From: Marc Zyngier <maz@kernel.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Nipun Gupta <nipun.gupta@amd.com>,
robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
gregkh@linuxfoundation.org, rafael@kernel.org,
eric.auger@redhat.com, alex.williamson@redhat.com,
cohuck@redhat.com, puneet.gupta@amd.com,
song.bao.hua@hisilicon.com, mchehab+huawei@kernel.org,
f.fainelli@gmail.com, jeffrey.l.hugo@gmail.com,
saravanak@google.com, Michael.Srba@seznam.cz, mani@kernel.org,
yishaih@nvidia.com, robin.murphy@arm.com, will@kernel.org,
joro@8bytes.org, masahiroy@kernel.org, ndesaulniers@google.com,
linux-arm-kernel@lists.infradead.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org, kvm@vger.kernel.org,
okaya@kernel.org, harpreet.anand@amd.com, nikhil.agarwal@amd.com,
michal.simek@amd.com, aleksandar.radovanovic@amd.com,
git@amd.com
Subject: Re: [RFC PATCH v3 4/7] bus/cdx: add cdx-MSI domain with gic-its domain as parent
Date: Wed, 07 Sep 2022 12:17:28 +0100 [thread overview]
Message-ID: <87leqvv3g7.wl-maz@kernel.org> (raw)
In-Reply-To: <YxeBCsA32jnwMjSj@nvidia.com>
On Tue, 06 Sep 2022 18:19:06 +0100,
Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> On Tue, Sep 06, 2022 at 07:17:58PM +0530, Nipun Gupta wrote:
>
> > +static void cdx_msi_write_msg(struct irq_data *irq_data,
> > + struct msi_msg *msg)
> > +{
> > + /*
> > + * Do nothing as CDX devices have these pre-populated
> > + * in the hardware itself.
> > + */
> > +}
>
> Huh?
>
> There is no way it can be pre-populated, the addr/data pair,
> especially on ARM, is completely under SW control.
There is nothing in the GIC spec that says that.
> There is some commonly used IOVA base in Linux for the ITS page, but
> no HW should hardwire that.
That's not strictly true. It really depends on how this block is
integrated, and there is a number of existing blocks that know *in HW*
how to signal an LPI.
See, as the canonical example, how the mbigen driver doesn't need to
know about the address of GITS_TRANSLATER.
Yes, this messes with translation (the access is downstream of the
SMMU) if you relied on it to have some isolation, and it has a "black
hole" effect as nobody can have an IOVA that overlaps with the
physical address of the GITS_TRANSLATER register.
But is it illegal as per the architecture? No. It's just stupid.
M.
--
Without deviation from the norm, progress is not possible.
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Nipun Gupta <nipun.gupta@amd.com>,
robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
gregkh@linuxfoundation.org, rafael@kernel.org,
eric.auger@redhat.com, alex.williamson@redhat.com,
cohuck@redhat.com, puneet.gupta@amd.com,
song.bao.hua@hisilicon.com, mchehab+huawei@kernel.org,
f.fainelli@gmail.com, jeffrey.l.hugo@gmail.com,
saravanak@google.com, Michael.Srba@seznam.cz, mani@kernel.org,
yishaih@nvidia.com, robin.murphy@arm.com, will@kernel.org,
joro@8bytes.org, masahiroy@kernel.org, ndesaulniers@google.com,
linux-arm-kernel@lists.infradead.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
devicetree@vger.kernel.org, kvm@vger.kernel.org,
okaya@kernel.org, harpreet.anand@amd.com, nikhil.agarwal@amd.com,
michal.simek@amd.com, aleksandar.radovanovic@amd.com,
git@amd.com
Subject: Re: [RFC PATCH v3 4/7] bus/cdx: add cdx-MSI domain with gic-its domain as parent
Date: Wed, 07 Sep 2022 12:17:28 +0100 [thread overview]
Message-ID: <87leqvv3g7.wl-maz@kernel.org> (raw)
In-Reply-To: <YxeBCsA32jnwMjSj@nvidia.com>
On Tue, 06 Sep 2022 18:19:06 +0100,
Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> On Tue, Sep 06, 2022 at 07:17:58PM +0530, Nipun Gupta wrote:
>
> > +static void cdx_msi_write_msg(struct irq_data *irq_data,
> > + struct msi_msg *msg)
> > +{
> > + /*
> > + * Do nothing as CDX devices have these pre-populated
> > + * in the hardware itself.
> > + */
> > +}
>
> Huh?
>
> There is no way it can be pre-populated, the addr/data pair,
> especially on ARM, is completely under SW control.
There is nothing in the GIC spec that says that.
> There is some commonly used IOVA base in Linux for the ITS page, but
> no HW should hardwire that.
That's not strictly true. It really depends on how this block is
integrated, and there is a number of existing blocks that know *in HW*
how to signal an LPI.
See, as the canonical example, how the mbigen driver doesn't need to
know about the address of GITS_TRANSLATER.
Yes, this messes with translation (the access is downstream of the
SMMU) if you relied on it to have some isolation, and it has a "black
hole" effect as nobody can have an IOVA that overlaps with the
physical address of the GITS_TRANSLATER register.
But is it illegal as per the architecture? No. It's just stupid.
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-09-07 11:17 UTC|newest]
Thread overview: 198+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-03 12:26 [RFC PATCH 0/2] add support for CDX bus MSI domain Nipun Gupta
2022-08-03 12:26 ` Nipun Gupta
2022-08-03 12:26 ` [RFC PATCH 1/2] irqchip: cdx-bus: add cdx-MSI domain with gic-its domain as parent Nipun Gupta
2022-08-03 12:26 ` Nipun Gupta
2022-08-03 12:33 ` Greg KH
2022-08-03 12:33 ` Greg KH
2022-08-03 12:37 ` Gupta, Nipun
2022-08-03 12:37 ` Gupta, Nipun
2022-08-04 8:49 ` Marc Zyngier
2022-08-04 8:49 ` Marc Zyngier
2022-08-04 9:18 ` Gupta, Nipun
2022-08-04 9:18 ` Gupta, Nipun
2022-08-04 10:38 ` Marc Zyngier
2022-08-04 12:11 ` Gupta, Nipun
2022-08-04 12:11 ` Gupta, Nipun
2022-08-03 12:26 ` [RFC PATCH 2/2] driver core: add compatible string in sysfs for platform devices Nipun Gupta
2022-08-03 12:26 ` Nipun Gupta
2022-08-03 12:31 ` Greg KH
2022-08-03 12:31 ` Greg KH
2022-08-03 12:46 ` Gupta, Nipun
2022-08-03 12:46 ` Gupta, Nipun
2022-08-03 14:16 ` [RFC PATCH 0/2] add support for CDX bus MSI domain Robin Murphy
2022-08-03 14:16 ` Robin Murphy
2022-08-04 4:23 ` Gupta, Nipun
2022-08-04 4:23 ` Gupta, Nipun
2022-08-17 16:00 ` Jason Gunthorpe
2022-08-17 16:00 ` Jason Gunthorpe
2022-08-17 15:05 ` [RFC PATCH v2 0/6] add support for CDX bus controller Nipun Gupta
2022-08-17 15:05 ` [RFC PATCH v2 1/6] Documentation: DT: Add entry for CDX controller Nipun Gupta
2022-08-18 9:54 ` Krzysztof Kozlowski
2022-08-18 9:59 ` Krzysztof Kozlowski
2022-09-05 14:05 ` Gupta, Nipun
2022-09-06 6:55 ` Krzysztof Kozlowski
2022-09-06 7:03 ` Gupta, Nipun
2022-09-06 7:20 ` Krzysztof Kozlowski
2022-08-17 15:05 ` [RFC PATCH v2 2/6] bus/cdx: add the cdx bus driver Nipun Gupta
2022-08-17 15:32 ` Greg KH
2022-08-17 15:46 ` Marc Zyngier
2022-08-22 13:21 ` Gupta, Nipun
2022-08-22 13:29 ` Greg KH
2022-08-24 8:50 ` Gupta, Nipun
2022-08-24 12:11 ` Greg KH
2022-08-24 23:31 ` Jason Gunthorpe
2022-08-25 18:38 ` Saravana Kannan
2022-08-25 19:57 ` Robin Murphy
2022-08-26 0:08 ` Jason Gunthorpe
2022-08-29 4:49 ` Gupta, Nipun
2022-08-29 4:49 ` Gupta, Nipun
2022-08-29 15:31 ` Jason Gunthorpe
2022-08-30 7:06 ` Gupta, Nipun
2022-08-30 11:25 ` Robin Murphy
2022-08-30 13:01 ` Jason Gunthorpe
2022-08-30 13:12 ` Gupta, Nipun
2022-08-17 15:05 ` [RFC PATCH v2 3/6] bus/cdx: add cdx-MSI domain with gic-its domain as parent Nipun Gupta
2022-08-17 15:33 ` Greg KH
2022-08-17 15:05 ` [RFC PATCH v2 4/6] bus/cdx: add rescan and reset support Nipun Gupta
2022-08-17 15:05 ` [RFC PATCH v2 5/6] vfio: platform: reset: add reset for cdx devices Nipun Gupta
2022-08-17 15:05 ` [RFC PATCH v2 6/6] driver core: add compatible string in sysfs for platform devices Nipun Gupta
2022-08-17 15:30 ` Greg KH
2022-08-17 16:04 ` Saravana Kannan
2022-09-05 13:54 ` Gupta, Nipun
2022-09-06 13:47 ` [RFC PATCH v3 0/7] add support for CDX bus Nipun Gupta
2022-09-06 13:47 ` Nipun Gupta
2022-09-06 13:47 ` [RFC PATCH v3 1/7] dt-bindings: bus: add CDX bus device tree bindings Nipun Gupta
2022-09-06 13:47 ` Nipun Gupta
2022-09-06 17:46 ` Rob Herring
2022-09-06 17:46 ` Rob Herring
2022-09-07 3:13 ` Gupta, Nipun
2022-09-07 3:13 ` Gupta, Nipun
2022-09-08 10:51 ` Krzysztof Kozlowski
2022-09-08 10:51 ` Krzysztof Kozlowski
2022-09-06 13:47 ` [RFC PATCH v3 2/7] bus/cdx: add the cdx bus driver Nipun Gupta
2022-09-06 13:47 ` Nipun Gupta
2022-09-07 0:32 ` Saravana Kannan
2022-09-07 0:32 ` Saravana Kannan
2022-09-07 3:21 ` Gupta, Nipun
2022-09-07 3:21 ` Gupta, Nipun
2022-09-07 18:06 ` Saravana Kannan
2022-09-07 18:06 ` Saravana Kannan
2022-09-07 12:32 ` Greg KH
2022-09-07 12:32 ` Greg KH
2022-09-08 13:29 ` Gupta, Nipun
2022-09-08 13:29 ` Gupta, Nipun
2022-09-06 13:47 ` [RFC PATCH v3 3/7] iommu/arm-smmu-v3: support ops registration for CDX bus Nipun Gupta
2022-09-06 13:47 ` Nipun Gupta
2022-09-07 0:10 ` Saravana Kannan
2022-09-07 0:10 ` Saravana Kannan
2022-09-07 3:17 ` Gupta, Nipun
2022-09-07 3:17 ` Gupta, Nipun
2022-09-07 8:27 ` Robin Murphy
2022-09-07 8:27 ` Robin Murphy
2022-09-07 18:24 ` Saravana Kannan
2022-09-07 18:24 ` Saravana Kannan
2022-09-07 20:40 ` Robin Murphy
2022-09-07 20:40 ` Robin Murphy
2022-09-08 0:14 ` Saravana Kannan
2022-09-08 0:14 ` Saravana Kannan
2022-09-06 13:47 ` [RFC PATCH v3 4/7] bus/cdx: add cdx-MSI domain with gic-its domain as parent Nipun Gupta
2022-09-06 13:47 ` Nipun Gupta
2022-09-06 17:19 ` Jason Gunthorpe
2022-09-06 17:19 ` Jason Gunthorpe
2022-09-07 11:17 ` Marc Zyngier [this message]
2022-09-07 11:17 ` Marc Zyngier
2022-09-07 11:33 ` Robin Murphy
2022-09-07 11:33 ` Robin Murphy
2022-09-07 12:14 ` Marc Zyngier
2022-09-07 12:14 ` Marc Zyngier
2022-09-07 11:35 ` Radovanovic, Aleksandar
2022-09-07 11:35 ` Radovanovic, Aleksandar
2022-09-07 12:32 ` Marc Zyngier
2022-09-07 13:18 ` Radovanovic, Aleksandar
2022-09-07 13:18 ` Radovanovic, Aleksandar
2022-09-08 8:08 ` Marc Zyngier
2022-09-08 9:51 ` Radovanovic, Aleksandar
2022-09-08 9:51 ` Radovanovic, Aleksandar
2022-09-08 11:49 ` Robin Murphy
2022-09-08 11:49 ` Robin Murphy
2022-09-08 14:18 ` Marc Zyngier
2022-09-07 13:18 ` Marc Zyngier
2022-09-07 13:18 ` Marc Zyngier
2022-09-08 14:13 ` Gupta, Nipun
2022-09-08 14:13 ` Gupta, Nipun
2022-09-08 14:29 ` Marc Zyngier
2022-09-09 6:32 ` Gupta, Nipun
2022-09-09 6:32 ` Gupta, Nipun
2022-10-12 10:04 ` Gupta, Nipun
2022-10-12 10:04 ` Gupta, Nipun
2022-10-12 10:34 ` Radovanovic, Aleksandar
2022-10-12 10:34 ` Radovanovic, Aleksandar
2022-10-12 13:02 ` Jason Gunthorpe
2022-10-12 13:02 ` Jason Gunthorpe
2022-10-12 13:37 ` Radovanovic, Aleksandar
2022-10-12 13:37 ` Radovanovic, Aleksandar
2022-10-12 14:38 ` Jason Gunthorpe
2022-10-12 14:38 ` Jason Gunthorpe
2022-10-12 15:09 ` Radovanovic, Aleksandar
2022-10-12 15:09 ` Radovanovic, Aleksandar
2022-10-13 12:43 ` Jason Gunthorpe
2022-10-13 12:43 ` Jason Gunthorpe
2022-10-14 11:18 ` Radovanovic, Aleksandar
2022-10-14 11:18 ` Radovanovic, Aleksandar
2022-10-14 11:54 ` gregkh
2022-10-14 11:54 ` gregkh
2022-10-14 12:13 ` Radovanovic, Aleksandar
2022-10-14 12:13 ` Radovanovic, Aleksandar
2022-10-14 13:46 ` gregkh
2022-10-14 13:46 ` gregkh
2022-10-14 13:58 ` Jason Gunthorpe
2022-10-14 13:58 ` Jason Gunthorpe
2022-09-06 13:47 ` [RFC PATCH v3 5/7] bus/cdx: add bus and device attributes Nipun Gupta
2022-09-06 13:47 ` Nipun Gupta
2022-09-06 13:48 ` [RFC PATCH v3 6/7] vfio/cdx: add support for CDX bus Nipun Gupta
2022-09-06 13:48 ` Nipun Gupta
2022-09-06 17:20 ` Jason Gunthorpe
2022-09-06 17:20 ` Jason Gunthorpe
2022-09-06 17:23 ` Gupta, Nipun
2022-09-06 17:23 ` Gupta, Nipun
2022-09-06 13:48 ` [RFC PATCH v3 7/7] vfio/cdx: add interrupt support Nipun Gupta
2022-09-06 13:48 ` Nipun Gupta
2022-10-14 4:40 ` [RFC PATCH v4 0/8] add support for CDX bus Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 4:40 ` [RFC PATCH v4 1/8] dt-bindings: bus: add CDX bus device tree bindings Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 14:17 ` Rob Herring
2022-10-14 14:17 ` Rob Herring
2022-10-17 10:18 ` Gupta, Nipun
2022-10-17 10:18 ` Gupta, Nipun
2022-10-14 4:40 ` [RFC PATCH v4 2/8] bus/cdx: add the cdx bus driver Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 7:15 ` Greg KH
2022-10-14 7:15 ` Greg KH
2022-10-14 8:12 ` Gupta, Nipun
2022-10-14 8:12 ` Gupta, Nipun
2022-10-14 7:18 ` Greg KH
2022-10-14 7:18 ` Greg KH
2022-10-14 8:20 ` Gupta, Nipun
2022-10-14 8:20 ` Gupta, Nipun
2022-10-14 4:40 ` [RFC PATCH v4 3/8] iommu/arm-smmu-v3: support ops registration for CDX bus Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 4:51 ` Gupta, Nipun
2022-10-14 4:51 ` Gupta, Nipun
2022-10-14 4:40 ` [RFC PATCH v4 4/8] bux/cdx: support dma configuration for CDX devices Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 4:40 ` [RFC PATCH v4 5/8] bus/cdx: add bus and device attributes Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 4:40 ` [RFC PATCH v4 6/8] irq/msi: use implicit msi domain for alloc and free Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 4:40 ` [RFC PATCH v4 7/8] bus/cdx: add cdx-MSI domain with gic-its domain as parent Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-17 13:08 ` kernel test robot
2022-11-17 19:10 ` Thomas Gleixner
2022-11-17 19:10 ` Thomas Gleixner
2022-10-14 4:40 ` [RFC PATCH v4 8/8] bus/cdx: add cdx controller Nipun Gupta
2022-10-14 4:40 ` Nipun Gupta
2022-10-14 14:10 ` [RFC PATCH v4 0/8] add support for CDX bus Rob Herring
2022-10-14 14:10 ` Rob Herring
2022-10-17 10:08 ` Gupta, Nipun
2022-10-17 10:08 ` Gupta, Nipun
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