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SubjectRe: [PATCH v5 3/6] PCI: add functionality for resizing resources v6
On Fri, Jun 09, 2017 at 10:59:44AM +0200, Christian König wrote:
> From: Christian König <christian.koenig@amd.com>
>
> This allows device drivers to request resizing their BARs.
>
> The function only tries to reprogram the windows of the bridge directly above
> the requesting device and only the BAR of the same type (usually mem, 64bit,
> prefetchable). This is done to make sure not to disturb other drivers by
> changing the BARs of their devices.
>
> If reprogramming the bridge BAR fails the old status is restored and -ENOSPC
> returned to the calling device driver.

Can you include an outline of how drivers should use
pci_resize_resource() here, including disabling decoding, releasing
resource(s), resizing, re-enabling decoding, re-reading
pdev->resource[]?

> v2: rebase on changes in rbar support
> v3: style cleanups, fail if memory decoding is enabled or resources
> still allocated, resize all unused bridge BARs,
> drop calling pci_reenable_device
> v4: print resources before releasing them, style cleanups,
> use pci_rbar_size_to_bytes, use PCI_RES_TYPE_MASK
> v5: use next pointer to simplify loop
> v6: move reassigning resources on error to driver side
>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
> drivers/pci/setup-bus.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/pci/setup-res.c | 58 +++++++++++++++++++++++++++++
> include/linux/pci.h | 3 ++
> 3 files changed, 159 insertions(+)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 451a9c0..2ea872d 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1908,6 +1908,104 @@ void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
> }
> EXPORT_SYMBOL_GPL(pci_assign_unassigned_bridge_resources);
>
> +int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type)
> +{
> + struct pci_dev_resource *dev_res;
> + struct pci_dev *next;
> + LIST_HEAD(saved);
> + LIST_HEAD(added);
> + LIST_HEAD(failed);
> + unsigned int i;
> + int ret;
> +
> + /* Walk to the root hub, releasing bridge BARs when possible */
> + next = bridge;
> + do {
> + bridge = next;
> + for (i = PCI_BRIDGE_RESOURCES; i < PCI_BRIDGE_RESOURCE_END;
> + i++) {
> + struct resource *res = &bridge->resource[i];
> +
> + if ((res->flags ^ type) & PCI_RES_TYPE_MASK)
> + continue;
> +
> + /* Ignore BARs which are still in use */
> + if (res->child)
> + continue;
> +
> + ret = add_to_list(&saved, bridge, res, 0, 0);
> + if (ret)
> + goto cleanup;
> +
> + dev_info(&bridge->dev, "BAR %d: releasing %pR\n",
> + i, res);
> +
> + if (res->parent)
> + release_resource(res);
> + res->start = 0;
> + res->end = 0;
> + break;
> + }
> + if (i == PCI_BRIDGE_RESOURCE_END)
> + break;
> +
> + next = bridge->bus ? bridge->bus->self : NULL;
> + } while (next);
> +
> + if (list_empty(&saved))
> + return -ENOENT;
> +
> + __pci_bus_size_bridges(bridge->subordinate, &added);
> + __pci_bridge_assign_resources(bridge, &added, &failed);
> + BUG_ON(!list_empty(&added));
> +
> + if (!list_empty(&failed)) {
> + ret = -ENOSPC;
> + goto cleanup;
> + }
> +
> + list_for_each_entry(dev_res, &saved, list) {
> + /* Skip the bridge we just assigned resources for. */
> + if (bridge == dev_res->dev)
> + continue;
> +
> + bridge = dev_res->dev;
> + pci_setup_bridge(bridge->subordinate);
> + }
> +
> + free_list(&saved);
> + return 0;
> +
> +cleanup:
> + /* restore size and flags */
> + list_for_each_entry(dev_res, &failed, list) {
> + struct resource *res = dev_res->res;
> +
> + res->start = dev_res->start;
> + res->end = dev_res->end;
> + res->flags = dev_res->flags;
> + }
> + free_list(&failed);
> +
> + /* Revert to the old configuration */
> + list_for_each_entry(dev_res, &saved, list) {
> + struct resource *res = dev_res->res;
> +
> + bridge = dev_res->dev;
> + i = res - bridge->resource;
> +
> + res->start = dev_res->start;
> + res->end = dev_res->end;
> + res->flags = dev_res->flags;
> +
> + pci_claim_resource(bridge, i);
> + pci_setup_bridge(bridge->subordinate);
> + }
> + free_list(&saved);
> +
> + return ret;
> +}
> +
> void pci_assign_unassigned_bus_resources(struct pci_bus *bus)
> {
> struct pci_dev *dev;
> diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
> index 4bc589e..077c515 100644
> --- a/drivers/pci/setup-res.c
> +++ b/drivers/pci/setup-res.c
> @@ -383,6 +383,64 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
> return 0;
> }
>
> +void pci_release_resource(struct pci_dev *dev, int resno)
> +{
> + struct resource *res = dev->resource + resno;
> +
> + dev_info(&dev->dev, "BAR %d: releasing %pR\n", resno, res);
> + release_resource(res);
> + res->end = resource_size(res) - 1;
> + res->start = 0;
> + res->flags |= IORESOURCE_UNSET;
> +}
> +EXPORT_SYMBOL(pci_release_resource);
> +
> +int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> +{
> + struct resource *res = dev->resource + resno;
> + int old, ret;
> + u32 sizes;
> + u16 cmd;
> +
> + /* Make sure the resource isn't assigned before resizing it. */
> + if (!(res->flags & IORESOURCE_UNSET))
> + return -EBUSY;
> +
> + pci_read_config_word(dev, PCI_COMMAND, &cmd);
> + if (cmd & PCI_COMMAND_MEMORY)
> + return -EBUSY;
> +
> + sizes = pci_rbar_get_possible_sizes(dev, resno);
> + if (!sizes)
> + return -ENOTSUPP;
> +
> + if (!(sizes & BIT(size)))
> + return -EINVAL;
> +
> + old = pci_rbar_get_current_size(dev, resno);
> + if (old < 0)
> + return old;
> +
> + ret = pci_rbar_set_size(dev, resno, size);
> + if (ret)
> + return ret;
> +
> + res->end = res->start + pci_rbar_size_to_bytes(size) - 1;
> +
> + /* Check if the new config works by trying to assign everything. */
> + ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
> + if (ret)
> + goto error_resize;
> +
> + return 0;
> +
> +error_resize:
> + pci_rbar_set_size(dev, resno, old);
> + res->end = res->start + pci_rbar_size_to_bytes(old) - 1;
> + return ret;
> +}
> +EXPORT_SYMBOL(pci_resize_resource);
> +
> int pci_enable_resources(struct pci_dev *dev, int mask)
> {
> u16 cmd, old_cmd;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index eb3da1a..2d631ad 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1068,6 +1068,8 @@ void pci_reset_bridge_secondary_bus(struct pci_dev *dev);
> void pci_update_resource(struct pci_dev *dev, int resno);
> int __must_check pci_assign_resource(struct pci_dev *dev, int i);
> int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);
> +void pci_release_resource(struct pci_dev *dev, int resno);
> +int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size);
> int pci_select_bars(struct pci_dev *dev, unsigned long flags);
> bool pci_device_is_present(struct pci_dev *pdev);
> void pci_ignore_hotplug(struct pci_dev *dev);
> @@ -1148,6 +1150,7 @@ void pci_assign_unassigned_resources(void);
> void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge);
> void pci_assign_unassigned_bus_resources(struct pci_bus *bus);
> void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus);
> +int pci_reassign_bridge_resources(struct pci_dev *bridge, unsigned long type);
> void pdev_enable_device(struct pci_dev *);
> int pci_enable_resources(struct pci_dev *, int mask);
> void pci_fixup_irqs(u8 (*)(struct pci_dev *, u8 *),
> --
> 2.7.4
>

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