On Sun, Sep 29, 2024 at 03:16:55PM +0800, Yi Liu wrote: > > > > I feel these two might act somehow similarly to the two DIDs > > > > during nested translations? > > > > > > not quite the same. Is it possible that the ASID is the same for stage-1? > > > Intel VT-d side can have the pasid to be the same. Like the gIOVA, all > > > devices use the same ridpasid. Like the scenario I replied to Baolu[1], > > > do er choose to use different DIDs to differentiate the caches for the > > > two devices. > > > > On ARM, each S1 domain (either a normal stage-1 PASID=0 domain or > > an SVA PASID>0 domain) has a unique ASID. > > I see. Looks like ASID is not the PASID. It's not. PASID is called Substream ID in SMMU term. It's used to index the PASID table. For cache invalidations, a PASID (ssid) is for ATC (dev cache) or PASID table entry invalidation only. > > So it unlikely has the > > situation of two identical ASIDs if they are on the same vIOMMU, > > because the ASID pool is per IOMMU instance (whether p or v). > > > > With two vIOMMU instances, there might be the same ASIDs but they > > will be tagged with different VMIDs. > > > > > [1] > > > https://lore.kernel.org/linux-iommu/4bc9bd20-5aae-440d-84fd-f530d0747c23@xxxxxxxxx/ > > > > Is "gIOVA" a type of invalidation that only uses "address" out of > > "PASID, DID and address"? I.e. PASID and DID are not provided via > > the invalidation request, so it's going to broadcast all viommus? > > gIOVA is just a term v.s. vSVA. Just want to differentiate it from vSVA. :) > PASID and DID are still provided in the invalidation. I am still not getting this gIOVA. What it does exactly v.s. vSVA? And should RIDPASID be IOMMU_NO_PASID? Nicolin
