linux-kernel - Re: [patch 21/32] NTB/msi: Convert to msi_on_each

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20211210123028.GD6385@nvidia.com>
Date:   Fri, 10 Dec 2021 08:30:28 -0400
From:   Jason Gunthorpe <jgg@...dia.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        "Dey, Megha" <megha.dey@...el.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jon Mason <jdmason@...zu.us>, Allen Hubbe <allenbh@...il.com>,
        "linux-ntb@...glegroups.com" <linux-ntb@...glegroups.com>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        "x86@...nel.org" <x86@...nel.org>, Joerg Roedel <jroedel@...e.de>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
Subject: Re: [patch 21/32] NTB/msi: Convert to msi_on_each_desc()

On Fri, Dec 10, 2021 at 07:36:12AM +0000, Tian, Kevin wrote:

> /*
>  * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped
>  * which allows direct access to non-MSIX registers which happened to be within
>  * the same system page.
>  *
>  * Even though the userspace gets direct access to the MSIX data, the existing
>  * VFIO_DEVICE_SET_IRQS interface must still be used for MSIX configuration.
     ^^^^^^^^^^^^^^^^^^^^^

It is this I think we don't want, there should be no hypervisor
involvment on installing the addr/data pair

Guessing by what I saw in PPC there is a hypercall to install a MSI
and the guest never touches the page even though it is
mapped. Presumably there is some IR like thing making this secured

PPC has the same basic problem, I think they have a hypercall to
install a MSI, not a hypercall to provision a generic addr/data pair.

Jason