Re: [PATCH v2 2/2] powerpc/pci: unmap all interrupts when a PHB is removed

On 8/7/20 8:01 AM, Alexey Kardashevskiy wrote:

On 18/06/2020 02:29, Cédric Le Goater wrote:

quoted

Some PCI adapters, like GPUs, use the "interrupt-map" property to
describe interrupt mappings other than the legacy INTx interrupts.
There can be more than 4 mappings.

To clear all interrupts when a PHB is removed, we need to increase the
'irq_map' array in which mappings are recorded. Compute the number of
interrupt mappings from the "interrupt-map" property and allocate a
bigger 'irq_map' array.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 arch/powerpc/kernel/pci-common.c | 49 +++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 515480a4bac6..deb831f0ae13 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c

@@ -353,9 +353,56 @@ struct pci_controller *pci_find_controller_for_domain(int domain_nr)
 	return NULL;
 }
 
+/*
+ * Assumption is made on the interrupt parent. All interrupt-map
+ * entries are considered to have the same parent.
+ */
+static int pcibios_irq_map_count(struct pci_controller *phb)

I wonder if
int of_irq_count(struct device_node *dev)
could work here too. If it does not, then never mind.

I wished it would, but no.

Other than that, the only other comment is - merge this one into 1/2 as
1/2 alone won't properly fix the problem but it may look like that it does:

for phyp, the test machine just happens to have 4 entries in the map but
this is the phyp implementation detail;

yes
 

for qemu, there are more but we only unregister 4 but kvm does not care
in general so it is ok which is also implementation detail;

and 2/2 just makes these details not matter. Thanks,

OK. It will ease backport. Sending a v2.

Thanks for the review Alexey !

C.
 

quoted

+{
+	const __be32 *imap;
+	int imaplen;
+	struct device_node *parent;
+	u32 intsize, addrsize, parintsize, paraddrsize;
+
+	if (of_property_read_u32(phb->dn, "#interrupt-cells", &intsize))
+		return 0;
+	if (of_property_read_u32(phb->dn, "#address-cells", &addrsize))
+		return 0;
+
+	imap = of_get_property(phb->dn, "interrupt-map", &imaplen);
+	if (!imap) {
+		pr_debug("%pOF : no interrupt-map\n", phb->dn);
+		return 0;
+	}
+	imaplen /= sizeof(u32);
+	pr_debug("%pOF : imaplen=%d\n", phb->dn, imaplen);
+
+	if (imaplen < (addrsize + intsize + 1))
+		return 0;
+
+	imap += intsize + addrsize;
+	parent = of_find_node_by_phandle(be32_to_cpup(imap));
+	if (!parent) {
+		pr_debug("%pOF : no imap parent found !\n", phb->dn);
+		return 0;
+	}
+
+	if (of_property_read_u32(parent, "#interrupt-cells", &parintsize)) {
+		pr_debug("%pOF : parent lacks #interrupt-cells!\n", phb->dn);
+		return 0;
+	}
+
+	if (of_property_read_u32(parent, "#address-cells", &paraddrsize))
+		paraddrsize = 0;
+
+	return imaplen / (addrsize + intsize + 1 + paraddrsize + parintsize);
+}
+
 static void pcibios_irq_map_init(struct pci_controller *phb)
 {
-	phb->irq_count = PCI_NUM_INTX;
+	phb->irq_count = pcibios_irq_map_count(phb);
+	if (phb->irq_count < PCI_NUM_INTX)
+		phb->irq_count = PCI_NUM_INTX;
 
 	pr_debug("%pOF : interrupt map #%d\n", phb->dn, phb->irq_count);