linux-kernel - RE: [PATCH v2 1/1] PCI: Add translated request only flag for pci_enable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 13 Jan 2023 02:24:33 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rodel, Jorg" <jroedel@...e.de>
CC:     Christian König <christian.koenig@....com>,
        "Jason Gunthorpe" <jgg@...dia.com>,
        Vasant Hegde <vasant.hegde@....com>,
        "Zhu, Tony" <tony.zhu@...el.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matt Fagnani <matt.fagnani@...l.net>
Subject: RE: [PATCH v2 1/1] PCI: Add translated request only flag for
 pci_enable_pasid()

> From: Lu Baolu <baolu.lu@...ux.intel.com>
> Sent: Friday, January 13, 2023 9:44 AM
> 
> One alternative is ATS which lets the device resolve the PASID+addr pair
> before a memory request is made into a routeable TLB address through the
> TA. Those resolved addresses are then cached on the device instead of
> in the IOMMU TLB and the device always sets the translated bit for PASID.
> One example of those devices are AMD graphic devices that always have ACS
> or ATS enabled together with PASID.

this should be made clear that ATS alone doesn't imply that translated
bit is always set. It's just an optimization so the device may cache
translation for selective requests. Only combining with PRI to
support SVA has such implication.

> + * @flags: device-specific flags
> + *   - PCI_PASID_XLATED_REQ_ONLY: The PCI device only issues PASID
> + *                                memory requests of translated type.

this reads like the device even doesn't issue non-PASID requests.

It is clearer to be "The PCI device always use translated type for all
PASID memory requests".

Otherwise looks good to me:

Reviewed-by: Kevin Tian <kevin.tian@...el.com>