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From: Alex Williamson <alex.williamson@redhat.com>
To: Eric Auger <eric.auger@redhat.com>
Cc: kevin.tian@intel.com, jacob.jun.pan@linux.intel.com,
	ashok.raj@intel.com, kvm@vger.kernel.org, joro@8bytes.org,
	will.deacon@arm.com, linux-kernel@vger.kernel.org,
	marc.zyngier@arm.com, iommu@lists.linux-foundation.org,
	yi.l.liu@intel.com, vincent.stehle@arm.com, robin.murphy@arm.com,
	kvmarm@lists.cs.columbia.edu, eric.auger.pro@gmail.com
Subject: Re: [PATCH v8 05/29] iommu: Add a timeout parameter for PRQ response
Date: Mon, 3 Jun 2019 16:32:14 -0600
Message-ID: <20190603163214.483884a7@x1.home> (raw)
In-Reply-To: <20190526161004.25232-6-eric.auger@redhat.com>

On Sun, 26 May 2019 18:09:40 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> 
> When an IO page request is processed outside IOMMU subsystem, response
> can be delayed or lost. Add a tunable setup parameter such that user can
> choose the timeout for IOMMU to track pending page requests.
> 
> This timeout mechanism is a basic safety net which can be implemented in
> conjunction with credit based or device level page response exception
> handling.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>  .../admin-guide/kernel-parameters.txt         |  8 +++++
>  drivers/iommu/iommu.c                         | 29 +++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 138f6664b2e2..b43f0893d252 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1813,6 +1813,14 @@
>  			1 - Bypass the IOMMU for DMA.
>  			unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
>  
> +	iommu.prq_timeout=
> +			Timeout in seconds to wait for page response
> +			of a pending page request.
> +			Format: <integer>
> +			Default: 10
> +			0 - no timeout tracking
> +			1 to 100 - allowed range
> +
>  	io7=		[HW] IO7 for Marvel based alpha systems
>  			See comment before marvel_specify_io7 in
>  			arch/alpha/kernel/core_marvel.c.
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 13b301cfb10f..64e87d56f471 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -45,6 +45,19 @@ static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA;
>  #endif
>  static bool iommu_dma_strict __read_mostly = true;
>  
> +/*
> + * Timeout to wait for page response of a pending page request. This is
> + * intended as a basic safty net in case a pending page request is not
> + * responded for an exceptionally long time. Device may also implement
> + * its own protection mechanism against this exception.
> + * Units are in jiffies with a range between 1 - 100 seconds equivalent.
> + * Default to 10 seconds.
> + * Setting 0 means no timeout tracking.
> + */
> +#define IOMMU_PAGE_RESPONSE_MAX_TIMEOUT (HZ * 100)
> +#define IOMMU_PAGE_RESPONSE_DEF_TIMEOUT (HZ * 10)
> +static unsigned long prq_timeout = IOMMU_PAGE_RESPONSE_DEF_TIMEOUT;
> +
>  struct iommu_group {
>  	struct kobject kobj;
>  	struct kobject *devices_kobj;
> @@ -157,6 +170,22 @@ static int __init iommu_dma_setup(char *str)
>  }
>  early_param("iommu.strict", iommu_dma_setup);
>  
> +static int __init iommu_set_prq_timeout(char *str)
> +{
> +	unsigned long timeout;
> +
> +	if (!str)
> +		return -EINVAL;
> +	timeout = simple_strtoul(str, NULL, 0);
> +	timeout = timeout * HZ;
> +	if (timeout > IOMMU_PAGE_RESPONSE_MAX_TIMEOUT)
> +		return -EINVAL;
> +	prq_timeout = timeout;
> +
> +	return 0;
> +}
> +early_param("iommu.prq_timeout", iommu_set_prq_timeout);
> +
>  static ssize_t iommu_group_attr_show(struct kobject *kobj,
>  				     struct attribute *__attr, char *buf)
>  {

It doesn't seem to make much sense to include this patch without also
including "iommu: handle page response timeout".  Was that one lost?
Dropped?  Lives elsewhere?  Thanks,

Alex
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  reply index

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-26 16:09 [PATCH v8 00/29] SMMUv3 Nested Stage Setup Eric Auger
2019-05-26 16:09 ` [PATCH v8 01/29] driver core: Add per device iommu param Eric Auger
2019-05-26 16:09 ` [PATCH v8 02/29] iommu: Introduce device fault data Eric Auger
2019-05-26 16:09 ` [PATCH v8 03/29] iommu: Introduce device fault report API Eric Auger
2019-05-26 16:09 ` [PATCH v8 04/29] iommu: Add recoverable fault reporting Eric Auger
2019-06-03 22:31   ` Alex Williamson
2019-06-04 15:48     ` Jacob Pan
2019-05-26 16:09 ` [PATCH v8 05/29] iommu: Add a timeout parameter for PRQ response Eric Auger
2019-06-03 22:32   ` Alex Williamson [this message]
2019-06-04 10:52     ` Jean-Philippe Brucker
2019-06-04 15:50       ` Jacob Pan
2019-05-26 16:09 ` [PATCH v8 06/29] trace/iommu: Add sva trace events Eric Auger
2019-05-26 16:09 ` [PATCH v8 07/29] iommu: Use device fault trace event Eric Auger
2019-05-26 16:09 ` [PATCH v8 08/29] iommu: Introduce attach/detach_pasid_table API Eric Auger
2019-05-26 16:09 ` [PATCH v8 09/29] iommu: Introduce cache_invalidate API Eric Auger
2019-05-26 16:09 ` [PATCH v8 10/29] iommu: Introduce bind/unbind_guest_msi Eric Auger
2019-05-26 16:09 ` [PATCH v8 11/29] iommu/arm-smmu-v3: Maintain a SID->device structure Eric Auger
2019-05-26 16:09 ` [PATCH v8 12/29] iommu/smmuv3: Dynamically allocate s1_cfg and s2_cfg Eric Auger
2019-05-26 16:09 ` [PATCH v8 13/29] iommu/smmuv3: Get prepared for nested stage support Eric Auger
2019-05-26 16:09 ` [PATCH v8 14/29] iommu/smmuv3: Implement attach/detach_pasid_table Eric Auger
2019-05-26 16:09 ` [PATCH v8 15/29] iommu/smmuv3: Introduce __arm_smmu_tlb_inv_asid/s1_range_nosync Eric Auger
2019-05-26 16:09 ` [PATCH v8 16/29] iommu/smmuv3: Implement cache_invalidate Eric Auger
2019-05-26 16:09 ` [PATCH v8 17/29] dma-iommu: Implement NESTED_MSI cookie Eric Auger
2019-05-26 16:09 ` [PATCH v8 18/29] iommu/smmuv3: Nested mode single MSI doorbell per domain enforcement Eric Auger
2019-05-26 16:09 ` [PATCH v8 19/29] iommu/smmuv3: Enforce incompatibility between nested mode and HW MSI regions Eric Auger
2019-05-26 16:09 ` [PATCH v8 20/29] iommu/smmuv3: Implement bind/unbind_guest_msi Eric Auger
2019-05-26 16:09 ` [PATCH v8 21/29] iommu/smmuv3: Report non recoverable faults Eric Auger
2019-05-26 16:09 ` [PATCH v8 22/29] vfio: VFIO_IOMMU_ATTACH/DETACH_PASID_TABLE Eric Auger
2019-06-03 22:32   ` Alex Williamson
2019-05-26 16:09 ` [PATCH v8 23/29] vfio: VFIO_IOMMU_CACHE_INVALIDATE Eric Auger
2019-06-14 12:38   ` Liu, Yi L
2019-06-14 13:17     ` Auger Eric
2019-05-26 16:09 ` [PATCH v8 24/29] vfio: VFIO_IOMMU_BIND/UNBIND_MSI Eric Auger
2019-06-03 22:32   ` Alex Williamson
2019-06-07  8:30     ` Auger Eric
2019-05-26 16:10 ` [PATCH v8 25/29] vfio-pci: Add a new VFIO_REGION_TYPE_NESTED region type Eric Auger
2019-06-03 22:31   ` Alex Williamson
2019-06-07  8:28     ` Auger Eric
2019-06-07 12:47       ` Jean-Philippe Brucker
2019-06-07 16:29       ` Alex Williamson
2019-05-26 16:10 ` [PATCH v8 26/29] vfio-pci: Register an iommu fault handler Eric Auger
2019-06-03 22:31   ` Alex Williamson
2019-06-04 16:11     ` Auger Eric
2019-06-05 22:45       ` Jacob Pan
2019-06-06 18:54         ` Jean-Philippe Brucker
2019-06-06 20:29           ` Jacob Pan
2019-06-07  7:02             ` Auger Eric
2019-06-07 10:28             ` Jean-Philippe Brucker
2019-06-07 17:43               ` Jacob Pan
2019-06-10 12:45                 ` Jean-Philippe Brucker
2019-06-10 21:31                   ` Jacob Pan
2019-06-11 13:14                     ` Jean-Philippe Brucker
2019-06-12 18:53                       ` Jacob Pan
2019-06-18 14:04                         ` Jean-Philippe Brucker
2019-06-19  0:19                           ` Jacob Pan
2019-06-19 11:44                             ` Jean-Philippe Brucker
2019-07-11 13:07                           ` Auger Eric
2019-06-07 12:48   ` Jean-Philippe Brucker
2019-06-07 14:18     ` Auger Eric
2019-05-26 16:10 ` [PATCH v8 27/29] vfio_pci: Allow to mmap the fault queue Eric Auger
2019-05-26 16:10 ` [PATCH v8 28/29] vfio-pci: Add VFIO_PCI_DMA_FAULT_IRQ_INDEX Eric Auger
2019-06-03 22:31   ` Alex Williamson
2019-06-04 16:11     ` Auger Eric
2019-05-26 16:10 ` [PATCH v8 29/29] vfio: Document nested stage control Eric Auger

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