linux-kernel - Re: [PATCH RFC PREVIEW 1/6] iommu/vt-d: Separate page request queue from SVM

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Message-ID: <c94d1463-4710-41fa-9936-fca1a0c2a275@linux.intel.com>
Date: Wed, 4 Sep 2024 19:07:20 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Joel Granados <j.granados@...sung.com>
Cc: baolu.lu@...ux.intel.com, Klaus Jensen <its@...elevant.dk>,
 David Woodhouse <dwmw2@...radead.org>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Jason Gunthorpe <jgg@...pe.ca>, Kevin Tian <kevin.tian@...el.com>,
 Minwoo Im <minwoo.im@...sung.com>, linux-kernel@...r.kernel.org,
 iommu@...ts.linux.dev, Klaus Jensen <k.jensen@...sung.com>
Subject: Re: [PATCH RFC PREVIEW 1/6] iommu/vt-d: Separate page request queue
 from SVM

On 2024/9/4 17:12, Joel Granados wrote:
> On Mon, Aug 26, 2024 at 09:09:14PM +0800, Baolu Lu wrote:
>> On 2024/8/26 19:40, Klaus Jensen wrote:
>>> From: Joel Granados<j.granados@...sung.com>
>>>
>>> IO page faults are no longer dependent on CONFIG_INTEL_IOMMU_SVM. Move
>>> all Page Request Queue (PRQ) functions that handle prq events to a new
>>> file in drivers/iommu/intel/prq.c. The page_req_des struct is made
>>> available in drivers/iommu/intel/iommu.h.
>>>
>>> No functional changes are intended. This is a preparation patch to
>>> enable the use of IO page faults outside the SVM and nested use cases.
>>>
>>> Signed-off-by: Joel Granados<j.granados@...sung.com>
>>> ---
>>>    drivers/iommu/intel/Makefile |   2 +-
>>>    drivers/iommu/intel/iommu.c  |  18 +--
>>>    drivers/iommu/intel/iommu.h  |  40 +++++-
>>>    drivers/iommu/intel/prq.c    | 290 ++++++++++++++++++++++++++++++++++++++++
>>>    drivers/iommu/intel/svm.c    | 308 -------------------------------------------
>>>    5 files changed, 331 insertions(+), 327 deletions(-)
>>>
>>> diff --git a/drivers/iommu/intel/Makefile b/drivers/iommu/intel/Makefile
>>> index c8beb0281559..d3bb0798092d 100644
>>> --- a/drivers/iommu/intel/Makefile
>>> +++ b/drivers/iommu/intel/Makefile
>>> @@ -1,6 +1,6 @@
>>>    # SPDX-License-Identifier: GPL-2.0
>>>    obj-$(CONFIG_DMAR_TABLE) += dmar.o
>>> -obj-$(CONFIG_INTEL_IOMMU) += iommu.o pasid.o nested.o cache.o
>>> +obj-$(CONFIG_INTEL_IOMMU) += iommu.o pasid.o nested.o cache.o prq.o
>>>    obj-$(CONFIG_DMAR_TABLE) += trace.o cap_audit.o
>>>    obj-$(CONFIG_DMAR_PERF) += perf.o
>>>    obj-$(CONFIG_INTEL_IOMMU_DEBUGFS) += debugfs.o
>> Thanks for the patch! Now that IOPF is separate from SVA, the Kconfig
>> needs to be updated accordingly.
>>
>> diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig
>> index f52fb39c968e..2888671c9278 100644
>> --- a/drivers/iommu/intel/Kconfig
>> +++ b/drivers/iommu/intel/Kconfig
>> @@ -15,6 +15,7 @@ config INTEL_IOMMU
>>           select DMA_OPS
>>           select IOMMU_API
>>           select IOMMU_IOVA
>> +       select IOMMU_IOPF
> This will force IOMMU_IOPF when INTEL_IOMMU is selected. You do this in
> order to use IOPF if available, but it wont conflict with Intel IOMMU's
> that do not support IOPF. right?

Intel VT-d includes a bit in the capability registers that indicates
whether PRI is supported by the hardware. Therefore, there should be no
conflict.

Thanks,
baolu