On Fri, Mar 11, 2016 at 08:34:58AM +1100, Benjamin Herrenschmidt wrote:
>On Thu, 2016-03-10 at 15:11 -0300, Guilherme G. Piccoli wrote:
>> The domain/PHB field of PCI addresses has its value obtained from a
>> global variable, incremented each time a new domain (represented by
>> struct pci_controller) is added on the system. The domain addition
>> process happens during boot or due to PCI device hotplug.
>
>I'd rather we use a fixed numbering for domains, for example, under
>OPAL, use the opal-id, under phyp, there is also a number in the DT we
>can use (forgot what it's called) etc...
>
guest on phyp has something like below:
ibm,fw-phb-id = <0x8000000 0x20000200>;
However, PowerKVM guest doesn't have it. I guess it's a problem, right?
Thanks,
Gavin
>> As recent kernels are using predictable naming for network
>> interfaces,
>> the network stack is more tied to PCI naming. This can be a problem
>> in
>> hotplug scenarios, because PCI addresses will change if a device is
>> removed and then re-added. This situation seems unusual, but it can
>> happen if a user wants to replace a NIC without rebooting the
>> machine,
>> for example.
>>
>> This patch changes the way PCI domain values are generated: the
>> global
>> variable is no longer used; instead, a list is introduced, containing
>> a flag that indicates whenever a domain is in use or was released,
>> for
>> example by a PCI hotplug remove. If the new PHB being added finds a
>> free domain, it will use its number; otherwise a new number is
>> generated incrementing the higher domain value present on the system.
>> No functional changes were introduced.
>>
>> Signed-off-by: Guilherme G. Piccoli <gpicc...@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/kernel/pci-common.c | 47
>> +++++++++++++++++++++++++++++++++++++---
>> 1 file changed, 44 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/pci-common.c
>> b/arch/powerpc/kernel/pci-common.c
>> index 0f7a60f..6eac0dd 100644
>> --- a/arch/powerpc/kernel/pci-common.c
>> +++ b/arch/powerpc/kernel/pci-common.c
>> @@ -44,8 +44,12 @@
>> static DEFINE_SPINLOCK(hose_spinlock);
>> LIST_HEAD(hose_list);
>>
>> -/* XXX kill that some day ... */
>> -static int global_phb_number; /* Global phb counter
>> */
>> +/* Global PHB counter list */
>> +struct global_phb_number {
>> + bool used;
>> + struct list_head node;
>> +};
>> +LIST_HEAD(global_phb_number_list);
>>
>> /* ISA Memory physical address */
>> resource_size_t isa_mem_base;
>> @@ -64,6 +68,42 @@ struct dma_map_ops *get_pci_dma_ops(void)
>> }
>> EXPORT_SYMBOL(get_pci_dma_ops);
>>
>> +static int get_phb_number(void)
>> +{
>> + struct global_phb_number *ptr;
>> + int latest_number = 0;
>> +
>> + list_for_each_entry(ptr, &global_phb_number_list, node) {
>> + if (!ptr->used) {
>> + ptr->used = true;
>> + return latest_number;
>> + }
>> + latest_number++;
>> + }
>> +
>> + ptr = zalloc_maybe_bootmem(sizeof(struct global_phb_number),
>> GFP_KERNEL);
>> + BUG_ON(ptr == NULL);
>> +
>> + ptr->used = true;
>> + list_add_tail(&ptr->node, &global_phb_number_list);
>> +
>> + return latest_number;
>> +}
>> +
>> +static void release_phb_number(int phb_number)
>> +{
>> + struct global_phb_number *ptr;
>> + int current_number = 0;
>> +
>> + list_for_each_entry(ptr, &global_phb_number_list, node) {
>> + if (current_number == phb_number) {
>> + ptr->used = false;
>> + return;
>> + }
>> + current_number++;
>> + }
>> +}
>> +
>> struct pci_controller *pcibios_alloc_controller(struct device_node
>> *dev)
>> {
>> struct pci_controller *phb;
>> @@ -72,7 +112,7 @@ struct pci_controller
>> *pcibios_alloc_controller(struct device_node *dev)
>> if (phb == NULL)
>> return NULL;
>> spin_lock(&hose_spinlock);
>> - phb->global_number = global_phb_number++;
>> + phb->global_number = get_phb_number();
>> list_add_tail(&phb->list_node, &hose_list);
>> spin_unlock(&hose_spinlock);
>> phb->dn = dev;
>> @@ -94,6 +134,7 @@ EXPORT_SYMBOL_GPL(pcibios_alloc_controller);
>> void pcibios_free_controller(struct pci_controller *phb)
>> {
>> spin_lock(&hose_spinlock);
>> + release_phb_number(phb->global_number);
>> list_del(&phb->list_node);
>> spin_unlock(&hose_spinlock);
>>
>
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