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s390/pci: Allow allocation of more than 1 MSI interrupt

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On a PCI adapter that provides up to 8 MSI interrupt sources the s390
implementation of PCI interrupts rejected to accommodate them, although
the underlying hardware is able to support that.

For MSI-X it is sufficient to allocate a single irq_desc per msi_desc,
but for MSI multiple irq descriptors are attached to and controlled by
a single msi descriptor. Add the appropriate loops to maintain multiple
irq descriptors and tie/untie them to/from the appropriate AIBV bit, if
a device driver allocates more than 1 MSI interrupt.

Common PCI code passes on requests to allocate a number of interrupt
vectors based on the device drivers' demand and the PCI functions'
capabilities. However, the root-complex of s390 systems support just a
limited number of interrupt vectors per PCI function.
Produce a kernel log message to inform about any architecture-specific
capping that might be done.

With this change, we had a PCI adapter successfully raising
interrupts to its device driver via all 8 sources.

Fixes: a384c8924a ("s390/PCI: Fix single MSI only check")
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Gerd Bayer 2024-07-11 15:45:27 +02:00 committed by Vasily Gorbik
parent 5fd11b96b4
commit ab42fcb511
1 changed files with 42 additions and 20 deletions
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62
arch/s390/pci/pci_irq.c
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@ -298,8 +298,8 @@ static int __alloc_airq(struct zpci_dev *zdev, int msi_vecs,
int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
{
unsigned int hwirq, msi_vecs, irqs_per_msi, i, cpu;
struct zpci_dev *zdev = to_zpci(pdev);
unsigned int hwirq, msi_vecs, cpu;
struct msi_desc *msi;
struct msi_msg msg;
unsigned long bit;
@ -309,30 +309,46 @@ int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
zdev->aisb = -1UL;
zdev->msi_first_bit = -1U;
if (type == PCI_CAP_ID_MSI && nvec > 1)
return 1;
msi_vecs = min_t(unsigned int, nvec, zdev->max_msi);
if (msi_vecs < nvec) {
pr_info("%s requested %d irqs, allocate system limit of %d",
pci_name(pdev), nvec, zdev->max_msi);
}
rc = __alloc_airq(zdev, msi_vecs, &bit);
if (rc < 0)
return rc;
/* Request MSI interrupts */
/*
* Request MSI interrupts:
* When using MSI, nvec_used interrupt sources and their irq
* descriptors are controlled through one msi descriptor.
* Thus the outer loop over msi descriptors shall run only once,
* while two inner loops iterate over the interrupt vectors.
* When using MSI-X, each interrupt vector/irq descriptor
* is bound to exactly one msi descriptor (nvec_used is one).
* So the inner loops are executed once, while the outer iterates
* over the MSI-X descriptors.
*/
hwirq = bit;
msi_for_each_desc(msi, &pdev->dev, MSI_DESC_NOTASSOCIATED) {
rc = -EIO;
if (hwirq - bit >= msi_vecs)
break;
irq = __irq_alloc_descs(-1, 0, 1, 0, THIS_MODULE,
(irq_delivery == DIRECTED) ?
msi->affinity : NULL);
irqs_per_msi = min_t(unsigned int, msi_vecs, msi->nvec_used);
irq = __irq_alloc_descs(-1, 0, irqs_per_msi, 0, THIS_MODULE,
(irq_delivery == DIRECTED) ?
msi->affinity : NULL);
if (irq < 0)
return -ENOMEM;
rc = irq_set_msi_desc(irq, msi);
if (rc)
return rc;
irq_set_chip_and_handler(irq, &zpci_irq_chip,
handle_percpu_irq);
for (i = 0; i < irqs_per_msi; i++) {
rc = irq_set_msi_desc_off(irq, i, msi);
if (rc)
return rc;
irq_set_chip_and_handler(irq + i, &zpci_irq_chip,
handle_percpu_irq);
}
msg.data = hwirq - bit;
if (irq_delivery == DIRECTED) {
if (msi->affinity)
@ -345,31 +361,35 @@ int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
msg.address_lo |= (cpu_addr << 8);
for_each_possible_cpu(cpu) {
airq_iv_set_data(zpci_ibv[cpu], hwirq, irq);
for (i = 0; i < irqs_per_msi; i++)
airq_iv_set_data(zpci_ibv[cpu],
hwirq + i, irq + i);
}
} else {
msg.address_lo = zdev->msi_addr & 0xffffffff;
airq_iv_set_data(zdev->aibv, hwirq, irq);
for (i = 0; i < irqs_per_msi; i++)
airq_iv_set_data(zdev->aibv, hwirq + i, irq + i);
}
msg.address_hi = zdev->msi_addr >> 32;
pci_write_msi_msg(irq, &msg);
hwirq++;
hwirq += irqs_per_msi;
}
zdev->msi_first_bit = bit;
zdev->msi_nr_irqs = msi_vecs;
zdev->msi_nr_irqs = hwirq - bit;
rc = zpci_set_irq(zdev);
if (rc)
return rc;
return (msi_vecs == nvec) ? 0 : msi_vecs;
return (zdev->msi_nr_irqs == nvec) ? 0 : zdev->msi_nr_irqs;
}
void arch_teardown_msi_irqs(struct pci_dev *pdev)
{
struct zpci_dev *zdev = to_zpci(pdev);
struct msi_desc *msi;
unsigned int i;
int rc;
/* Disable interrupts */
@ -379,8 +399,10 @@ void arch_teardown_msi_irqs(struct pci_dev *pdev)
/* Release MSI interrupts */
msi_for_each_desc(msi, &pdev->dev, MSI_DESC_ASSOCIATED) {
irq_set_msi_desc(msi->irq, NULL);
irq_free_desc(msi->irq);
for (i = 0; i < msi->nvec_used; i++) {
irq_set_msi_desc(msi->irq + i, NULL);
irq_free_desc(msi->irq + i);
}
msi->msg.address_lo = 0;
msi->msg.address_hi = 0;
msi->msg.data = 0;