From: Alex Williamson <alex.williamson@redhat.com>
To: "Raj, Ashok" <ashok.raj@intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>, Joerg Roedel <joro@8bytes.org>,
"Tian, Kevin" <kevin.tian@intel.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
David Gibson <david@gibson.dropbear.id.au>,
Jason Wang <jasowang@redhat.com>,
"parav@mellanox.com" <parav@mellanox.com>,
"Enrico Weigelt, metux IT consult" <lkml@metux.net>,
Paolo Bonzini <pbonzini@redhat.com>,
Shenming Lu <lushenming@huawei.com>,
Eric Auger <eric.auger@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
"Liu, Yi L" <yi.l.liu@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
"Jiang, Dave" <dave.jiang@intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
Robin Murphy <robin.murphy@arm.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
David Woodhouse <dwmw2@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: Plan for /dev/ioasid RFC v2
Date: Fri, 18 Jun 2021 09:51:57 -0600 [thread overview]
Message-ID: <20210618095157.131eb309.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210618153735.GA37688@otc-nc-03>
On Fri, 18 Jun 2021 08:37:35 -0700
"Raj, Ashok" <ashok.raj@intel.com> wrote:
> On Fri, Jun 18, 2021 at 12:15:06PM -0300, Jason Gunthorpe wrote:
> > On Fri, Jun 18, 2021 at 03:47:51PM +0200, Joerg Roedel wrote:
> > > Hi Kevin,
> > >
> > > On Thu, Jun 17, 2021 at 07:31:03AM +0000, Tian, Kevin wrote:
> > > > Now let's talk about the new IOMMU behavior:
> > > >
> > > > - A device is blocked from doing DMA to any resource outside of
> > > > its group when it's probed by the IOMMU driver. This could be a
> > > > special state w/o attaching to any domain, or a new special domain
> > > > type which differentiates it from existing domain types (identity,
> > > > dma, or unmanged). Actually existing code already includes a
> > > > IOMMU_DOMAIN_BLOCKED type but nobody uses it.
> > >
> > > There is a reason for the default domain to exist: Devices which require
> > > RMRR mappings to be present. You can't just block all DMA from devices
> > > until a driver takes over, we put much effort into making sure there is
> > > not even a small window in time where RMRR regions (unity mapped regions
> > > on AMD) are not mapped.
> >
> > Yes, I think the DMA blocking can only start around/after a VFIO type
> > driver has probed() and bound to a device in the group, not much
> > different from today.
>
> Does this mean when a device has a required "RMRR" that requires a unity
> mapping we block assigning those devices to guests? I remember we had some
> restriction but there was a need to go around it at some point in time.
>
> - Either we disallow assigning devices with RMRR
> - Break that unity map when the device is probed and after which any RMRR
> access from device will fault.
We currently disallow assignment of RMRR encumbered devices except for
the known cases of USB and IGD. In the general case, an RMRR imposes
a requirement on the host system to maintain ranges of identity mapping
that is incompatible with userspace ownership of the device and IOVA
address space. AFAICT, nothing changes in the /dev/iommu model that
would make it safe to entrust userspace with RMRR encumbered devices.
Thanks,
Alex
WARNING: multiple messages have this Message-ID (diff)
From: Alex Williamson <alex.williamson@redhat.com>
To: "Raj, Ashok" <ashok.raj@intel.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Jason Wang <jasowang@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
"Jiang, Dave" <dave.jiang@intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Jason Gunthorpe <jgg@nvidia.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
"parav@mellanox.com" <parav@mellanox.com>,
"Enrico Weigelt, metux IT consult" <lkml@metux.net>,
David Gibson <david@gibson.dropbear.id.au>,
Robin Murphy <robin.murphy@arm.com>,
LKML <linux-kernel@vger.kernel.org>,
Shenming Lu <lushenming@huawei.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
Paolo Bonzini <pbonzini@redhat.com>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: Plan for /dev/ioasid RFC v2
Date: Fri, 18 Jun 2021 09:51:57 -0600 [thread overview]
Message-ID: <20210618095157.131eb309.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210618153735.GA37688@otc-nc-03>
On Fri, 18 Jun 2021 08:37:35 -0700
"Raj, Ashok" <ashok.raj@intel.com> wrote:
> On Fri, Jun 18, 2021 at 12:15:06PM -0300, Jason Gunthorpe wrote:
> > On Fri, Jun 18, 2021 at 03:47:51PM +0200, Joerg Roedel wrote:
> > > Hi Kevin,
> > >
> > > On Thu, Jun 17, 2021 at 07:31:03AM +0000, Tian, Kevin wrote:
> > > > Now let's talk about the new IOMMU behavior:
> > > >
> > > > - A device is blocked from doing DMA to any resource outside of
> > > > its group when it's probed by the IOMMU driver. This could be a
> > > > special state w/o attaching to any domain, or a new special domain
> > > > type which differentiates it from existing domain types (identity,
> > > > dma, or unmanged). Actually existing code already includes a
> > > > IOMMU_DOMAIN_BLOCKED type but nobody uses it.
> > >
> > > There is a reason for the default domain to exist: Devices which require
> > > RMRR mappings to be present. You can't just block all DMA from devices
> > > until a driver takes over, we put much effort into making sure there is
> > > not even a small window in time where RMRR regions (unity mapped regions
> > > on AMD) are not mapped.
> >
> > Yes, I think the DMA blocking can only start around/after a VFIO type
> > driver has probed() and bound to a device in the group, not much
> > different from today.
>
> Does this mean when a device has a required "RMRR" that requires a unity
> mapping we block assigning those devices to guests? I remember we had some
> restriction but there was a need to go around it at some point in time.
>
> - Either we disallow assigning devices with RMRR
> - Break that unity map when the device is probed and after which any RMRR
> access from device will fault.
We currently disallow assignment of RMRR encumbered devices except for
the known cases of USB and IGD. In the general case, an RMRR imposes
a requirement on the host system to maintain ranges of identity mapping
that is incompatible with userspace ownership of the device and IOVA
address space. AFAICT, nothing changes in the /dev/iommu model that
would make it safe to entrust userspace with RMRR encumbered devices.
Thanks,
Alex
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-06-18 15:52 UTC|newest]
Thread overview: 162+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-07 2:58 Plan for /dev/ioasid RFC v2 Tian, Kevin
2021-06-07 2:58 ` Tian, Kevin
2021-06-09 8:14 ` Eric Auger
2021-06-09 8:14 ` Eric Auger
2021-06-09 9:37 ` Tian, Kevin
2021-06-09 9:37 ` Tian, Kevin
2021-06-09 10:14 ` Eric Auger
2021-06-09 10:14 ` Eric Auger
2021-06-09 9:01 ` Leon Romanovsky
2021-06-09 9:01 ` Leon Romanovsky
2021-06-09 9:43 ` Tian, Kevin
2021-06-09 9:43 ` Tian, Kevin
2021-06-09 12:24 ` Joerg Roedel
2021-06-09 12:24 ` Joerg Roedel
2021-06-09 12:39 ` Jason Gunthorpe
2021-06-09 12:39 ` Jason Gunthorpe
2021-06-09 13:32 ` Joerg Roedel
2021-06-09 13:32 ` Joerg Roedel
2021-06-09 15:00 ` Jason Gunthorpe
2021-06-09 15:00 ` Jason Gunthorpe
2021-06-09 15:51 ` Joerg Roedel
2021-06-09 15:51 ` Joerg Roedel
2021-06-09 16:15 ` Alex Williamson
2021-06-09 16:15 ` Alex Williamson
2021-06-09 16:27 ` Alex Williamson
2021-06-09 16:27 ` Alex Williamson
2021-06-09 18:49 ` Jason Gunthorpe
2021-06-09 18:49 ` Jason Gunthorpe
2021-06-10 15:38 ` Alex Williamson
2021-06-10 15:38 ` Alex Williamson
2021-06-11 0:58 ` Tian, Kevin
2021-06-11 0:58 ` Tian, Kevin
2021-06-11 21:38 ` Alex Williamson
2021-06-11 21:38 ` Alex Williamson
2021-06-14 3:09 ` Tian, Kevin
2021-06-14 3:09 ` Tian, Kevin
2021-06-14 3:22 ` Alex Williamson
2021-06-14 3:22 ` Alex Williamson
2021-06-15 1:05 ` Tian, Kevin
2021-06-15 1:05 ` Tian, Kevin
2021-06-14 13:38 ` Jason Gunthorpe
2021-06-14 13:38 ` Jason Gunthorpe
2021-06-15 1:21 ` Tian, Kevin
2021-06-15 1:21 ` Tian, Kevin
2021-06-15 16:56 ` Alex Williamson
2021-06-15 16:56 ` Alex Williamson
2021-06-16 6:53 ` Tian, Kevin
2021-06-16 6:53 ` Tian, Kevin
2021-06-24 4:50 ` David Gibson
2021-06-24 4:50 ` David Gibson
2021-06-11 16:45 ` Jason Gunthorpe
2021-06-11 16:45 ` Jason Gunthorpe
2021-06-11 19:38 ` Alex Williamson
2021-06-11 19:38 ` Alex Williamson
2021-06-12 1:28 ` Jason Gunthorpe
2021-06-12 1:28 ` Jason Gunthorpe
2021-06-12 16:57 ` Alex Williamson
2021-06-12 16:57 ` Alex Williamson
2021-06-14 14:07 ` Jason Gunthorpe
2021-06-14 14:07 ` Jason Gunthorpe
2021-06-14 16:28 ` Alex Williamson
2021-06-14 16:28 ` Alex Williamson
2021-06-14 19:40 ` Jason Gunthorpe
2021-06-14 19:40 ` Jason Gunthorpe
2021-06-15 2:31 ` Tian, Kevin
2021-06-15 2:31 ` Tian, Kevin
2021-06-15 16:12 ` Alex Williamson
2021-06-15 16:12 ` Alex Williamson
2021-06-16 6:43 ` Tian, Kevin
2021-06-16 6:43 ` Tian, Kevin
2021-06-16 19:39 ` Alex Williamson
2021-06-16 19:39 ` Alex Williamson
2021-06-17 3:39 ` Liu Yi L
2021-06-17 3:39 ` Liu Yi L
2021-06-17 7:31 ` Tian, Kevin
2021-06-17 7:31 ` Tian, Kevin
2021-06-17 21:14 ` Alex Williamson
2021-06-17 21:14 ` Alex Williamson
2021-06-18 0:19 ` Jason Gunthorpe
2021-06-18 0:19 ` Jason Gunthorpe
2021-06-18 16:57 ` Tian, Kevin
2021-06-18 16:57 ` Tian, Kevin
2021-06-18 18:23 ` Jason Gunthorpe
2021-06-18 18:23 ` Jason Gunthorpe
2021-06-25 10:27 ` Tian, Kevin
2021-06-25 10:27 ` Tian, Kevin
2021-06-25 14:36 ` Jason Gunthorpe
2021-06-25 14:36 ` Jason Gunthorpe
2021-06-28 1:09 ` Tian, Kevin
2021-06-28 1:09 ` Tian, Kevin
2021-06-28 22:31 ` Alex Williamson
2021-06-28 22:31 ` Alex Williamson
2021-06-28 22:48 ` Jason Gunthorpe
2021-06-28 22:48 ` Jason Gunthorpe
2021-06-28 23:09 ` Alex Williamson
2021-06-28 23:09 ` Alex Williamson
2021-06-28 23:13 ` Jason Gunthorpe
2021-06-28 23:13 ` Jason Gunthorpe
2021-06-29 0:26 ` Tian, Kevin
2021-06-29 0:26 ` Tian, Kevin
2021-06-29 0:28 ` Tian, Kevin
2021-06-29 0:28 ` Tian, Kevin
2021-06-29 0:43 ` Tian, Kevin
2021-06-29 0:43 ` Tian, Kevin
2021-06-28 2:03 ` Tian, Kevin
2021-06-28 2:03 ` Tian, Kevin
2021-06-28 14:41 ` Jason Gunthorpe
2021-06-28 14:41 ` Jason Gunthorpe
2021-06-28 6:45 ` Tian, Kevin
2021-06-28 6:45 ` Tian, Kevin
2021-06-28 16:26 ` Jason Gunthorpe
2021-06-28 16:26 ` Jason Gunthorpe
2021-06-24 4:26 ` David Gibson
2021-06-24 4:26 ` David Gibson
2021-06-24 5:59 ` Tian, Kevin
2021-06-24 5:59 ` Tian, Kevin
2021-06-24 12:22 ` Lu Baolu
2021-06-24 12:22 ` Lu Baolu
2021-06-24 4:23 ` David Gibson
2021-06-24 4:23 ` David Gibson
2021-06-18 0:52 ` Jason Gunthorpe
2021-06-18 0:52 ` Jason Gunthorpe
2021-06-18 13:47 ` Joerg Roedel
2021-06-18 13:47 ` Joerg Roedel
2021-06-18 15:15 ` Jason Gunthorpe
2021-06-18 15:15 ` Jason Gunthorpe
2021-06-18 15:37 ` Raj, Ashok
2021-06-18 15:37 ` Raj, Ashok
2021-06-18 15:51 ` Alex Williamson [this message]
2021-06-18 15:51 ` Alex Williamson
2021-06-24 4:29 ` David Gibson
2021-06-24 4:29 ` David Gibson
2021-06-24 11:56 ` Jason Gunthorpe
2021-06-24 11:56 ` Jason Gunthorpe
2021-06-18 0:10 ` Jason Gunthorpe
2021-06-18 0:10 ` Jason Gunthorpe
2021-06-17 5:29 ` David Gibson
2021-06-17 5:29 ` David Gibson
2021-06-17 5:02 ` David Gibson
2021-06-17 5:02 ` David Gibson
2021-06-17 23:04 ` Jason Gunthorpe
2021-06-17 23:04 ` Jason Gunthorpe
2021-06-24 4:37 ` David Gibson
2021-06-24 4:37 ` David Gibson
2021-06-24 11:57 ` Jason Gunthorpe
2021-06-24 11:57 ` Jason Gunthorpe
2021-06-10 5:50 ` Lu Baolu
2021-06-10 5:50 ` Lu Baolu
2021-06-17 5:22 ` David Gibson
2021-06-17 5:22 ` David Gibson
2021-06-18 5:21 ` Lu Baolu
2021-06-18 5:21 ` Lu Baolu
2021-06-24 4:03 ` David Gibson
2021-06-24 4:03 ` David Gibson
2021-06-24 13:42 ` Lu Baolu
2021-06-24 13:42 ` Lu Baolu
2021-06-17 4:45 ` David Gibson
2021-06-17 4:45 ` David Gibson
2021-06-17 23:10 ` Jason Gunthorpe
2021-06-17 23:10 ` Jason Gunthorpe
2021-06-24 4:07 ` David Gibson
2021-06-24 4:07 ` David Gibson
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