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);