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PCI/portdrv: Do not setup up IRQs if there are no users

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Avoid registering service IRQs if there is no service that offers them
or no driver to register a handler against them. This saves IRQ vectors
when they are limited (e.g. on x86) and also avoids that spurious events
could hit a missing handler. Such spurious events need to be generated
by the Jailhouse hypervisor for active MSI vectors when enabling or
disabling itself.

Link: https://lore.kernel.org/r/8f9a13ac-8ab1-15ac-06cb-c131b488a36f@siemens.com
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Jan Kiszka 2021-08-30 10:08:10 +02:00 • committed by Bjorn Helgaas
parent e4e737bb5c
commit 0e8ae5a6ff
1 changed files with 30 additions and 17 deletions
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47
drivers/pci/pcie/portdrv_core.c
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@ -166,9 +166,6 @@ static int pcie_init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
{ {
int ret, i; int ret, i;
for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
irqs[i] = -1;
/* /*
* If we support PME but can't use MSI/MSI-X for it, we have to * If we support PME but can't use MSI/MSI-X for it, we have to
* fall back to INTx or other interrupts, e.g., a system shared * fall back to INTx or other interrupts, e.g., a system shared
@ -317,8 +314,10 @@ static int pcie_device_init(struct pci_dev *pdev, int service, int irq)
*/ */
int pcie_port_device_register(struct pci_dev *dev) int pcie_port_device_register(struct pci_dev *dev)
{ {
int status, capabilities, i, nr_service; int status, capabilities, irq_services, i, nr_service;
int irqs[PCIE_PORT_DEVICE_MAXSERVICES]; int irqs[PCIE_PORT_DEVICE_MAXSERVICES] = {
[0 ... PCIE_PORT_DEVICE_MAXSERVICES-1] = -1
};
/* Enable PCI Express port device */ /* Enable PCI Express port device */
status = pci_enable_device(dev); status = pci_enable_device(dev);
@ -331,18 +330,32 @@ int pcie_port_device_register(struct pci_dev *dev)
return 0; return 0;
pci_set_master(dev); pci_set_master(dev);
/*
* Initialize service irqs. Don't use service devices that irq_services = 0;
* require interrupts if there is no way to generate them. if (IS_ENABLED(CONFIG_PCIE_PME))
* However, some drivers may have a polling mode (e.g. pciehp_poll_mode) irq_services |= PCIE_PORT_SERVICE_PME;
* that can be used in the absence of irqs. Allow them to determine if (IS_ENABLED(CONFIG_PCIEAER))
* if that is to be used. irq_services |= PCIE_PORT_SERVICE_AER;
*/ if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
status = pcie_init_service_irqs(dev, irqs, capabilities); irq_services |= PCIE_PORT_SERVICE_HP;
if (status) { if (IS_ENABLED(CONFIG_PCIE_DPC))
capabilities &= PCIE_PORT_SERVICE_HP; irq_services |= PCIE_PORT_SERVICE_DPC;
if (!capabilities) irq_services &= capabilities;
goto error_disable;
if (irq_services) {
/*
* Initialize service IRQs. Don't use service devices that
* require interrupts if there is no way to generate them.
* However, some drivers may have a polling mode (e.g.
* pciehp_poll_mode) that can be used in the absence of IRQs.
* Allow them to determine if that is to be used.
*/
status = pcie_init_service_irqs(dev, irqs, irq_services);
if (status) {
irq_services &= PCIE_PORT_SERVICE_HP;
if (!irq_services)
goto error_disable;
}
} }
/* Allocate child services if any */ /* Allocate child services if any */