Re: [dpdk-dev] [PATCH v2] pci: keep API compatibility with mmap values

["Ma, LihongX" <lihongx.ma@intel.com>]

Tested-by:ma,lhong<lihongx.ma@intel.com>

Regards,
Ma,lihong

-----Original Message-----
From: dev <dev-bounces@dpdk.org> On Behalf Of Thomas Monjalon
Sent: Saturday, July 11, 2020 4:41 AM
To: dev@dpdk.org
Cc: david.marchand@redhat.com; Yigit, Ferruh <ferruh.yigit@intel.com>; grive@u256.net; Zhang, AlvinX <alvinx.zhang@intel.com>; Xing, Beilei <beilei.xing@intel.com>; Guo, Jia <jia.guo@intel.com>; Burakov, Anatoly <anatoly.burakov@intel.com>; Richardson, Bruce <bruce.richardson@intel.com>; dmitry.kozliuk@gmail.com; navasile@linux.microsoft.com; dmitrym@microsoft.com; Kadam, Pallavi <pallavi.kadam@intel.com>; talshn@mellanox.com
Subject: [dpdk-dev] [PATCH v2] pci: keep API compatibility with mmap values

The function pci_map_resource() returns MAP_FAILED in case of error.
When replacing the call to mmap() by rte_mem_map(), the error code became NULL, breaking the API.
This function is probably not used outside of DPDK, but it is still a problem for two reasons:
	- the deprecation process was not followed
	- the Linux function pci_vfio_mmap_bar() is broken for i40e

The error code is reverted to the Unix value MAP_FAILED.
Windows needs to define this special value (-1 as in Unix).
After proper deprecation process, the API could be changed again if really needed.

Because of the switch from mmap() to rte_mem_map(), another part of the API was changed: "int additional_flags"
are defined as "additional flags for the mapping range"
without mentioning it was directly used in mmap().
Currently it is directly used in rte_mem_map(), that's why the values rte_map_flags must be mapped (sic) on the mmap ones in case of Unix OS.

These are side effects of a badly defined API using Unix values.

Bugzilla ID: 503
Fixes: 2fd3567e5425 ("pci: use OS generic memory mapping functions")
Cc: talshn@mellanox.com

Reported-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---
v2: move MAP_FAILED from sys/mman.h to rte_os.h
---
 drivers/bus/pci/bsd/pci.c               |  2 +-
 drivers/bus/pci/linux/pci_uio.c         |  2 +-
 drivers/bus/pci/linux/pci_vfio.c        |  4 ++--
 drivers/bus/pci/pci_common_uio.c        |  2 +-
 lib/librte_eal/include/rte_eal_paging.h | 10 ++++++++++  lib/librte_eal/windows/include/rte_os.h |  6 ++++++
 lib/librte_pci/rte_pci.c                |  1 +
 lib/librte_pci/rte_pci.h                |  2 +-
 8 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/bus/pci/bsd/pci.c b/drivers/bus/pci/bsd/pci.c index 8bc473eb9a..6ec27b4b5b 100644
--- a/drivers/bus/pci/bsd/pci.c
+++ b/drivers/bus/pci/bsd/pci.c
@@ -192,7 +192,7 @@ pci_uio_map_resource_by_index(struct rte_pci_device *dev, int res_idx,
 	mapaddr = pci_map_resource(NULL, fd, (off_t)offset,
 			(size_t)dev->mem_resource[res_idx].len, 0);
 	close(fd);
-	if (mapaddr == NULL)
+	if (mapaddr == MAP_FAILED)
 		goto error;
 
 	maps[map_idx].phaddr = dev->mem_resource[res_idx].phys_addr;
diff --git a/drivers/bus/pci/linux/pci_uio.c b/drivers/bus/pci/linux/pci_uio.c index b622001539..097dc19225 100644
--- a/drivers/bus/pci/linux/pci_uio.c
+++ b/drivers/bus/pci/linux/pci_uio.c
@@ -345,7 +345,7 @@ pci_uio_map_resource_by_index(struct rte_pci_device *dev, int res_idx,
 	mapaddr = pci_map_resource(pci_map_addr, fd, 0,
 			(size_t)dev->mem_resource[res_idx].len, 0);
 	close(fd);
-	if (mapaddr == NULL)
+	if (mapaddr == MAP_FAILED)
 		goto error;
 
 	pci_map_addr = RTE_PTR_ADD(mapaddr,
diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index fdeb9a8caf..07e072e13f 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -566,7 +566,7 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct mapped_pci_resource *vfio_res,
 		}
 
 		/* if there's a second part, try to map it */
-		if (map_addr != NULL
+		if (map_addr != MAP_FAILED
 			&& memreg[1].offset && memreg[1].size) {
 			void *second_addr = RTE_PTR_ADD(bar_addr,
 						(uintptr_t)(memreg[1].offset -
@@ -578,7 +578,7 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct mapped_pci_resource *vfio_res,
 							RTE_MAP_FORCE_ADDRESS);
 		}
 
-		if (map_addr == NULL) {
+		if (map_addr == NULL || map_addr == MAP_FAILED) {
 			munmap(bar_addr, bar->size);
 			bar_addr = MAP_FAILED;
 			RTE_LOG(ERR, EAL, "Failed to map pci BAR%d\n", diff --git a/drivers/bus/pci/pci_common_uio.c b/drivers/bus/pci/pci_common_uio.c
index 793dfd0a7c..f4dca9da91 100644
--- a/drivers/bus/pci/pci_common_uio.c
+++ b/drivers/bus/pci/pci_common_uio.c
@@ -58,7 +58,7 @@ pci_uio_map_secondary(struct rte_pci_device *dev)
 					"Cannot mmap device resource file %s to address: %p\n",
 					uio_res->maps[i].path,
 					uio_res->maps[i].addr);
-				if (mapaddr != NULL) {
+				if (mapaddr != MAP_FAILED) {
 					/* unmap addrs correctly mapped */
 					for (j = 0; j < i; j++)
 						pci_unmap_resource(
diff --git a/lib/librte_eal/include/rte_eal_paging.h b/lib/librte_eal/include/rte_eal_paging.h
index ed98e70e9e..429f896c8c 100644
--- a/lib/librte_eal/include/rte_eal_paging.h
+++ b/lib/librte_eal/include/rte_eal_paging.h
@@ -3,6 +3,9 @@
  */
 
 #include <stdint.h>
+#ifndef RTE_EXEC_ENV_WINDOWS
+#include <sys/mman.h>
+#endif
 
 #include <rte_compat.h>
 
@@ -22,6 +25,7 @@ enum rte_mem_prot {
 
 /** Additional flags for memory mapping. */  enum rte_map_flags {
+#ifdef RTE_EXEC_ENV_WINDOWS
 	/** Changes to the mapped memory are visible to other processes. */
 	RTE_MAP_SHARED = 1 << 0,
 	/** Mapping is not backed by a regular file. */ @@ -35,6 +39,12 @@ enum rte_map_flags {
 	 * it is not required to do so, thus mapping with this flag may fail.
 	 */
 	RTE_MAP_FORCE_ADDRESS = 1 << 3
+#else /* map mmap flags because they are exposed in pci_map_resource() API */
+	RTE_MAP_SHARED = MAP_SHARED,
+	RTE_MAP_ANONYMOUS = MAP_ANONYMOUS,
+	RTE_MAP_PRIVATE = MAP_PRIVATE,
+	RTE_MAP_FORCE_ADDRESS = MAP_FIXED,
+#endif
 };
 
 /**
diff --git a/lib/librte_eal/windows/include/rte_os.h b/lib/librte_eal/windows/include/rte_os.h
index 569ed92d51..2881bf2224 100644
--- a/lib/librte_eal/windows/include/rte_os.h
+++ b/lib/librte_eal/windows/include/rte_os.h
@@ -25,6 +25,12 @@ extern "C" {
 #define PATH_MAX _MAX_PATH
 #endif
 
+/* sys/mman.h
+ * The syscall mmap does not exist on Windows,
+ * but this error code is used in a badly defined DPDK API for PCI mapping.
+ */
+#define MAP_FAILED ((void *) -1)
+
 #define sleep(x) Sleep(1000 * (x))
 
 #define strerror_r(a, b, c) strerror_s(b, c, a) diff --git a/lib/librte_pci/rte_pci.c b/lib/librte_pci/rte_pci.c index d8272b9076..1d1cbc75ac 100644
--- a/lib/librte_pci/rte_pci.c
+++ b/lib/librte_pci/rte_pci.c
@@ -163,6 +163,7 @@ pci_map_resource(void *requested_addr, int fd, off_t offset, size_t size,
 			__func__, fd, requested_addr, size,
 			(unsigned long long)offset,
 			rte_strerror(rte_errno), mapaddr);
+		mapaddr = MAP_FAILED; /* API uses mmap error code */
 	} else
 		RTE_LOG(DEBUG, EAL, "  PCI memory mapped at %p\n", mapaddr);
 
diff --git a/lib/librte_pci/rte_pci.h b/lib/librte_pci/rte_pci.h index 104b2bb858..a03235da1f 100644
--- a/lib/librte_pci/rte_pci.h
+++ b/lib/librte_pci/rte_pci.h
@@ -160,7 +160,7 @@ int rte_pci_addr_parse(const char *str, struct rte_pci_addr *addr);
  *      The additional flags for the mapping range.
  * @return
  *   - On success, the function returns a pointer to the mapped area.
- *   - On error, NULL is returned.
+ *   - On error, MAP_FAILED is returned.
  */
 void *pci_map_resource(void *requested_addr, int fd, off_t offset,
 		size_t size, int additional_flags);
--
2.27.0