[dpdk-dev] [PATCH v3 05/11] bus: get iommu class

[santosh]

On Friday 14 July 2017 01:37 PM, Hemant Agrawal wrote:

> On 7/11/2017 11:46 AM, Santosh Shukla wrote:
>> API(rte_bus_get_iommu_class) helps to automatically detect and select
>> appropriate iova mapping scheme for iommu capable device on that bus.
>>
>> Algorithm for iova scheme selection for bus:
>> 0. Iterate through bus_list.
>> 1. Collect each bus iova mode value and update into 'mode' var.
>> 2. Here value '1' is _pa and value '2' is _va mode.
>> So mode selection scheme is like:
>> if mode == 2 then iova mode is _va.
>> if mode == 1 then iova mode is _pa
>> if mode  == 3 then iova mode ia _pa.
>>
>> So mode !=2  will be default iova mode.
>>
>> Signed-off-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
>> Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
>> ---
>>  lib/librte_eal/bsdapp/eal/rte_eal_version.map   |  1 +
>>  lib/librte_eal/common/eal_common_bus.c          | 23 +++++++++++++++++++++++
>>  lib/librte_eal/common/eal_common_pci.c          |  1 +
>>  lib/librte_eal/common/include/rte_bus.h         | 22 ++++++++++++++++++++++
>>  lib/librte_eal/linuxapp/eal/rte_eal_version.map |  1 +
>>  5 files changed, 48 insertions(+)
>>
>> diff --git a/lib/librte_eal/bsdapp/eal/rte_eal_version.map b/lib/librte_eal/bsdapp/eal/rte_eal_version.map
>> index 33c2c32c0..a2dd65a33 100644
>> --- a/lib/librte_eal/bsdapp/eal/rte_eal_version.map
>> +++ b/lib/librte_eal/bsdapp/eal/rte_eal_version.map
>> @@ -202,6 +202,7 @@ DPDK_17.08 {
>>      rte_bus_find_by_name;
>>      rte_pci_match;
>>      rte_pci_get_iommu_class;
>> +    rte_bus_get_iommu_class;
>>
>>  } DPDK_17.05;
>>
>> diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
>> index 08bec2d93..5d5753ac9 100644
>> --- a/lib/librte_eal/common/eal_common_bus.c
>> +++ b/lib/librte_eal/common/eal_common_bus.c
>> @@ -222,3 +222,26 @@ rte_bus_find_by_device_name(const char *str)
>>          c[0] = '\0';
>>      return rte_bus_find(NULL, bus_can_parse, name);
>>  }
>> +
>> +
>> +/*
>> + * Get iommu class of devices on the bus.
>> + */
>> +enum rte_iova_mode
>> +rte_bus_get_iommu_class(void)
>> +{
>> +    int mode = 0;
>> +    struct rte_bus *bus;
>> +
>> +    TAILQ_FOREACH(bus, &rte_bus_list, next) {
>> +
>> +        if (bus->get_iommu_class)
>> +            mode |= bus->get_iommu_class();
>> +    }
>> +
>
> If you change the default return as '0' for buses. This code will work.
> e.g. PCI will return '0' - when no device is probed. FSL MC will return VA. the default mode will be 'VA'
>
I'm confused why it won't work for fslmc case?

Let me walk through the code:

If no-pci device Or (future) no-platform device probed then bus opt 
to use default mapping scheme .. which is iova_pa(default scheme).

Lets take PCI_bus example:
bus->get_iommu_class()
	---> bus->_pci_get_iommu_class()
		* Now consider that no interface bound to any of PCI device, then
		  it will return RTE_IOVA_PA mode to rte_bus layer (aka bus->get_iommu_class).
		  So the iova mapping result from iommu_class scan is RTE_IOVA_PA (default).
		  It works for PCI_bus case, tested for both iova_va and iova_pa case, no-pci device case.

Now in fslmc bus case:
bus->get_iommu_class()
	---> bus->_fslmc_get_iommu_class()
		
		* IIUC your comment - You want fslmc bus to return RTE_IOVA_VA if no device
		  detected, Right?
		  if so then your fslmc bus handle should do something like below
			-- If no device on fslmc bus : return RTE_IOVA_VA.
			-- If device detected on fslmc bus and bound to iommu driver : return RTE_IOVA_VA
			-- If device detected fslmc but not bound to iommu drv : return RTE_IOVA_PA..

make sense? If not then can you describe fslmc mapping scheme? 

> if fslmc is not present. The default mode will be PA.
>
>> +    if (mode != RTE_IOVA_VA) {
>> +        /* Use default IOVA mode */
>> +        mode = RTE_IOVA_PA;
>> +    }
>> +    return mode;
>> +}
>> diff --git a/lib/librte_eal/common/eal_common_pci.c b/lib/librte_eal/common/eal_common_pci.c
>> index 8b6ecebd6..bdf2e7c3a 100644
>> --- a/lib/librte_eal/common/eal_common_pci.c
>> +++ b/lib/librte_eal/common/eal_common_pci.c
>> @@ -552,6 +552,7 @@ struct rte_pci_bus rte_pci_bus = {
>>          .plug = pci_plug,
>>          .unplug = pci_unplug,
>>          .parse = pci_parse,
>> +        .get_iommu_class = rte_pci_get_iommu_class,
>>      },
>>      .device_list = TAILQ_HEAD_INITIALIZER(rte_pci_bus.device_list),
>>      .driver_list = TAILQ_HEAD_INITIALIZER(rte_pci_bus.driver_list),
>> diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
>> index 7a0cfb165..8b2805b7f 100644
>> --- a/lib/librte_eal/common/include/rte_bus.h
>> +++ b/lib/librte_eal/common/include/rte_bus.h
>> @@ -181,6 +181,17 @@ struct rte_bus_conf {
>>      enum rte_bus_scan_mode scan_mode; /**< Scan policy. */
>>  };
>>
>> +
>> +/**
>> + * Get iommu class of devices on the bus.
>> + * Check that those devices are attached to iommu driver.
>> + *
>> + * @return
>> + *      enum rte_iova_mode value.
>> + */
>> +typedef enum rte_iova_mode (*rte_bus_get_iommu_class_t)(void);
>> +
>> +
>>  /**
>>   * A structure describing a generic bus.
>>   */
>> @@ -194,6 +205,7 @@ struct rte_bus {
>>      rte_bus_unplug_t unplug;     /**< Remove single device from driver */
>>      rte_bus_parse_t parse;       /**< Parse a device name */
>>      struct rte_bus_conf conf;    /**< Bus configuration */
>> +    rte_bus_get_iommu_class_t get_iommu_class; /**< Get iommu class */
>>  };
>>
>>  /**
>> @@ -293,6 +305,16 @@ struct rte_bus *rte_bus_find_by_device(const struct rte_device *dev);
>>   */
>>  struct rte_bus *rte_bus_find_by_name(const char *busname);
>>
>> +
>> +/**
>> + * Get iommu class of devices on the bus.
>> + * Check that those devices are attached to iommu driver.
>> + *
>> + * @return
>> + *     enum rte_iova_mode value.
>> + */
>> +enum rte_iova_mode rte_bus_get_iommu_class(void);
>> +
>>  /**
>>   * Helper for Bus registration.
>>   * The constructor has higher priority than PMD constructors.
>> diff --git a/lib/librte_eal/linuxapp/eal/rte_eal_version.map b/lib/librte_eal/linuxapp/eal/rte_eal_version.map
>> index 044f89c7c..186c7b0fd 100644
>> --- a/lib/librte_eal/linuxapp/eal/rte_eal_version.map
>> +++ b/lib/librte_eal/linuxapp/eal/rte_eal_version.map
>> @@ -207,6 +207,7 @@ DPDK_17.08 {
>>      rte_bus_find_by_name;
>>      rte_pci_match;
>>      rte_pci_get_iommu_class;
>> +    rte_bus_get_iommu_class;
>>
>>  } DPDK_17.05;
>>
>>
>
>