci_iommu_dm_enable(S390PCIIOMMU *iommu)
> +{
> +    MachineState *ms = MACHINE(qdev_get_machine());
> +
> +    /*
> +     * For direct-mapping we must map the entire guest address space.  Because
> +     * the mappings are contiguous we are not restricted to individual 4K
> +     * mappings via vfio, so let's not worry about the DMA limit when
> +     * calculating the range.
> +     */
> +    char *name = g_strdup_printf("iommu-s390-%04x", iommu->pbdev->uid);

FWIW, you could use g_autofree to get rid of the g_free() at the end of the 
function.

> +    memory_region_init_iommu(&iommu->iommu_mr, sizeof(iommu->iommu_mr),
> +                             TYPE_S390_IOMMU_MEMORY_REGION, OBJECT(&iommu->mr),
> +                             name, iommu->pba + ms->ram_size);
> +    iommu->enabled = true;
> +    iommu->direct_map = true;
>       memory_region_add_subregion(&iommu->mr, 0, MEMORY_REGION(&iommu->iommu_mr));
>       g_free(name);
>   }

  Thomas