linux-kernel - RE: [PATCH v8 5/9] hisi_acc_vfio_pci: Restrict access to VF dev BAR2 migration region

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Message-ID: <BN9PR11MB527681F9F6B0906596A77A178C099@BN9PR11MB5276.namprd11.prod.outlook.com>
Date:   Tue, 8 Mar 2022 06:23:29 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "mgurtovoy@...dia.com" <mgurtovoy@...dia.com>,
        "yishaih@...dia.com" <yishaih@...dia.com>,
        "linuxarm@...wei.com" <linuxarm@...wei.com>,
        "liulongfang@...wei.com" <liulongfang@...wei.com>,
        "prime.zeng@...ilicon.com" <prime.zeng@...ilicon.com>,
        "jonathan.cameron@...wei.com" <jonathan.cameron@...wei.com>,
        "wangzhou1@...ilicon.com" <wangzhou1@...ilicon.com>
Subject: RE: [PATCH v8 5/9] hisi_acc_vfio_pci: Restrict access to VF dev BAR2
 migration region

Hi, Shameer,

> From: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> Sent: Friday, March 4, 2022 7:01 AM
> 
> HiSilicon ACC VF device BAR2 region consists of both functional
> register space and migration control register space. From a
> security point of view, it's not advisable to export the migration
> control region to Guest.
> 
> Hence, introduce a separate struct vfio_device_ops for migration
> support which will override the ioctl/read/write/mmap methods to
> hide the migration region and limit the access only to the
> functional register space.
> 
> This will be used in subsequent patches when we add migration
> support to the driver.

As a security concern the migration control region should be always
disabled regardless of whether migration support is added to the
driver for such device... It sounds like we should first fix this security
hole for acc device assignment and then add the migration support
atop (at least organize the series in this way).

Thanks
Kevin