PCI/VPD: Add pci_read/write_vpd_any()

In certain cases we need a variant of pci_read_vpd()/pci_write_vpd() that
does not check against dev->vpd.len. Such cases are:

  - Reading VPD if dev->vpd.len isn't set yet (in pci_vpd_size())

  - Devices that map non-VPD information to arbitrary places in VPD address
    space (example: Chelsio T3 EEPROM write-protect flag)

Therefore add pci_read_vpd_any() and pci_write_vpd_any() that check against
PCI_VPD_MAX_SIZE only.

Link: https://lore.kernel.org/r/93ecce28-a158-f02a-d134-8afcaced8efe@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>

drivers/pci/vpd.c

@@ -156,9 +156,10 @@ static int pci_vpd_wait(struct pci_dev *dev, bool set)
 }
 
 static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
-			    void *arg)
+			    void *arg, bool check_size)
 {
 	struct pci_vpd *vpd = &dev->vpd;
+	unsigned int max_len = check_size ? vpd->len : PCI_VPD_MAX_SIZE;
 	int ret = 0;
 	loff_t end = pos + count;
 	u8 *buf = arg;
@@ -169,11 +170,11 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
 	if (pos < 0)
 		return -EINVAL;
 
-	if (pos > vpd->len)
+	if (pos >= max_len)
 		return 0;
 
-	if (end > vpd->len) {
+	if (end > max_len) {
-		end = vpd->len;
+		end = max_len;
 		count = end - pos;
 	}
 
@@ -217,9 +218,10 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
 }
 
 static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
-			     const void *arg)
+			     const void *arg, bool check_size)
 {
 	struct pci_vpd *vpd = &dev->vpd;
+	unsigned int max_len = check_size ? vpd->len : PCI_VPD_MAX_SIZE;
 	const u8 *buf = arg;
 	loff_t end = pos + count;
 	int ret = 0;
@@ -230,7 +232,7 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
 	if (pos < 0 || (pos & 3) || (count & 3))
 		return -EINVAL;
 
-	if (end > vpd->len)
+	if (end > max_len)
 		return -EINVAL;
 
 	if (mutex_lock_killable(&vpd->lock))
@@ -381,6 +383,24 @@ static int pci_vpd_find_info_keyword(const u8 *buf, unsigned int off,
 	return -ENOENT;
 }
 
+static ssize_t __pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf,
+			      bool check_size)
+{
+	ssize_t ret;
+
+	if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0) {
+		dev = pci_get_func0_dev(dev);
+		if (!dev)
+			return -ENODEV;
+
+		ret = pci_vpd_read(dev, pos, count, buf, check_size);
+		pci_dev_put(dev);
+		return ret;
+	}
+
+	return pci_vpd_read(dev, pos, count, buf, check_size);
+}
+
 /**
  * pci_read_vpd - Read one entry from Vital Product Data
  * @dev:	PCI device struct
@@ -389,6 +409,20 @@ static int pci_vpd_find_info_keyword(const u8 *buf, unsigned int off,
  * @buf:	pointer to where to store result
  */
 ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
+{
+	return __pci_read_vpd(dev, pos, count, buf, true);
+}
+EXPORT_SYMBOL(pci_read_vpd);
+
+/* Same, but allow to access any address */
+ssize_t pci_read_vpd_any(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
+{
+	return __pci_read_vpd(dev, pos, count, buf, false);
+}
+EXPORT_SYMBOL(pci_read_vpd_any);
+
+static ssize_t __pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count,
+			       const void *buf, bool check_size)
 {
 	ssize_t ret;
 
@@ -397,14 +431,13 @@ ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
 		if (!dev)
 			return -ENODEV;
 
-		ret = pci_vpd_read(dev, pos, count, buf);
+		ret = pci_vpd_write(dev, pos, count, buf, check_size);
 		pci_dev_put(dev);
 		return ret;
 	}
 
-	return pci_vpd_read(dev, pos, count, buf);
+	return pci_vpd_write(dev, pos, count, buf, check_size);
 }
-EXPORT_SYMBOL(pci_read_vpd);
 
 /**
  * pci_write_vpd - Write entry to Vital Product Data
@@ -415,22 +448,17 @@ EXPORT_SYMBOL(pci_read_vpd);
  */
 ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf)
 {
-	ssize_t ret;
+	return __pci_write_vpd(dev, pos, count, buf, true);
-
-	if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0) {
-		dev = pci_get_func0_dev(dev);
-		if (!dev)
-			return -ENODEV;
-
-		ret = pci_vpd_write(dev, pos, count, buf);
-		pci_dev_put(dev);
-		return ret;
-	}
-
-	return pci_vpd_write(dev, pos, count, buf);
 }
 EXPORT_SYMBOL(pci_write_vpd);
 
+/* Same, but allow to access any address */
+ssize_t pci_write_vpd_any(struct pci_dev *dev, loff_t pos, size_t count, const void *buf)
+{
+	return __pci_write_vpd(dev, pos, count, buf, false);
+}
+EXPORT_SYMBOL(pci_write_vpd_any);
+
 int pci_vpd_find_ro_info_keyword(const void *buf, unsigned int len,
 				 const char *kw, unsigned int *size)
 {

include/linux/pci.h

@@ -1350,6 +1350,8 @@ void pci_unlock_rescan_remove(void);
 /* Vital Product Data routines */
 ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
 ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
+ssize_t pci_read_vpd_any(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
+ssize_t pci_write_vpd_any(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
 
 /* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
 resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx);