diff options
| -rw-r--r-- | drivers/pci/access.c | 75 |
1 files changed, 47 insertions, 28 deletions
diff --git a/drivers/pci/access.c b/drivers/pci/access.c index ea16805a153..73a58c73d52 100644 --- a/drivers/pci/access.c +++ b/drivers/pci/access.c @@ -1,6 +1,7 @@ #include <linux/pci.h> #include <linux/module.h> #include <linux/ioport.h> +#include <linux/wait.h> #include "pci.h" @@ -63,30 +64,42 @@ 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; +/* + * The following routines are to prevent the user from accessing PCI config + * space when it's unsafe to do so. Some devices require this during BIST and + * we're required to prevent it during D-state transitions. + * + * We have a bit per device to indicate it's blocked and a global wait queue + * for callers to sleep on until devices are unblocked. + */ +static DECLARE_WAIT_QUEUE_HEAD(pci_ucfg_wait); - data = dev->saved_config_space[pos/sizeof(dev->saved_config_space[0])]; - data >>= (pos % sizeof(dev->saved_config_space[0])) * 8; - return data; +static noinline void pci_wait_ucfg(struct pci_dev *dev) +{ + DECLARE_WAITQUEUE(wait, current); + + __add_wait_queue(&pci_ucfg_wait, &wait); + do { + set_current_state(TASK_UNINTERRUPTIBLE); + spin_unlock_irq(&pci_lock); + schedule(); + spin_lock_irq(&pci_lock); + } while (dev->block_ucfg_access); + __remove_wait_queue(&pci_ucfg_wait, &wait); } #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, \ + spin_lock_irq(&pci_lock); \ + if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev); \ + 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); \ + spin_unlock_irq(&pci_lock); \ *val = (type)data; \ return ret; \ } @@ -95,14 +108,13 @@ int pci_user_read_config_##size \ 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, \ + spin_lock_irq(&pci_lock); \ + if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev); \ + ret = dev->bus->ops->write(dev->bus, dev->devfn, \ pos, sizeof(type), val); \ - spin_unlock_irqrestore(&pci_lock, flags); \ + spin_unlock_irq(&pci_lock); \ return ret; \ } @@ -117,21 +129,23 @@ 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. - **/ + * When user access is blocked, any reads or writes to config space will + * sleep until access is unblocked again. We don't allow nesting of + * block/unblock calls. + */ void pci_block_user_cfg_access(struct pci_dev *dev) { unsigned long flags; + int was_blocked; - pci_save_state(dev); - - /* spinlock to synchronize with anyone reading config space now */ spin_lock_irqsave(&pci_lock, flags); + was_blocked = dev->block_ucfg_access; dev->block_ucfg_access = 1; spin_unlock_irqrestore(&pci_lock, flags); + + /* If we BUG() inside the pci_lock, we're guaranteed to hose + * the machine */ + BUG_ON(was_blocked); } EXPORT_SYMBOL_GPL(pci_block_user_cfg_access); @@ -140,14 +154,19 @@ EXPORT_SYMBOL_GPL(pci_block_user_cfg_access); * @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); + + /* This indicates a problem in the caller, but we don't need + * to kill them, unlike a double-block above. */ + WARN_ON(!dev->block_ucfg_access); + dev->block_ucfg_access = 0; + wake_up_all(&pci_ucfg_wait); spin_unlock_irqrestore(&pci_lock, flags); } EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access); |