[PATCH v19 22/26] vfio: decouple device setup from bus concerns

[David Marchand <david.marchand@redhat.com>]

From: Anatoly Burakov <anatoly.burakov@intel.com>

Change the return semantics of dev_vfio_setup_device and
dev_vfio_get_group_num to be more consistent with standard error
handling conventions.

Previously, these functions returned positive values (1 or >0) to
indicate that a device is not managed by VFIO. This convention was
inherited from PCI bus semantics where positive return means "skip
this device", but VFIO should not follow bus-specific conventions.

Now both functions return -1 with rte_errno set to ENODEV when the
device is not managed by VFIO. This makes error handling more
consistent and allows callers to distinguish between "not a VFIO
device" (ENODEV) and actual errors.

All driver call sites have been updated to check for rte_errno ==
ENODEV and convert it to the bus-specific "skip" return value (1)
where appropriate.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
---
 drivers/bus/cdx/cdx_vfio.c               | 13 ++++++++--
 drivers/bus/fslmc/fslmc_vfio.c           |  4 +--
 drivers/bus/pci/linux/pci_vfio.c         | 13 ++++++++--
 drivers/crypto/bcmfs/bcmfs_vfio.c        |  9 +++++--
 drivers/net/nbl/nbl_common/nbl_userdev.c |  2 +-
 lib/eal/linux/eal_vfio.c                 | 33 +++++++-----------------
 lib/eal/linux/include/dev_vfio.h         |  4 +--
 7 files changed, 43 insertions(+), 35 deletions(-)

diff --git a/drivers/bus/cdx/cdx_vfio.c b/drivers/bus/cdx/cdx_vfio.c
index 0e9445bff8..ff09f0c810 100644
--- a/drivers/bus/cdx/cdx_vfio.c
+++ b/drivers/bus/cdx/cdx_vfio.c
@@ -22,6 +22,7 @@
 
 #include <eal_export.h>
 #include <rte_eal_paging.h>
+#include <rte_errno.h>
 #include <rte_malloc.h>
 #include <dev_vfio.h>
 
@@ -402,8 +403,12 @@ cdx_vfio_map_resource_primary(struct rte_cdx_device *dev)
 
 	ret = dev_vfio_setup_device(RTE_CDX_BUS_DEVICES_PATH, dev_name,
 				    &vfio_dev_fd);
-	if (ret)
+	if (ret < 0) {
+		/* Device not managed by VFIO - skip */
+		if (rte_errno == ENODEV)
+			ret = 1;
 		return ret;
+	}
 
 	ret = dev_vfio_get_device_info(vfio_dev_fd, &device_info);
 	if (ret)
@@ -514,8 +519,12 @@ cdx_vfio_map_resource_secondary(struct rte_cdx_device *dev)
 	}
 
 	ret = dev_vfio_setup_device(RTE_CDX_BUS_DEVICES_PATH, dev_name, &vfio_dev_fd);
-	if (ret)
+	if (ret < 0) {
+		/* Device not managed by VFIO - skip */
+		if (rte_errno == ENODEV)
+			ret = 1;
 		return ret;
+	}
 
 	ret = dev_vfio_get_device_info(vfio_dev_fd, &device_info);
 	if (ret)
diff --git a/drivers/bus/fslmc/fslmc_vfio.c b/drivers/bus/fslmc/fslmc_vfio.c
index 153e6112db..c2b6ac1f3f 100644
--- a/drivers/bus/fslmc/fslmc_vfio.c
+++ b/drivers/bus/fslmc/fslmc_vfio.c
@@ -376,9 +376,9 @@ fslmc_get_group_id(const char *group_name,
 	/* get group number */
 	ret = dev_vfio_get_group_num(SYSFS_FSL_MC_DEVICES,
 			group_name, groupid);
-	if (ret <= 0) {
+	if (ret < 0) {
 		DPAA2_BUS_ERR("Find %s IOMMU group", group_name);
-		if (ret < 0)
+		if (rte_errno != ENODEV)
 			return ret;
 
 		return -EIO;
diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index a4bb1475e8..5af4302d62 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -20,6 +20,7 @@
 #include <rte_malloc.h>
 #include <dev_vfio.h>
 #include <rte_eal.h>
+#include <rte_errno.h>
 #include <bus_driver.h>
 #include <rte_spinlock.h>
 #include <rte_tailq.h>
@@ -753,8 +754,12 @@ pci_vfio_map_resource_primary(struct rte_pci_device *dev)
 			loc->domain, loc->bus, loc->devid, loc->function);
 
 	ret = dev_vfio_setup_device(rte_pci_get_sysfs_path(), pci_addr, &vfio_dev_fd);
-	if (ret)
+	if (ret < 0) {
+		/* Device not managed by VFIO - skip */
+		if (rte_errno == ENODEV)
+			ret = 1;
 		return ret;
+	}
 
 	ret = dev_vfio_get_device_info(vfio_dev_fd, &device_info);
 	if (ret)
@@ -965,8 +970,12 @@ pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
 	}
 
 	ret = dev_vfio_setup_device(rte_pci_get_sysfs_path(), pci_addr, &vfio_dev_fd);
-	if (ret)
+	if (ret < 0) {
+		/* Device not managed by VFIO - skip */
+		if (rte_errno == ENODEV)
+			ret = 1;
 		return ret;
+	}
 
 	ret = dev_vfio_get_device_info(vfio_dev_fd, &device_info);
 	if (ret)
diff --git a/drivers/crypto/bcmfs/bcmfs_vfio.c b/drivers/crypto/bcmfs/bcmfs_vfio.c
index ad244d9756..92c8472953 100644
--- a/drivers/crypto/bcmfs/bcmfs_vfio.c
+++ b/drivers/crypto/bcmfs/bcmfs_vfio.c
@@ -9,6 +9,7 @@
 #include <sys/mman.h>
 #include <sys/ioctl.h>
 
+#include <rte_errno.h>
 #include <dev_vfio.h>
 
 #include "bcmfs_device.h"
@@ -26,8 +27,12 @@ vfio_map_dev_obj(const char *path, const char *dev_obj,
 	struct vfio_region_info reg_info = { .argsz = sizeof(reg_info) };
 
 	ret = dev_vfio_setup_device(path, dev_obj, dev_fd);
-	if (ret) {
-		BCMFS_LOG(ERR, "VFIO Setting for device failed");
+	if (ret < 0) {
+		/* Device not managed by VFIO - skip */
+		if (rte_errno == ENODEV)
+			ret = 1;
+		else
+			BCMFS_LOG(ERR, "VFIO Setting for device failed");
 		return ret;
 	}
 
diff --git a/drivers/net/nbl/nbl_common/nbl_userdev.c b/drivers/net/nbl/nbl_common/nbl_userdev.c
index 91b7c8006f..295c617d9d 100644
--- a/drivers/net/nbl/nbl_common/nbl_userdev.c
+++ b/drivers/net/nbl/nbl_common/nbl_userdev.c
@@ -430,7 +430,7 @@ static int nbl_mdev_map_device(struct nbl_adapter *adapter)
 		 "%s/%s/", rte_pci_get_sysfs_path(), dev_name);
 
 	ret = dev_vfio_get_group_num(pathname, dev_name, &common->iommu_group_num);
-	if (ret <= 0) {
+	if (ret < 0) {
 		NBL_LOG(ERR, "nbl vfio group number failed");
 		return -1;
 	}
diff --git a/lib/eal/linux/eal_vfio.c b/lib/eal/linux/eal_vfio.c
index d4a165464f..fe60c57fc5 100644
--- a/lib/eal/linux/eal_vfio.c
+++ b/lib/eal/linux/eal_vfio.c
@@ -33,6 +33,7 @@
  * rte_errno convention:
  *
  * - EINVAL: invalid parameters
+ * - ENODEV: device not managed by VFIO
  */
 
 /* per-process VFIO config */
@@ -771,14 +772,6 @@ dev_vfio_setup_device(const char *sysfs_base, const char *dev_addr, int *vfio_de
 
 	/* get group number */
 	ret = dev_vfio_get_group_num(sysfs_base, dev_addr, &iommu_group_num);
-	if (ret == 0) {
-		EAL_LOG(NOTICE,
-				"%s not managed by VFIO driver, skipping",
-				dev_addr);
-		return 1;
-	}
-
-	/* if negative, something failed */
 	if (ret < 0)
 		return -1;
 
@@ -792,10 +785,8 @@ dev_vfio_setup_device(const char *sysfs_base, const char *dev_addr, int *vfio_de
 	 * isn't managed by VFIO
 	 */
 	if (vfio_group_fd == -ENOENT) {
-		EAL_LOG(NOTICE,
-				"%s not managed by VFIO driver, skipping",
-				dev_addr);
-		return 1;
+		rte_errno = ENODEV;
+		return -1;
 	}
 
 	/*
@@ -1013,11 +1004,9 @@ dev_vfio_release_device(const char *sysfs_base, const char *dev_addr,
 
 	/* get group number */
 	ret = dev_vfio_get_group_num(sysfs_base, dev_addr, &iommu_group_num);
-	if (ret <= 0) {
+	if (ret < 0) {
 		EAL_LOG(WARNING, "%s not managed by VFIO driver",
 			dev_addr);
-		/* This is an error at this point. */
-		ret = -1;
 		goto out;
 	}
 
@@ -1304,8 +1293,7 @@ dev_vfio_get_container_fd(void)
 
 RTE_EXPORT_INTERNAL_SYMBOL(dev_vfio_get_group_num)
 int
-dev_vfio_get_group_num(const char *sysfs_base,
-		const char *dev_addr, int *iommu_group_num)
+dev_vfio_get_group_num(const char *sysfs_base, const char *dev_addr, int *iommu_group_num)
 {
 	char linkname[PATH_MAX];
 	char filename[PATH_MAX];
@@ -1330,8 +1318,10 @@ dev_vfio_get_group_num(const char *sysfs_base,
 	ret = readlink(linkname, filename, sizeof(filename));
 
 	/* if the link doesn't exist, no VFIO for us */
-	if (ret < 0)
-		return 0;
+	if (ret < 0) {
+		rte_errno = ENODEV;
+		return -1;
+	}
 
 	ret = rte_strsplit(filename, sizeof(filename),
 			tok, RTE_DIM(tok), '/');
@@ -1351,7 +1341,7 @@ dev_vfio_get_group_num(const char *sysfs_base,
 		return -1;
 	}
 
-	return 1;
+	return 0;
 }
 
 static int
@@ -1645,9 +1635,6 @@ dev_vfio_container_assign_device(int vfio_container_fd, const char *sysfs_base,
 	if (ret < 0) {
 		EAL_LOG(ERR, "Cannot get IOMMU group number for device %s", dev_addr);
 		return -1;
-	} else if (ret == 0) {
-		EAL_LOG(ERR, "Device %s is not assigned to any IOMMU group", dev_addr);
-		return -1;
 	}
 
 	ret = vfio_container_group_bind(vfio_container_fd, iommu_group_num);
diff --git a/lib/eal/linux/include/dev_vfio.h b/lib/eal/linux/include/dev_vfio.h
index b3bf1ed7eb..4e2c21ae89 100644
--- a/lib/eal/linux/include/dev_vfio.h
+++ b/lib/eal/linux/include/dev_vfio.h
@@ -62,7 +62,6 @@ enum dev_vfio_module {
  *
  * @return
  *   0 on success.
- *   >1 if the device cannot be managed this way.
  *   <0 on failure, rte_errno is set.
  *
  * Possible rte_errno values include:
@@ -159,8 +158,7 @@ int dev_vfio_noiommu_is_enabled(void);
  *   Pointer to where IOMMU group number will be stored.
  *
  * @return
- *  >0 on success
- *   0 for non-existent group or VFIO
+ *   0 on success.
  *   <0 on failure, rte_errno is set.
  *
  * Possible rte_errno values include:
-- 
2.54.0