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Re: [RFC PATCH] iommu/xen: Add Xen PV-IOMMU driver
- To: Robin Murphy <robin.murphy@xxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>, Jason Gunthorpe <jgg@xxxxxxxx>
- From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
- Date: Tue, 25 Jun 2024 09:18:07 +0800
- Cc: baolu.lu@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, iommu@xxxxxxxxxxxxxxx, Juergen Gross <jgross@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>, Joerg Roedel <joro@xxxxxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Tue, 25 Jun 2024 01:21:16 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 6/24/24 7:09 PM, Robin Murphy wrote:
On 2024-06-23 4:21 am, Baolu Lu wrote:
On 6/21/24 11:09 PM, Teddy Astie wrote:
Le 19/06/2024 à 18:30, Jason Gunthorpe a écrit :
On Thu, Jun 13, 2024 at 01:50:22PM +0000, Teddy Astie wrote:
+struct iommu_domain *xen_iommu_domain_alloc(unsigned type)
+{
+ struct xen_iommu_domain *domain;
+ u16 ctx_no;
+ int ret;
+
+ if (type & IOMMU_DOMAIN_IDENTITY) {
+ /* use default domain */
+ ctx_no = 0;
Please use the new ops, domain_alloc_paging and the static identity
domain.
Yes, in the v2, I will use this newer interface.
I have a question on this new interface : is it valid to not have a
identity domain (and "default domain" being blocking); well in the
current implementation it doesn't really matter, but at some point, we
may want to allow not having it (thus making this driver mandatory).
It's valid to not have an identity domain if "default domain being
blocking" means a paging domain with no mappings.
In the iommu driver's iommu_ops::def_domain_type callback, just always
return IOMMU_DOMAIN_DMA, which indicates that the iommu driver doesn't
support identity translation.
That's not necessary - if neither ops->identity_domain nor
ops->domain_alloc(IOMMU_DOMAIN_IDENTITY) gives a valid domain then we
fall back to IOMMU_DOMAIN_DMA anyway.
Yes. That's true.
Best regards,
baolu
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