[dpdk-dev] [PATCH v4 1/5] mem: add function for checking memsegs IOVAs addresses

[Alejandro Lucero]

A device can suffer addressing limitations. This functions checks
memsegs have iovas within the supported range based on dma mask.

PMD should use this during initialization if supported devices
suffer addressing limitations, returning an error if this function
returns memsegs out of range.

Another potential usage is for emulated IOMMU hardware with addressing
limitations.

Applicable to v17.11.3 only.

Signed-off-by: Alejandro Lucero <alejandro.lucero at netronome.com>
Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
 lib/librte_eal/common/eal_common_memory.c  | 48 ++++++++++++++++++++++++++++++
 lib/librte_eal/common/include/rte_memory.h |  3 ++
 lib/librte_eal/rte_eal_version.map         |  1 +
 3 files changed, 52 insertions(+)

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index fc6c44d..00ab393 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -109,6 +109,54 @@
 	}
 }
 
+#if defined(RTE_ARCH_X86)
+#define X86_VA_WIDTH 47 /* From Documentation/x86/x86_64/mm.txt */
+#define MAX_DMA_MASK_BITS X86_VA_WIDTH
+#else
+/* 63 bits is good enough for a sanity check */
+#define MAX_DMA_MASK_BITS 63
+#endif
+
+/* check memseg iovas are within the required range based on dma mask */
+int
+rte_eal_check_dma_mask(uint8_t maskbits)
+{
+
+	const struct rte_mem_config *mcfg;
+	uint64_t mask;
+	int i;
+
+	/* sanity check */
+	if (maskbits > MAX_DMA_MASK_BITS) {
+		RTE_LOG(INFO, EAL, "wrong dma mask size %u (Max: %u)\n",
+				   maskbits, MAX_DMA_MASK_BITS);
+		return -1;
+	}
+
+	/* create dma mask */
+	mask = ~((1ULL << maskbits) - 1);
+
+	/* get pointer to global configuration */
+	mcfg = rte_eal_get_configuration()->mem_config;
+
+	for (i = 0; i < RTE_MAX_MEMSEG; i++) {
+		if (mcfg->memseg[i].addr == NULL)
+			break;
+
+		if (mcfg->memseg[i].iova & mask) {
+			RTE_LOG(INFO, EAL,
+				"memseg[%d] iova %"PRIx64" out of range:\n",
+				i, mcfg->memseg[i].iova);
+
+			RTE_LOG(INFO, EAL, "\tusing dma mask %"PRIx64"\n",
+				mask);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 /* return the number of memory channels */
 unsigned rte_memory_get_nchannel(void)
 {
diff --git a/lib/librte_eal/common/include/rte_memory.h b/lib/librte_eal/common/include/rte_memory.h
index 80a8fc0..b2a0168 100644
--- a/lib/librte_eal/common/include/rte_memory.h
+++ b/lib/librte_eal/common/include/rte_memory.h
@@ -209,6 +209,9 @@ struct rte_memseg {
  */
 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/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index f4f46c1..aa6cf87 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -184,6 +184,7 @@ DPDK_17.11 {
 
 	rte_eal_create_uio_dev;
 	rte_bus_get_iommu_class;
+	rte_eal_check_dma_mask;
 	rte_eal_has_pci;
 	rte_eal_iova_mode;
 	rte_eal_mbuf_default_mempool_ops;
-- 
1.9.1