From: Thomas Gleixner <tglx@linutronix.de>
To: "Raj\, Ashok" <ashok.raj@intel.com>,
Christoph Hellwig <hch@infradead.org>
Cc: David Woodhouse <dwmw2@infradead.org>,
Jason Gunthorpe <jgg@nvidia.com>,
Dan Williams <dan.j.williams@intel.com>, "Tian\,
Kevin" <kevin.tian@intel.com>, "Jiang\,
Dave" <dave.jiang@intel.com>, Bjorn Helgaas <helgaas@kernel.org>,
"vkoul\@kernel.org" <vkoul@kernel.org>, "Dey\,
Megha" <megha.dey@intel.com>, "maz\@kernel.org" <maz@kernel.org>,
"bhelgaas\@google.com" <bhelgaas@google.com>,
"alex.williamson\@redhat.com" <alex.williamson@redhat.com>, "Pan\,
Jacob jun" <jacob.jun.pan@intel.com>, "Liu\,
Yi L" <yi.l.liu@intel.com>, "Lu\, Baolu" <baolu.lu@intel.com>,
"Kumar\, Sanjay K" <sanjay.k.kumar@intel.com>, "Luck\,
Tony" <tony.luck@intel.com>,
"jing.lin\@intel.com" <jing.lin@intel.com>,
"kwankhede\@nvidia.com" <kwankhede@nvidia.com>,
"eric.auger\@redhat.com" <eric.auger@redhat.com>,
"parav\@mellanox.com" <parav@mellanox.com>,
"rafael\@kernel.org" <rafael@kernel.org>,
"netanelg\@mellanox.com" <netanelg@mellanox.com>,
"shahafs\@mellanox.com" <shahafs@mellanox.com>,
"yan.y.zhao\@linux.intel.com" <yan.y.zhao@linux.intel.com>,
"pbonzini\@redhat.com" <pbonzini@redhat.com>, "Ortiz\,
Samuel" <samuel.ortiz@intel.com>, "Hossain\,
Mona" <mona.hossain@intel.com>,
"dmaengine\@vger.kernel.org" <dmaengine@vger.kernel.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci\@vger.kernel.org" <linux-pci@vger.kernel.org>,
"kvm\@vger.kernel.org" <kvm@vger.kernel.org>,
Ashok Raj <ashok.raj@intel.com>
Subject: Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection
Date: Wed, 11 Nov 2020 23:27:28 +0100 [thread overview]
Message-ID: <87k0uro7fz.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201111160922.GA83266@otc-nc-03>
On Wed, Nov 11 2020 at 08:09, Ashok Raj wrote:
> On Wed, Nov 11, 2020 at 03:41:59PM +0000, Christoph Hellwig wrote:
>> On Sun, Nov 08, 2020 at 07:36:34PM +0000, David Woodhouse wrote:
>> > So it does look like we're going to need a hypercall interface to
>> > compose an MSI message on behalf of the guest, for IMS to use. In fact
>> > PCI devices assigned to a guest could use that too, and then we'd only
>> > need to trap-and-remap any attempt to write a Compatibility Format MSI
>> > to the device's MSI table, while letting Remappable Format messages get
>> > written directly.
>> >
>> > We'd also need a way for an OS running on bare metal to *know* that
>> > it's on bare metal and can just compose MSI messages for itself. Since
>> > we do expect bare metal to have an IOMMU, perhaps that is just a
>> > feature flag on the IOMMU?
>>
>> Have the platform firmware advertise if it needs native or virtualized
>> IMS handling. If it advertises neither don't support IMS?
>
> The platform hint can be easily accomplished via DMAR table flags. We could
> have an IMS_OPTOUT(similart to x2apic optout flag) flag, when 0 its native
> and IMS is supported.
>
> When vIOMMU is presented to guest, virtual DMAR table will have this flag
> set to 1. Indicates to GuestOS, native IMS isn't supported.
These opt-out bits suck by definition. It comes all back to the fact
that the whole virt thing didn't have a hardware defined way to tell
that the OS runs in a VM and not on bare metal. It wouldn't have been
rocket science to do so.
And because that does not exist, we need magic opt-out bits for every
other piece of functionality which gets added. Can we please stop this
and provide a well defined way to tell the OS whether it runs on bare
metal or not?
The point is that you really want opt-in bits so that decisions come
down to
if (!virt || virt->supports_X)
which is the obvious sane and safe logic. But sure, why am I asking for
sane and safe in the context of virtualization?
Thanks,
tglx
next prev parent reply other threads:[~2020-11-12 2:05 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-30 18:50 [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Dave Jiang
2020-10-30 18:50 ` [PATCH v4 01/17] irqchip: Add IMS (Interrupt Message Store) driver Dave Jiang
2020-10-30 22:01 ` Thomas Gleixner
2020-10-30 18:51 ` [PATCH v4 02/17] iommu/vt-d: Add DEV-MSI support Dave Jiang
2020-10-30 20:31 ` Thomas Gleixner
2020-10-30 20:52 ` Dave Jiang
2020-10-30 18:51 ` [PATCH v4 03/17] dmaengine: idxd: add theory of operation documentation for idxd mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 04/17] dmaengine: idxd: add support for readonly config devices Dave Jiang
2020-10-30 18:51 ` [PATCH v4 05/17] dmaengine: idxd: add interrupt handle request support Dave Jiang
2020-10-30 18:51 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Dave Jiang
2020-10-30 19:51 ` Bjorn Helgaas
2020-10-30 21:20 ` Dave Jiang
2020-10-30 21:50 ` Bjorn Helgaas
2020-10-30 22:45 ` Jason Gunthorpe
2020-10-30 22:49 ` Dave Jiang
2020-11-02 13:21 ` Jason Gunthorpe
2020-11-03 2:49 ` Tian, Kevin
2020-11-03 12:43 ` Jason Gunthorpe
2020-11-04 3:41 ` Tian, Kevin
2020-11-04 12:40 ` Jason Gunthorpe
2020-11-04 13:34 ` Tian, Kevin
2020-11-04 13:54 ` Jason Gunthorpe
2020-11-06 9:48 ` Tian, Kevin
2020-11-06 13:14 ` Jason Gunthorpe
2020-11-06 16:48 ` Raj, Ashok
2020-11-06 17:51 ` Jason Gunthorpe
2020-11-06 23:47 ` Dan Williams
2020-11-07 0:12 ` Jason Gunthorpe
2020-11-07 1:42 ` Dan Williams
2020-11-08 18:11 ` Raj, Ashok
2020-11-08 18:34 ` David Woodhouse
2020-11-08 23:25 ` Raj, Ashok
2020-11-10 14:19 ` Raj, Ashok
2020-11-10 14:41 ` David Woodhouse
2020-11-08 23:41 ` Jason Gunthorpe
2020-11-09 0:05 ` Raj, Ashok
2020-11-08 18:47 ` Thomas Gleixner
2020-11-08 19:36 ` David Woodhouse
2020-11-08 22:47 ` Thomas Gleixner
2020-11-08 23:29 ` Jason Gunthorpe
2020-11-11 15:41 ` Christoph Hellwig
2020-11-11 16:09 ` Raj, Ashok
2020-11-11 22:27 ` Thomas Gleixner [this message]
2020-11-11 23:03 ` Raj, Ashok
2020-11-12 1:13 ` Thomas Gleixner
2020-11-12 13:10 ` Jason Gunthorpe
2020-11-08 23:23 ` Jason Gunthorpe
2020-11-08 23:36 ` Raj, Ashok
2020-11-09 7:37 ` Tian, Kevin
2020-11-09 16:46 ` Jason Gunthorpe
2020-11-08 23:58 ` Raj, Ashok
2020-11-09 7:59 ` Tian, Kevin
2020-11-09 11:21 ` Thomas Gleixner
2020-11-09 17:30 ` Jason Gunthorpe
2020-11-09 22:40 ` Raj, Ashok
2020-11-09 22:42 ` Thomas Gleixner
2020-11-10 5:14 ` Raj, Ashok
2020-11-10 10:27 ` Thomas Gleixner
2020-11-10 14:13 ` Raj, Ashok
2020-11-10 14:23 ` Jason Gunthorpe
2020-11-11 2:17 ` Tian, Kevin
2020-11-12 13:46 ` Jason Gunthorpe
2020-11-11 7:14 ` Tian, Kevin
2020-11-12 19:32 ` Konrad Rzeszutek Wilk
2020-11-12 22:42 ` Thomas Gleixner
2020-11-13 2:42 ` Tian, Kevin
2020-11-13 12:57 ` Jason Gunthorpe
2020-11-13 13:32 ` Thomas Gleixner
2020-11-13 16:12 ` Luck, Tony
2020-11-13 17:38 ` Raj, Ashok
2020-11-14 10:34 ` Christoph Hellwig
2020-11-14 21:18 ` Raj, Ashok
2020-11-15 11:26 ` Thomas Gleixner
2020-11-15 19:31 ` Raj, Ashok
2020-11-15 22:11 ` Thomas Gleixner
2020-11-16 0:22 ` Raj, Ashok
2020-11-16 7:31 ` Tian, Kevin
2020-11-16 15:46 ` Jason Gunthorpe
2020-11-16 17:56 ` Thomas Gleixner
2020-11-16 18:02 ` Jason Gunthorpe
2020-11-16 20:37 ` Thomas Gleixner
2020-11-16 23:51 ` Tian, Kevin
2020-11-17 9:21 ` Thomas Gleixner
2020-11-16 8:25 ` Christoph Hellwig
2020-11-10 14:19 ` Jason Gunthorpe
2020-11-11 2:35 ` Tian, Kevin
2020-11-08 21:18 ` Thomas Gleixner
2020-11-08 22:09 ` David Woodhouse
2020-11-08 22:52 ` Thomas Gleixner
2020-11-07 0:32 ` Thomas Gleixner
2020-11-09 5:25 ` Tian, Kevin
2020-10-30 18:51 ` [PATCH v4 07/17] dmaengine: idxd: add IMS support in base driver Dave Jiang
2020-10-30 18:51 ` [PATCH v4 08/17] dmaengine: idxd: add device support functions in prep for mdev Dave Jiang
2020-10-30 18:51 ` [PATCH v4 09/17] dmaengine: idxd: add basic mdev registration and helper functions Dave Jiang
2020-10-30 18:51 ` [PATCH v4 10/17] dmaengine: idxd: add emulation rw routines Dave Jiang
2020-10-30 18:52 ` [PATCH v4 11/17] dmaengine: idxd: prep for virtual device commands Dave Jiang
2020-10-30 18:52 ` [PATCH v4 12/17] dmaengine: idxd: virtual device commands emulation Dave Jiang
2020-10-30 18:52 ` [PATCH v4 13/17] dmaengine: idxd: ims setup for the vdcm Dave Jiang
2020-10-30 21:26 ` Thomas Gleixner
2020-10-30 18:52 ` [PATCH v4 14/17] dmaengine: idxd: add mdev type as a new wq type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 15/17] dmaengine: idxd: add dedicated wq mdev type Dave Jiang
2020-10-30 18:52 ` [PATCH v4 16/17] dmaengine: idxd: add new wq state for mdev Dave Jiang
2020-10-30 18:52 ` [PATCH v4 17/17] dmaengine: idxd: add error notification from host driver to mediated device Dave Jiang
2020-10-30 18:58 ` [PATCH v4 00/17] Add VFIO mediated device support and DEV-MSI support for the idxd driver Jason Gunthorpe
2020-10-30 19:13 ` Dave Jiang
2020-10-30 19:17 ` Jason Gunthorpe
2020-10-30 19:23 ` Raj, Ashok
2020-10-30 19:30 ` Jason Gunthorpe
2020-10-30 20:43 ` Raj, Ashok
2020-10-30 22:54 ` Jason Gunthorpe
2020-10-31 2:50 ` Thomas Gleixner
2020-10-31 23:53 ` Raj, Ashok
2020-11-02 13:20 ` Jason Gunthorpe
2020-11-02 16:20 ` Raj, Ashok
2020-11-02 17:19 ` Jason Gunthorpe
2020-11-02 18:18 ` Dave Jiang
2020-11-02 18:26 ` Jason Gunthorpe
2020-11-02 18:38 ` Dan Williams
2020-11-02 18:51 ` Jason Gunthorpe
2020-11-02 19:26 ` Dan Williams
2020-10-30 20:48 ` Thomas Gleixner
2020-10-30 20:59 ` Dave Jiang
2020-10-30 22:10 ` Thomas Gleixner
[not found] <draft-875z6ekcj5.fsf@nanos.tec.linutronix.de>
2020-11-09 14:08 ` [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Thomas Gleixner
2020-11-09 18:10 ` Raj, Ashok
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