From: Dexuan Cui decui@microsoft.com
[ Upstream commit 711419e504ebd68c8f03656616829c8ad7829389 ]
Recently device pass-through stops working for Linux VM running on Hyper-V.
git-bisect shows the regression is caused by the recent commit 467a3bb97432 ("PCI: hv: Allocate a named fwnode ..."), but the root cause is that the commit d59f6617eef0 forgets to set the domain->fwnode for IRQCHIP_FWNODE_NAMED*, and as a result:
1. The domain->fwnode remains to be NULL.
2. irq_find_matching_fwspec() returns NULL since "h->fwnode == fwnode" is false, and pci_set_bus_msi_domain() sets the Hyper-V PCI root bus's msi_domain to NULL.
3. When the device is added onto the root bus, the device's dev->msi_domain is set to NULL in pci_set_msi_domain().
4. When a device driver tries to enable MSI-X, pci_msi_setup_msi_irqs() calls arch_setup_msi_irqs(), which uses the native MSI chip (i.e. arch/x86/kernel/apic/msi.c: pci_msi_controller) to set up the irqs, but actually pci_msi_setup_msi_irqs() is supposed to call msi_domain_alloc_irqs() with the hbus->irq_domain, which is created in hv_pcie_init_irq_domain() and is associated with the Hyper-V chip hv_msi_irq_chip. Consequently, the irq line is not properly set up, and the device driver can not receive any interrupt.
Fixes: d59f6617eef0 ("genirq: Allow fwnode to carry name information only") Fixes: 467a3bb97432 ("PCI: hv: Allocate a named fwnode instead of an address-based one") Reported-by: Lili Deng v-lide@microsoft.com Signed-off-by: Dexuan Cui decui@microsoft.com Signed-off-by: Marc Zyngier maz@kernel.org Link: https://lore.kernel.org/r/PU1P153MB01694D9AF625AC335C600C5FBFBE0@PU1P153MB01... Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/irq/irqdomain.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 0b90be3607249..6e8520a81dd86 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -148,6 +148,7 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size, switch (fwid->type) { case IRQCHIP_FWNODE_NAMED: case IRQCHIP_FWNODE_NAMED_ID: + domain->fwnode = fwnode; domain->name = kstrdup(fwid->name, GFP_KERNEL); if (!domain->name) { kfree(domain);