From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Feng Kan <fkan@apm.com>
Cc: "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
Hanjun Guo <hanjun.guo@linaro.org>, Jon Masters <jcm@redhat.com>,
Robert Moore <robert.moore@intel.com>,
Robin Murphy <robin.murphy@arm.com>,
Zhang Rui <rui.zhang@intel.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Nate Watterson <nwatters@codeaurora.org>
Subject: Re: [PATCH v3 0/5] ACPI: DMA ranges management
Date: Fri, 1 Dec 2017 10:39:43 +0000 [thread overview]
Message-ID: <20171201103943.GA25066@red-moon> (raw)
In-Reply-To: <CAL85gmDkrwuYPTyUn_cw1bQL2y9D65z2zJe3e79qjifN5Q_7-g@mail.gmail.com>
On Thu, Nov 30, 2017 at 04:43:00PM -0800, Feng Kan wrote:
> On Wed, Nov 29, 2017 at 11:28 PM, Feng Kan <fkan@apm.com> wrote:
> > On Thu, Aug 3, 2017 at 5:32 AM, Lorenzo Pieralisi
> > <lorenzo.pieralisi@arm.com> wrote:
> >> This patch series is v3 of a previous posting:
> >>
> >> v2->v3:
> >> - Fixed DMA masks computation
> >> - Fixed size computation overflow in acpi_dma_get_range()
> >>
> >> v1->v2:
> >> - Reworked acpi_dma_get_range() flow and logs
> >> - Added IORT named component address limits
> >> - Renamed acpi_dev_get_resources() helper function
> >> - Rebased against v4.13-rc3
> >>
> >> v2: http://lkml.kernel.org/r/20170731152323.32488-1-lorenzo.pieralisi@arm.com
> >> v1: http://lkml.kernel.org/r/20170720144517.32529-1-lorenzo.pieralisi@arm.com
> >>
> >> -- Original cover letter --
> >>
> >> As reported in:
> >>
> >> http://lkml.kernel.org/r/CAL85gmA_SSCwM80TKdkZqEe+S1beWzDEvdki1kpkmUTDRmSP7g@mail.gmail.com
> >>
> >> the bus connecting devices to an IOMMU bus can be smaller in size than
> >> the IOMMU input address bits which results in devices DMA HW bugs in
> >> particular related to IOVA allocation (ie chopping of higher address
> >> bits owing to system bus HW capabilities mismatch with the IOMMU).
> >>
> >> Fortunately this problem can be solved through an already present but never
> >> used ACPI 6.2 firmware bindings (ie _DMA object) allowing to define the DMA
> >> window for a specific bus in ACPI and therefore all upstream devices
> >> connected to it.
> >>
> >> This small patch series enables _DMA parsing in ACPI core code and
> >> use it in ACPI IORT code in order to detect DMA ranges for devices and
> >> update their data structures to make them work with their related DMA
> >> addressing restrictions.
> >>
> >> Cc: Will Deacon <will.deacon@arm.com>
> >> Cc: Hanjun Guo <hanjun.guo@linaro.org>
> >> Cc: Feng Kan <fkan@apm.com>
> >> Cc: Jon Masters <jcm@redhat.com>
> >> Cc: Robert Moore <robert.moore@intel.com>
> >> Cc: Robin Murphy <robin.murphy@arm.com>
> >> Cc: Zhang Rui <rui.zhang@intel.com>
> >> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> >>
> >> Lorenzo Pieralisi (5):
> >> ACPICA: resource_mgr: Allow _DMA method in walk resources
> >> ACPI: Make acpi_dev_get_resources() method agnostic
> >> ACPI: Introduce DMA ranges parsing
> >> ACPI: Make acpi_dma_configure() DMA regions aware
> >> ACPI/IORT: Add IORT named component memory address limits
> >>
> >> drivers/acpi/acpica/rsxface.c | 7 ++--
> >> drivers/acpi/arm64/iort.c | 57 ++++++++++++++++++++++++++-
> >> drivers/acpi/resource.c | 82 +++++++++++++++++++++++++++++---------
> >> drivers/acpi/scan.c | 91 +++++++++++++++++++++++++++++++++++++++----
> >> include/acpi/acnames.h | 1 +
> >> include/acpi/acpi_bus.h | 2 +
> >> include/linux/acpi.h | 8 ++++
> >> include/linux/acpi_iort.h | 5 ++-
> >> 8 files changed, 219 insertions(+), 34 deletions(-)
> >>
> >> --
> >> 2.10.0
> >>
> > Lorenzo:
> >
> > A network driver can use pci_set_dma_mask or its like to override what
> > is done with this patch here.
> > Which would result in iova allocation greater than the original _DMA
> > aperture. Should we force
> > the dma_set_mask to not change if an existing mask is already set?
>
> Let me clarify the question some more, in our system the IOMMU supports only
> 42 bits of address. With your _DMA aperture patch, the initial dma_mask and
> coherent_mask are correctly set by the code. However, the device driver can
> set the dma_mask and coherent mask at a later point which over writes the
> initial setting by your code. In which case, once the iova is exhausted with the
> 32 bit address, it will start seeking more iova address via the
> dma_limit. In this
> case it would fail my system since the iommu.aperture_end is that of 48 bits
> as derived from ias field in the SMMU.
>
> Should the dma_limit be the smallest of driver->dma_mask, iommu.aperture_end and
> your _DMA aperture size via ACPI table? Rather than just the
> driver->dma_mask and
> iommu.aperture_end. This will ensure the smallest/correct aperture is used.
IIUC Nate already reported this issue - I will sync with Robin to
check the status of this thread:
https://marc.info/?l=linux-acpi&m=150108156230455&w=2
Thanks,
Lorenzo
prev parent reply other threads:[~2017-12-01 10:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-03 12:32 [PATCH v3 0/5] ACPI: DMA ranges management Lorenzo Pieralisi
2017-08-03 12:32 ` [PATCH v3 1/5] ACPICA: resource_mgr: Allow _DMA method in walk resources Lorenzo Pieralisi
2017-08-03 12:32 ` [PATCH v3 2/5] ACPI: Make acpi_dev_get_resources() method agnostic Lorenzo Pieralisi
2017-08-03 12:32 ` [PATCH v3 3/5] ACPI: Introduce DMA ranges parsing Lorenzo Pieralisi
2017-08-06 5:12 ` kbuild test robot
2017-08-06 9:42 ` Lorenzo Pieralisi
2017-08-06 11:21 ` Rafael J. Wysocki
2017-08-03 12:32 ` [PATCH v3 4/5] ACPI: Make acpi_dma_configure() DMA regions aware Lorenzo Pieralisi
2017-08-03 12:32 ` [PATCH v3 5/5] ACPI/IORT: Add IORT named component memory address limits Lorenzo Pieralisi
2017-08-03 13:25 ` [PATCH v3 0/5] ACPI: DMA ranges management Hanjun Guo
2017-08-03 15:16 ` Will Deacon
2017-08-03 15:45 ` Nate Watterson
2017-08-03 17:21 ` Robin Murphy
2017-08-09 21:14 ` Jeremy Linton
2017-08-11 8:52 ` Lorenzo Pieralisi
2017-08-14 18:41 ` Feng Kan
2017-11-30 7:28 ` Feng Kan
2017-12-01 0:43 ` Feng Kan
2017-12-01 10:39 ` Lorenzo Pieralisi [this message]
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