Re: [dpdk-dev] [PATCH v3 1/6] mem: add function for checking memsegs IOVAs addresses

["Tu, Lijuan" <lijuan.tu@intel.com>]

Hi 

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Alejandro Lucero
> Sent: Friday, October 5, 2018 8:45 PM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH v3 1/6] mem: add function for checking
> memsegs IOVAs addresses
> 
> A device can suffer addressing limitations. This function checks memsegs
> have iovas within the supported range based on dma mask.
> 
> PMDs should use this function during initialization if device suffers
> addressing limitations, returning an error if this function returns memsegs
> out of range.
> 
> Another usage is for emulated IOMMU hardware with addressing limitations.
> 
> It is necessary to save the most restricted dma mask for checking out
> memory allocated dynamically after initialization.
> 
> Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
> Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
>  doc/guides/rel_notes/release_18_11.rst            | 10 ++++
>  lib/librte_eal/common/eal_common_memory.c         | 60
> +++++++++++++++++++++++
>  lib/librte_eal/common/include/rte_eal_memconfig.h |  3 ++
>  lib/librte_eal/common/include/rte_memory.h        |  3 ++
>  lib/librte_eal/common/malloc_heap.c               | 12 +++++
>  lib/librte_eal/linuxapp/eal/eal.c                 |  2 +
>  lib/librte_eal/rte_eal_version.map                |  1 +
>  7 files changed, 91 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/release_18_11.rst
> b/doc/guides/rel_notes/release_18_11.rst
> index 2133a5b..c806dc6 100644
> --- a/doc/guides/rel_notes/release_18_11.rst
> +++ b/doc/guides/rel_notes/release_18_11.rst
> @@ -104,6 +104,14 @@ New Features
>    the specified port. The port must be stopped before the command call in
> order
>    to reconfigure queues.
> 
> +* **Added check for ensuring allocated memory addressable by devices.**
> +
> +  Some devices can have addressing limitations so a new function,
> + ``rte_eal_check_dma_mask``, has been added for checking allocated
> + memory is  not out of the device range. Because now memory can be
> + dynamically allocated  after initialization, a dma mask is kept and
> + any new allocated memory will be  checked out against that dma mask
> + and rejected if out of range. If more than  one device has addressing
> limitations, the dma mask is the more restricted one.
> 
>  API Changes
>  -----------
> @@ -156,6 +164,8 @@ ABI Changes
>         ``rte_config`` structure on account of improving DPDK usability
> when
>         using either ``--legacy-mem`` or ``--single-file-segments`` flags.
> 
> +* eal: added ``dma_maskbits`` to ``rte_mem_config`` for keeping more
> restricted
> +       dma mask based on devices addressing limitations.
> 
>  Removed Items
>  -------------
> diff --git a/lib/librte_eal/common/eal_common_memory.c
> b/lib/librte_eal/common/eal_common_memory.c
> index 0b69804..c482f0d 100644
> --- a/lib/librte_eal/common/eal_common_memory.c
> +++ b/lib/librte_eal/common/eal_common_memory.c
> @@ -385,6 +385,66 @@ struct virtiova {
>  	rte_memseg_walk(dump_memseg, f);
>  }
> 
> +static int
> +check_iova(const struct rte_memseg_list *msl __rte_unused,
> +		const struct rte_memseg *ms, void *arg) {
> +	uint64_t *mask = arg;
> +	rte_iova_t iova;
> +
> +	/* higher address within segment */
> +	iova = (ms->iova + ms->len) - 1;
> +	if (!(iova & *mask))
> +		return 0;
> +
> +	RTE_LOG(DEBUG, EAL, "memseg iova %"PRIx64", len %zx, out of
> range\n",
> +			    ms->iova, ms->len);
> +
> +	RTE_LOG(DEBUG, EAL, "\tusing dma mask %"PRIx64"\n", *mask);
> +	return 1;
> +}
> +
> +#if defined(RTE_ARCH_64)
> +#define MAX_DMA_MASK_BITS 63
> +#else
> +#define MAX_DMA_MASK_BITS 31
> +#endif
> +
> +/* check memseg iovas are within the required range based on dma mask
> +*/ int __rte_experimental rte_eal_check_dma_mask(uint8_t maskbits) {
> +	struct rte_mem_config *mcfg =
> rte_eal_get_configuration()->mem_config;
> +	uint64_t mask;
> +
> +	/* sanity check */
> +	if (maskbits > MAX_DMA_MASK_BITS) {
> +		RTE_LOG(ERR, EAL, "wrong dma mask size %u (Max: %u)\n",
> +				   maskbits, MAX_DMA_MASK_BITS);
> +		return -1;
> +	}
> +
> +	/* create dma mask */
> +	mask = ~((1ULL << maskbits) - 1);
> +
> +	if (rte_memseg_walk(check_iova, &mask))

[Lijuan]In my environment, testpmd halts at rte_memseg_walk() when maskbits is 0.

> +		/*
> +		 * Dma mask precludes hugepage usage.
> +		 * This device can not be used and we do not need to keep
> +		 * the dma mask.
> +		 */
> +		return 1;
> +
> +	/*
> +	 * we need to keep the more restricted maskbit for checking
> +	 * potential dynamic memory allocation in the future.
> +	 */
> +	mcfg->dma_maskbits = mcfg->dma_maskbits == 0 ? maskbits :
> +			     RTE_MIN(mcfg->dma_maskbits, maskbits);
> +
> +	return 0;
> +}
> +
>  /* return the number of memory channels */  unsigned
> rte_memory_get_nchannel(void)  { diff --git
> a/lib/librte_eal/common/include/rte_eal_memconfig.h
> b/lib/librte_eal/common/include/rte_eal_memconfig.h
> index 62a21c2..b5dff70 100644
> --- a/lib/librte_eal/common/include/rte_eal_memconfig.h
> +++ b/lib/librte_eal/common/include/rte_eal_memconfig.h
> @@ -81,6 +81,9 @@ struct rte_mem_config {
>  	/* legacy mem and single file segments options are shared */
>  	uint32_t legacy_mem;
>  	uint32_t single_file_segments;
> +
> +	/* keeps the more restricted dma mask */
> +	uint8_t dma_maskbits;
>  } __attribute__((__packed__));
> 
> 
> diff --git a/lib/librte_eal/common/include/rte_memory.h
> b/lib/librte_eal/common/include/rte_memory.h
> index 14bd277..c349d6c 100644
> --- a/lib/librte_eal/common/include/rte_memory.h
> +++ b/lib/librte_eal/common/include/rte_memory.h
> @@ -454,6 +454,9 @@ typedef int (*rte_memseg_list_walk_t)(const struct
> rte_memseg_list *msl,
>   */
>  unsigned rte_memory_get_nrank(void);
> 
> +/* check memsegs iovas are within a range based on dma mask */ int
> +rte_eal_check_dma_mask(uint8_t maskbits);
> +
>  /**
>   * Drivers based on uio will not load unless physical
>   * addresses are obtainable. It is only possible to get diff --git
> a/lib/librte_eal/common/malloc_heap.c
> b/lib/librte_eal/common/malloc_heap.c
> index ac7bbb3..3b5b2b6 100644
> --- a/lib/librte_eal/common/malloc_heap.c
> +++ b/lib/librte_eal/common/malloc_heap.c
> @@ -259,11 +259,13 @@ struct malloc_elem *
>  		int socket, unsigned int flags, size_t align, size_t bound,
>  		bool contig, struct rte_memseg **ms, int n_segs)  {
> +	struct rte_mem_config *mcfg =
> rte_eal_get_configuration()->mem_config;
>  	struct rte_memseg_list *msl;
>  	struct malloc_elem *elem = NULL;
>  	size_t alloc_sz;
>  	int allocd_pages;
>  	void *ret, *map_addr;
> +	uint64_t mask;
> 
>  	alloc_sz = (size_t)pg_sz * n_segs;
> 
> @@ -291,6 +293,16 @@ struct malloc_elem *
>  		goto fail;
>  	}
> 
> +	if (mcfg->dma_maskbits) {
> +		mask = ~((1ULL << mcfg->dma_maskbits) - 1);
> +		if (rte_eal_check_dma_mask(mask)) {
> +			RTE_LOG(ERR, EAL,
> +				"%s(): couldn't allocate memory due to DMA mask\n",
> +				__func__);
> +			goto fail;
> +		}
> +	}
> +
>  	/* add newly minted memsegs to malloc heap */
>  	elem = malloc_heap_add_memory(heap, msl, map_addr, alloc_sz);
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal.c
> b/lib/librte_eal/linuxapp/eal/eal.c
> index 4a55d3b..dfe1b8c 100644
> --- a/lib/librte_eal/linuxapp/eal/eal.c
> +++ b/lib/librte_eal/linuxapp/eal/eal.c
> @@ -263,6 +263,8 @@ enum rte_iova_mode
>  	 * processes could later map the config into this exact location */
>  	rte_config.mem_config->mem_cfg_addr = (uintptr_t)
> rte_mem_cfg_addr;
> 
> +	rte_config.mem_config->dma_maskbits = 0;
> +
>  }
> 
>  /* attach to an existing shared memory config */ diff --git
> a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
> index 73282bb..2baefce 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -291,6 +291,7 @@ EXPERIMENTAL {
>  	rte_devargs_parsef;
>  	rte_devargs_remove;
>  	rte_devargs_type_count;
> +	rte_eal_check_dma_mask;
>  	rte_eal_cleanup;
>  	rte_eal_hotplug_add;
>  	rte_eal_hotplug_remove;
> --
> 1.9.1