[1/2] PCI: Add interfaces to store and load the device saved state

Commit Message

Alex Williamson April 15, 2011, 7:54 p.m. UTC

For KVM device assignment, we'd like to save off the state of a device
prior to passing it to the guest and restore it later.  We also want
to allow pci_reset_funciton() to be called while the device is owned
by the guest.  This however overwrites and invalidates the struct pci_dev
buffers, so we can't just manually call save and restore.  Add generic
interfaces for the saved state to be stored into a buffer and reloaded
back into struct pci_dev at a later time.

Signed-off-by: Alex Williamson <[e-mail]>
---

 drivers/pci/pci.c   |   94 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pci.h |    3 ++
 2 files changed, 97 insertions(+), 0 deletions(-)


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Patch

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2472e71..2b00354 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -975,6 +975,100 @@  void pci_restore_state(struct pci_dev *dev)
 	dev->state_saved = false;
 }
 
+struct pci_state {
+	u32 config_space[16];
+	u16 pcie_state[PCI_EXP_SAVE_REGS];
+	u16 pcix_state[1];
+};
+
+/**
+ * pci_store_saved_state - Store the device saved state into a buffer
+ * @dev: - PCI device that we're dealing with
+ *
+ * Returns an opaque buffer containing the device saved state.
+ * NULL if no state or error.
+ */
+void *pci_store_saved_state(struct pci_dev *dev)
+{
+	struct pci_state *state;
+	struct pci_cap_saved_state *cap_state;
+	int pos;
+
+	if (!dev->state_saved)
+		return NULL;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return NULL;
+
+	memcpy(state->config_space, dev->saved_config_space,
+	       sizeof(state->config_space));
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+	cap_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
+	if (cap_state && pos)
+		memcpy(state->pcie_state, cap_state->data,
+		       sizeof(state->pcie_state));
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+	cap_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
+	if (cap_state && pos)
+		memcpy(state->pcix_state, cap_state->data,
+		       sizeof(state->pcix_state));
+
+	return state;
+}
+EXPORT_SYMBOL_GPL(pci_store_saved_state);
+
+/**
+ * pci_load_saved_state - Load the device saved state from buffer
+ * @dev: - PCI device that we're dealing with
+ * @buf: - Saved state returned from pci_store_saved_state()
+ */
+void pci_load_saved_state(struct pci_dev *dev, void *buf)
+{
+	struct pci_state *state = buf;
+	struct pci_cap_saved_state *cap_state;
+	int pos;
+
+	if (!state) {
+		dev->state_saved = false;
+		return;
+	}
+
+	memcpy(dev->saved_config_space, state->config_space,
+	       sizeof(state->config_space));
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+	cap_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
+	if (cap_state && pos)
+		memcpy(cap_state->data, state->pcie_state,
+		       sizeof(state->pcie_state));
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
+	cap_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
+	if (cap_state && pos)
+		memcpy(cap_state->data, state->pcix_state,
+		       sizeof(state->pcix_state));
+
+	dev->state_saved = true;
+}
+EXPORT_SYMBOL_GPL(pci_load_saved_state);
+
+/**
+ * pci_load_and_free_saved_state - Load the device saved state from buffer
+ *				   and free the buffer
+ * @dev: - PCI device that we're dealing with
+ * @buf: - Pointer to saved state returned from pci_store_saved_state()
+ */
+void pci_load_and_free_saved_state(struct pci_dev *dev, void **buf)
+{
+	pci_load_saved_state(dev, *buf);
+	kfree(*buf);
+	*buf = NULL;
+}
+EXPORT_SYMBOL_GPL(pci_load_and_free_saved_state);
+
 static int do_pci_enable_device(struct pci_dev *dev, int bars)
 {
 	int err;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 96f70d7..67ce42a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -807,6 +807,9 @@  size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size);
 /* Power management related routines */
 int pci_save_state(struct pci_dev *dev);
 void pci_restore_state(struct pci_dev *dev);
+void *pci_store_saved_state(struct pci_dev *dev);
+void pci_load_saved_state(struct pci_dev *dev, void *buf);
+void pci_load_and_free_saved_state(struct pci_dev *dev, void **buf);
 int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state);
 int pci_set_power_state(struct pci_dev *dev, pci_power_t state);
 pci_power_t pci_choose_state(struct pci_dev *dev, pm_message_t state);