PCI/IOV: Add pci_resource_num_to_vf_bar() to convert VF BAR number to/from IOV resource

There are multiple places where conversions between IOV resources and
corresponding VF BAR numbers are done.

Extract the logic to pci_resource_num_from_vf_bar() and
pci_resource_num_to_vf_bar() helpers.

Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patch.msgid.link/20250702093522.518099-3-michal.winiarski@intel.com

Author: mwiniars

drivers/pci/iov.c

@@ -151,7 +151,7 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
 	if (!dev->is_physfn)
 		return 0;
 
-	return dev->sriov->barsz[resno - PCI_IOV_RESOURCES];
+	return dev->sriov->barsz[pci_resource_num_to_vf_bar(resno)];
 }
 
 static void pci_read_vf_config_common(struct pci_dev *virtfn)
@@ -342,12 +342,14 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 	virtfn->multifunction = 0;
 
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
-		res = &dev->resource[i + PCI_IOV_RESOURCES];
+		int idx = pci_resource_num_from_vf_bar(i);
+
+		res = &dev->resource[idx];
 		if (!res->parent)
 			continue;
 		virtfn->resource[i].name = pci_name(virtfn);
 		virtfn->resource[i].flags = res->flags;
-		size = pci_iov_resource_size(dev, i + PCI_IOV_RESOURCES);
+		size = pci_iov_resource_size(dev, idx);
 		resource_set_range(&virtfn->resource[i],
 				   res->start + size * id, size);
 		rc = request_resource(res, &virtfn->resource[i]);
@@ -644,8 +646,10 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 
 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
-		bars |= (1 << (i + PCI_IOV_RESOURCES));
-		res = &dev->resource[i + PCI_IOV_RESOURCES];
+		int idx = pci_resource_num_from_vf_bar(i);
+
+		bars |= (1 << idx);
+		res = &dev->resource[idx];
 		if (res->parent)
 			nres++;
 	}
@@ -811,8 +815,10 @@ static int sriov_init(struct pci_dev *dev, int pos)
 
 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
-		res = &dev->resource[i + PCI_IOV_RESOURCES];
-		res_name = pci_resource_name(dev, i + PCI_IOV_RESOURCES);
+		int idx = pci_resource_num_from_vf_bar(i);
+
+		res = &dev->resource[idx];
+		res_name = pci_resource_name(dev, idx);
 
 		/*
 		 * If it is already FIXED, don't change it, something
@@ -871,7 +877,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
 	dev->is_physfn = 0;
 failed:
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
-		res = &dev->resource[i + PCI_IOV_RESOURCES];
+		res = &dev->resource[pci_resource_num_from_vf_bar(i)];
 		res->flags = 0;
 	}
 
@@ -933,7 +939,7 @@ static void sriov_restore_state(struct pci_dev *dev)
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, ctrl);
 
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++)
-		pci_update_resource(dev, i + PCI_IOV_RESOURCES);
+		pci_update_resource(dev, pci_resource_num_from_vf_bar(i));
 
 	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
 	pci_iov_set_numvfs(dev, iov->num_VFs);
@@ -999,7 +1005,7 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno)
 {
 	struct pci_sriov *iov = dev->is_physfn ? dev->sriov : NULL;
 	struct resource *res = pci_resource_n(dev, resno);
-	int vf_bar = resno - PCI_IOV_RESOURCES;
+	int vf_bar = pci_resource_num_to_vf_bar(resno);
 	struct pci_bus_region region;
 	u16 cmd;
 	u32 new;

drivers/pci/pci.h

@@ -722,6 +722,14 @@ static inline bool pci_resource_is_iov(int resno)
 {
 	return resno >= PCI_IOV_RESOURCES && resno <= PCI_IOV_RESOURCE_END;
 }
+static inline int pci_resource_num_from_vf_bar(int resno)
+{
+	return resno + PCI_IOV_RESOURCES;
+}
+static inline int pci_resource_num_to_vf_bar(int resno)
+{
+	return resno - PCI_IOV_RESOURCES;
+}
 extern const struct attribute_group sriov_pf_dev_attr_group;
 extern const struct attribute_group sriov_vf_dev_attr_group;
 #else
@@ -750,6 +758,16 @@ static inline bool pci_resource_is_iov(int resno)
 {
 	return false;
 }
+static inline int pci_resource_num_from_vf_bar(int resno)
+{
+	WARN_ON_ONCE(1);
+	return -ENODEV;
+}
+static inline int pci_resource_num_to_vf_bar(int resno)
+{
+	WARN_ON_ONCE(1);
+	return -ENODEV;
+}
 #endif /* CONFIG_PCI_IOV */
 
 #ifdef CONFIG_PCIE_TPH

drivers/pci/setup-bus.c

@@ -1888,7 +1888,8 @@ static int iov_resources_unassigned(struct pci_dev *dev, void *data)
 	bool *unassigned = data;
 
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
-		struct resource *r = &dev->resource[i + PCI_IOV_RESOURCES];
+		int idx = pci_resource_num_from_vf_bar(i);
+		struct resource *r = &dev->resource[idx];
 		struct pci_bus_region region;
 
 		/* Not assigned or rejected by kernel? */