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 and reloaded back into
struct pci_dev at a later time.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
drivers/pci/pci.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 4 ++
2 files changed, 102 insertions(+), 0 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 416930a..be423a6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -976,6 +976,104 @@ void pci_restore_state(struct pci_dev *dev)
dev->state_saved = false;
}
+struct pci_saved_state {
+ u32 config_space[16];
+ struct pci_cap_saved_data cap[0];
+};
+
+/**
+ * pci_store_saved_state - Allocate and return an opaque struct containing
+ * the device saved state.
+ * @dev: PCI device that we're dealing with
+ *
+ * Rerturn NULL if no state or error.
+ */
+struct pci_saved_state *pci_store_saved_state(struct pci_dev *dev)
+{
+ struct pci_saved_state *state;
+ struct pci_cap_saved_state *tmp;
+ struct pci_cap_saved_data *cap;
+ struct hlist_node *pos;
+ size_t size;
+
+ if (!dev->state_saved)
+ return NULL;
+
+ size = sizeof(*state) + sizeof(struct pci_cap_saved_data);
+
+ hlist_for_each_entry(tmp, pos, &dev->saved_cap_space, next)
+ size += sizeof(struct pci_cap_saved_data) + tmp->cap.size;
+
+ state = kzalloc(size, GFP_KERNEL);
+ if (!state)
+ return NULL;
+
+ memcpy(state->config_space, dev->saved_config_space,
+ sizeof(state->config_space));
+
+ cap = state->cap;
+ hlist_for_each_entry(tmp, pos, &dev->saved_cap_space, next) {
+ size_t len = sizeof(struct pci_cap_saved_data) + tmp->cap.size;
+ memcpy(cap, &tmp->cap, len);
+ cap = (struct pci_cap_saved_data *)((u8 *)cap + len);
+ }
+ /* Empty cap_save terminates list */
+
+ return state;
+}
+EXPORT_SYMBOL_GPL(pci_store_saved_state);
+
+/**
+ * pci_load_saved_state - Reload the provided save state into struct pci_dev.
+ * @dev: PCI device that we're dealing with
+ * @state: Saved state returned from pci_store_saved_state()
+ */
+int pci_load_saved_state(struct pci_dev *dev, struct pci_saved_state *state)
+{
+ struct pci_cap_saved_data *cap;
+
+ dev->state_saved = false;
+
+ if (!state)
+ return 0;
+
+ memcpy(dev->saved_config_space, state->config_space,
+ sizeof(state->config_space));
+
+ cap = state->cap;
+ while (cap->size) {
+ struct pci_cap_saved_state *tmp;
+
+ tmp = pci_find_saved_cap(dev, cap->cap_nr);
+ if (!tmp || tmp->cap.size != cap->size)
+ return -EINVAL;
+
+ memcpy(tmp->cap.data, cap->data, tmp->cap.size);
+ cap = (struct pci_cap_saved_data *)((u8 *)cap +
+ sizeof(struct pci_cap_saved_data) + cap->size);
+ }
+
+ dev->state_saved = true;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pci_load_saved_state);
+
+/**
+ * pci_load_and_free_saved_state - Reload the save state pointed to by state,
+ * and free the memory allocated for it.
+ * @dev: PCI device that we're dealing with
+ * @state: Pointer to saved state returned from pci_store_saved_state()
+ */
+int pci_load_and_free_saved_state(struct pci_dev *dev,
+ struct pci_saved_state **state)
+{
+ int ret = pci_load_saved_state(dev, *state);
+ kfree(*state);
+ *state = NULL;
+ return ret;
+}
+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 4dcb429..5457d99 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -812,6 +812,10 @@ 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);
+struct pci_saved_state *pci_store_saved_state(struct pci_dev *dev);
+int pci_load_saved_state(struct pci_dev *dev, struct pci_saved_state *state);
+int pci_load_and_free_saved_state(struct pci_dev *dev,
+ struct pci_saved_state **state);
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);
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