1 files changed, 89 insertions, 0 deletions
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 24a76de49f41..2a42add7f563 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -60,3 +60,92 @@ EXPORT_SYMBOL(pci_bus_read_config_dword);
 EXPORT_SYMBOL(pci_bus_write_config_byte);
 EXPORT_SYMBOL(pci_bus_write_config_word);
 EXPORT_SYMBOL(pci_bus_write_config_dword);
+
+static u32 pci_user_cached_config(struct pci_dev *dev, int pos)
+{
+	u32 data;
+
+	data = dev->saved_config_space[pos/sizeof(dev->saved_config_space[0])];
+	data >>= (pos % sizeof(dev->saved_config_space[0])) * 8;
+	return data;
+}
+
+#define PCI_USER_READ_CONFIG(size,type)					\
+int pci_user_read_config_##size						\
+	(struct pci_dev *dev, int pos, type *val)			\
+{									\
+	unsigned long flags;						\
+	int ret = 0;							\
+	u32 data = -1;							\
+	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
+	spin_lock_irqsave(&pci_lock, flags);				\
+	if (likely(!dev->block_ucfg_access))				\
+		ret = dev->bus->ops->read(dev->bus, dev->devfn,		\
+					pos, sizeof(type), &data);	\
+	else if (pos < sizeof(dev->saved_config_space))			\
+		data = pci_user_cached_config(dev, pos); 		\
+	spin_unlock_irqrestore(&pci_lock, flags);			\
+	*val = (type)data;						\
+	return ret;							\
+}
+
+#define PCI_USER_WRITE_CONFIG(size,type)				\
+int pci_user_write_config_##size					\
+	(struct pci_dev *dev, int pos, type val)			\
+{									\
+	unsigned long flags;						\
+	int ret = -EIO;							\
+	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
+	spin_lock_irqsave(&pci_lock, flags);				\
+	if (likely(!dev->block_ucfg_access))				\
+		ret = dev->bus->ops->write(dev->bus, dev->devfn,	\
+					pos, sizeof(type), val);	\
+	spin_unlock_irqrestore(&pci_lock, flags);			\
+	return ret;							\
+}
+
+PCI_USER_READ_CONFIG(byte, u8)
+PCI_USER_READ_CONFIG(word, u16)
+PCI_USER_READ_CONFIG(dword, u32)
+PCI_USER_WRITE_CONFIG(byte, u8)
+PCI_USER_WRITE_CONFIG(word, u16)
+PCI_USER_WRITE_CONFIG(dword, u32)
+
+/**
+ * pci_block_user_cfg_access - Block userspace PCI config reads/writes
+ * @dev:	pci device struct
+ *
+ * This function blocks any userspace PCI config accesses from occurring.
+ * When blocked, any writes will be bit bucketed and reads will return the
+ * data saved using pci_save_state for the first 64 bytes of config
+ * space and return 0xff for all other config reads.
+ **/
+void pci_block_user_cfg_access(struct pci_dev *dev)
+{
+	unsigned long flags;
+
+	pci_save_state(dev);
+
+	/* spinlock to synchronize with anyone reading config space now */
+	spin_lock_irqsave(&pci_lock, flags);
+	dev->block_ucfg_access = 1;
+	spin_unlock_irqrestore(&pci_lock, flags);
+}
+EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);
+
+/**
+ * pci_unblock_user_cfg_access - Unblock userspace PCI config reads/writes
+ * @dev:	pci device struct
+ *
+ * This function allows userspace PCI config accesses to resume.
+ **/
+void pci_unblock_user_cfg_access(struct pci_dev *dev)
+{
+	unsigned long flags;
+
+	/* spinlock to synchronize with anyone reading saved config space */
+	spin_lock_irqsave(&pci_lock, flags);
+	dev->block_ucfg_access = 0;
+	spin_unlock_irqrestore(&pci_lock, flags);
+}
+EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);