We could use PCI_NO_PASID (-1) but need to translate from PASID_0 to PCI_NO_PASID in intel_iommu, IOMMU_NO_PASID(0) which equals PASID_0 looks more straight-forward for me, I plan to define it in include/hw/core/iommu.h
From: CLEMENT MATHIEU--DRIF <[email protected]> Sent: Thursday, February 12, 2026 2:45 PM To: Duan, Zhenzhong <[email protected]>; Nicolin Chen <[email protected]>; Shameer Kolothum Thodi <[email protected]> Cc: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Jason Gunthorpe <[email protected]>; [email protected]; Tian, Kevin <[email protected]>; Liu, Yi L <[email protected]>; Hao, Xudong <[email protected]> Subject: Re: [RFC PATCH 01/14] backends/iommufd: Add pasid attach/detach callbacks What about PCI_NO_PASID? ________________________________ From: Duan, Zhenzhong <[email protected]<mailto:[email protected]>> Sent: 12 February 2026 03:43 To: Nicolin Chen <[email protected]<mailto:[email protected]>>; Shameer Kolothum Thodi <[email protected]<mailto:[email protected]>> Cc: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; Jason Gunthorpe <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>; CLEMENT MATHIEU--DRIF <[email protected]<mailto:[email protected]>>; Tian, Kevin <[email protected]<mailto:[email protected]>>; Liu, Yi L <[email protected]<mailto:[email protected]>>; Hao, Xudong <[email protected]<mailto:[email protected]>> Subject: RE: [RFC PATCH 01/14] backends/iommufd: Add pasid attach/detach callbacks Caution: External email. Do not open attachments or click links, unless this email comes from a known sender and you know the content is safe. >-----Original Message----- >From: Nicolin Chen <[email protected]<mailto:[email protected]>> >Subject: Re: [RFC PATCH 01/14] backends/iommufd: Add pasid attach/detach >callbacks > >On Wed, Feb 11, 2026 at 09:14:33AM -0800, Shameer Kolothum Thodi wrote: >> > > Have you considered extending attach_hwpt() to >> > >take a PASID instead of introducing a separate callback? >> > >> > Yes, I did. To extending attach/detach_hwpt(), we need to add two >> > parameters, "bool has_pasid, uint32_t pasid". E.g., >> > >> > bool (*attach_hwpt)(HostIOMMUDeviceIOMMUFD *idev, >> > bool has_pasid, uint32_t pasid, >> > uint32_t hwpt_id, Error **errp); > >The RID attach/detach could be just pasid=IOMMU_NO_PASID without >that "has_pasid"? After further thinking, yes, we could. IOMMU_NO_PASID isn't export as UAPI, we need to define it in QEMU. > >> > and refactor iommufd_cdev_attach/detach_ioas_hwpt() a bit. >> > >> > I'm fine either way, two separate callbacks just look cleaner for me. >> > Let me know if extending is preferred. >> >> Since PASID attach/detach is essentially an extension of the existing >> attach/detach flow, I would prefer extending the current callbacks. >> I think that keeps the interface simpler and avoids code duplication. > >+1 Ok, wll extend attach/detach_hwpt(). Thanks all.
