[patch RFC 23/38] x86/xen: Rework MSI teardown

Thomas Gleixner
2020-08-21T02:18:55Z

[-- Attachment #1: x86-xen--Rework-XEN-MSI-management.patch --]
[-- Type: text/plain, Size: 2588 bytes --]

X86 cannot store the irq domain pointer in struct device without breaking
XEN because the irq domain pointer takes precedence over arch_*_msi_irqs()
fallbacks.

XENs MSI teardown relies on default_teardown_msi_irqs() which invokes
arch_teardown_msi_irq(). default_teardown_msi_irqs() is a trivial iterator
over the msi entries associated to a device.

Implement this loop in xen_teardown_msi_irqs() to prepare for removal of
the fallbacks for X86.

This is a preparatory step to wrap XEN MSI alloc/free into a irq domain
which in turn allows to store the irq domain pointer in struct device and
to use the irq domain functions directly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/pci/xen.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)

--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -376,20 +376,31 @@ static void xen_initdom_restore_msi_irqs
static void xen_teardown_msi_irqs(struct pci_dev *dev)
{
struct msi_desc *msidesc;
+ int i;
+
+ for_each_pci_msi_entry(msidesc, dev) {
+ if (msidesc->irq) {
+ for (i = 0; i < msidesc->nvec_used; i++)
+ xen_destroy_irq(msidesc->irq + i);
+ }
+ }
+}
+
+static void xen_pv_teardown_msi_irqs(struct pci_dev *dev)
+{
+ struct msi_desc *msidesc = first_pci_msi_entry(dev);

- msidesc = first_pci_msi_entry(dev);
if (msidesc->msi_attrib.is_msix)
xen_pci_frontend_disable_msix(dev);
else
xen_pci_frontend_disable_msi(dev);

- /* Free the IRQ's and the msidesc using the generic code. */
- default_teardown_msi_irqs(dev);
+ xen_teardown_msi_irqs(dev);
}

static void xen_teardown_msi_irq(unsigned int irq)
{
- xen_destroy_irq(irq);
+ WARN_ON_ONCE(1);
}

#endif
@@ -412,7 +423,7 @@ int __init pci_xen_init(void)
#ifdef CONFIG_PCI_MSI
x86_msi.setup_msi_irqs = xen_setup_msi_irqs;
x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
- x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
+ x86_msi.teardown_msi_irqs = xen_pv_teardown_msi_irqs;
pci_msi_ignore_mask = 1;
#endif
return 0;
@@ -436,6 +447,7 @@ static void __init xen_hvm_msi_init(void
}

x86_msi.setup_msi_irqs = xen_hvm_setup_msi_irqs;
+ x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
}
#endif
@@ -472,6 +484,7 @@ int __init pci_xen_initial_domain(void)
#ifdef CONFIG_PCI_MSI
x86_msi.setup_msi_irqs = xen_initdom_setup_msi_irqs;
x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
+ x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
x86_msi.restore_msi_irqs = xen_initdom_restore_msi_irqs;
pci_msi_ignore_mask = 1;
#endif