Re: [PATCH v4 27/28] PCI, x86, ACPI: Enable ioapic hotplug supportwith acpi host bridge.

[rui wang]

On 8/11/13, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> We need to have ioapic setup before normal pci drivers.
> otherwise other pci driver can not setup irq.
>
> So we should not treat them as normal pci devices.
> Also we will need to support ioapic hotplug without pci device around.
>
> We need to call ioapic add/remove during host-bridge add/remove.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> ---
>  drivers/acpi/pci_root.c  |   4 ++
>  drivers/pci/ioapic.c     | 147
> ++++++++++++++++++++++++++++++-----------------
>  include/linux/pci-acpi.h |   8 +++
>  3 files changed, 106 insertions(+), 53 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 5917839..7577175 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -532,6 +532,8 @@ static int acpi_pci_root_add(struct acpi_device
> *device,
>  		pci_enable_bridges(root->bus);
>  	}
>
> +	acpi_pci_ioapic_add(root);
> +
>  	pci_bus_add_devices(root->bus);
>  	return 1;
>
> @@ -546,6 +548,8 @@ static void acpi_pci_root_remove(struct acpi_device
> *device)
>
>  	pci_stop_root_bus(root->bus);
>
> +	acpi_pci_ioapic_remove(root);
> +
>  	device_set_run_wake(root->bus->bridge, false);
>  	pci_acpi_remove_bus_pm_notifier(device);
>
> diff --git a/drivers/pci/ioapic.c b/drivers/pci/ioapic.c
> index 7d6b157..60351b2 100644
> --- a/drivers/pci/ioapic.c
> +++ b/drivers/pci/ioapic.c
> @@ -22,101 +22,142 @@
>  #include <linux/slab.h>
>  #include <acpi/acpi_bus.h>
>
> -struct ioapic {
> -	acpi_handle	handle;
> +struct acpi_pci_ioapic {
> +	acpi_handle	root_handle;
>  	u32		gsi_base;
> +	struct pci_dev *pdev;
> +	struct list_head list;
>  };
>
> -static int ioapic_probe(struct pci_dev *dev, const struct pci_device_id
> *ent)
> +static LIST_HEAD(ioapic_list);
> +static DEFINE_MUTEX(ioapic_list_lock);
> +
> +static void handle_ioapic_add(acpi_handle handle, struct pci_dev **pdev,
> +				 u32 *pgsi_base)
>  {
> -	acpi_handle handle;
>  	acpi_status status;
>  	unsigned long long gsb;
> -	struct ioapic *ioapic;
> +	struct pci_dev *dev;
> +	u32 gsi_base;
>  	int ret;
>  	char *type;
> -	struct resource *res;
> +	struct resource r;
> +	struct resource *res = &r;
> +	char objname[64];
> +	struct acpi_buffer buffer = {sizeof(objname), objname};
>
> -	handle = DEVICE_ACPI_HANDLE(&dev->dev);
> -	if (!handle)
> -		return -EINVAL;
> +	*pdev = NULL;
> +	*pgsi_base = 0;
>
>  	status = acpi_evaluate_integer(handle, "_GSB", NULL, &gsb);
> -	if (ACPI_FAILURE(status))
> -		return -EINVAL;
> -
> -	/*
> -	 * The previous code in acpiphp evaluated _MAT if _GSB failed, but
> -	 * ACPI spec 4.0 sec 6.2.2 requires _GSB for hot-pluggable I/O APICs.
> -	 */
> +	if (ACPI_FAILURE(status) || !gsb)
> +		return;
>
> -	ioapic = kzalloc(sizeof(*ioapic), GFP_KERNEL);
> -	if (!ioapic)
> -		return -ENOMEM;
> +	dev = acpi_get_pci_dev(handle);
> +	if (!dev)
> +		return;
>
> -	ioapic->handle = handle;
> -	ioapic->gsi_base = (u32) gsb;
> +	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
>
> -	if (dev->class == PCI_CLASS_SYSTEM_PIC_IOAPIC)
> -		type = "IOAPIC";
> -	else
> -		type = "IOxAPIC";
> +	gsi_base = gsb;
> +	type = "IOxAPIC";
>
>  	ret = pci_enable_device(dev);
>  	if (ret < 0)
> -		goto exit_free;
> +		goto exit_put;
>
>  	pci_set_master(dev);
>
> +	if (dev->class == PCI_CLASS_SYSTEM_PIC_IOAPIC)
> +		type = "IOAPIC";
> +
>  	if (pci_request_region(dev, 0, type))
>  		goto exit_disable;
>
>  	res = &dev->resource[0];
> -	if (acpi_register_ioapic(ioapic->handle, res->start, ioapic->gsi_base))
> +
> +	if (acpi_register_ioapic(handle, res->start, gsi_base))
>  		goto exit_release;

Here acpi_register_ioapic() fails for IOAPICs already described by the
static MADT. So they won't be added to the ioapic_list. Subsequent
hot-removal will also fail because they're not found by
acpi_pci_ioapic_remove() on the ioapic_list.

Here's what I used to fix it: