[PATCH 1/4] bus/pci: Use force-noreplace flag when mapping PCI resources

[Jake Freeland]

When mapping PCI resources in secondary processes, use the
RTE_MAP_FORCE_ADDRESS_NOREPLACE flag to indicate that the
mapping must be made at the provided address.

Without this flag, the kernel might return a different address for
the mapping, even if the requested region was available.

Signed-off-by: Jake Freeland <jfree at FreeBSD.org>
---
 drivers/bus/pci/pci_common_uio.c | 4 +++-
 lib/eal/common/eal_private.h     | 7 ++++++-
 lib/eal/include/rte_eal_paging.h | 7 ++++++-
 lib/eal/unix/eal_unix_memory.c   | 8 +++++++-
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/pci/pci_common_uio.c b/drivers/bus/pci/pci_common_uio.c
index 30503bd23a..71974e9f56 100644
--- a/drivers/bus/pci/pci_common_uio.c
+++ b/drivers/bus/pci/pci_common_uio.c
@@ -10,6 +10,7 @@
 #include <sys/mman.h>
 
 #include <rte_eal.h>
+#include <rte_eal_paging.h>
 #include <rte_pci.h>
 #include <rte_bus_pci.h>
 #include <rte_tailq.h>
@@ -58,7 +59,8 @@ pci_uio_map_secondary(struct rte_pci_device *dev)
 
 			void *mapaddr = pci_map_resource(uio_res->maps[i].addr,
 					fd, (off_t)uio_res->maps[i].offset,
-					(size_t)uio_res->maps[i].size, 0);
+					(size_t)uio_res->maps[i].size,
+					RTE_MAP_FORCE_ADDRESS_NOREPLACE);
 
 			/* fd is not needed in secondary process, close it */
 			close(fd);
diff --git a/lib/eal/common/eal_private.h b/lib/eal/common/eal_private.h
index 04ba8ddb86..aaeb140eaf 100644
--- a/lib/eal/common/eal_private.h
+++ b/lib/eal/common/eal_private.h
@@ -211,7 +211,12 @@ enum eal_mem_reserve_flags {
 	 * @see RTE_MAP_FORCE_ADDRESS for description of possible consequences
 	 *      (although implementations are not required to use it).
 	 */
-	EAL_RESERVE_FORCE_ADDRESS = 1 << 1
+	EAL_RESERVE_FORCE_ADDRESS = 1 << 1,
+	/**
+	 * Force reserving memory at the requested address, but fail if a
+	 * preexisting mapping collides with the request.
+	 */
+	EAL_RESERVE_FORCE_ADDRESS_NOREPLACE = 1 << 2,
 };
 
 /**
diff --git a/lib/eal/include/rte_eal_paging.h b/lib/eal/include/rte_eal_paging.h
index c60317d0f5..7b1983b615 100644
--- a/lib/eal/include/rte_eal_paging.h
+++ b/lib/eal/include/rte_eal_paging.h
@@ -34,7 +34,12 @@ enum rte_map_flags {
 	 * may remove all other mappings in the requested region. However,
 	 * it is not required to do so, thus mapping with this flag may fail.
 	 */
-	RTE_MAP_FORCE_ADDRESS = 1 << 3
+	RTE_MAP_FORCE_ADDRESS = 1 << 3,
+	/**
+	 * Force mapping to the requested address, but fail if a preexisting
+	 * mapping collides with the request.
+	 */
+	RTE_MAP_FORCE_ADDRESS_NOREPLACE = 1 << 4,
 };
 
 /**
diff --git a/lib/eal/unix/eal_unix_memory.c b/lib/eal/unix/eal_unix_memory.c
index c540f1e838..61e914b8db 100644
--- a/lib/eal/unix/eal_unix_memory.c
+++ b/lib/eal/unix/eal_unix_memory.c
@@ -17,11 +17,13 @@
 #ifdef RTE_EXEC_ENV_LINUX
 #define EAL_DONTDUMP MADV_DONTDUMP
 #define EAL_DODUMP   MADV_DODUMP
+#define EAL_FIXED_NOREPLACE MAP_FIXED_NOREPLACE
 #elif defined RTE_EXEC_ENV_FREEBSD
 #define EAL_DONTDUMP MADV_NOCORE
 #define EAL_DODUMP   MADV_CORE
+#define EAL_FIXED_NOREPLACE (MAP_FIXED | MAP_EXCL)
 #else
-#error "madvise doesn't support this OS"
+#error "EAL doesn't support this OS"
 #endif
 
 static void *
@@ -68,6 +70,8 @@ eal_mem_reserve(void *requested_addr, size_t size, int flags)
 
 	if (flags & EAL_RESERVE_FORCE_ADDRESS)
 		sys_flags |= MAP_FIXED;
+	if (flags & EAL_RESERVE_FORCE_ADDRESS_NOREPLACE)
+		sys_flags |= EAL_FIXED_NOREPLACE;
 
 	return mem_map(requested_addr, size, PROT_NONE, sys_flags, -1, 0);
 }
@@ -124,6 +128,8 @@ rte_mem_map(void *requested_addr, size_t size, int prot, int flags,
 		sys_flags |= MAP_PRIVATE;
 	if (flags & RTE_MAP_FORCE_ADDRESS)
 		sys_flags |= MAP_FIXED;
+	if (flags & RTE_MAP_FORCE_ADDRESS_NOREPLACE)
+		sys_flags |= EAL_FIXED_NOREPLACE;
 
 	return mem_map(requested_addr, size, sys_prot, sys_flags, fd, offset);
 }
-- 
2.47.2