x86/irq: Cleanup the arch_*_msi_irqs() leftovers

Get rid of all the gunk and remove the 'select PCI_MSI_ARCH_FALLBACK' from
the x86 Kconfig so the weak functions in the PCI core are replaced by stubs
which emit a warning, which ensures that any fail to set the irq domain
pointer results in a warning when the device is used.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112334.086003720@linutronix.de

Author: KAGA-KOKO

arch/x86/Kconfig

@@ -225,7 +225,6 @@ config X86
 	select NEED_SG_DMA_LENGTH
 	select PCI_DOMAINS			if PCI
 	select PCI_LOCKLESS_CONFIG		if PCI
-	select PCI_MSI_ARCH_FALLBACKS
 	select PERF_EVENTS
 	select RTC_LIB
 	select RTC_MC146818_LIB

arch/x86/include/asm/pci.h

@@ -105,17 +105,6 @@ static inline void early_quirks(void) { }
 
 extern void pci_iommu_alloc(void);
 
-#ifdef CONFIG_PCI_MSI
-/* implemented in arch/x86/kernel/apic/io_apic. */
-struct msi_desc;
-int native_setup_msi_irqs(struct pci_dev *dev, int nvec, int type);
-void native_teardown_msi_irq(unsigned int irq);
-void native_restore_msi_irqs(struct pci_dev *dev);
-#else
-#define native_setup_msi_irqs		NULL
-#define native_teardown_msi_irq		NULL
-#endif
-
 /* generic pci stuff */
 #include <asm-generic/pci.h>
 

arch/x86/include/asm/x86_init.h

@@ -277,7 +277,6 @@ struct pci_dev;
 
 struct x86_msi_ops {
 	int (*setup_msi_irqs)(struct pci_dev *dev, int nvec, int type);
-	void (*teardown_msi_irq)(unsigned int irq);
 	void (*teardown_msi_irqs)(struct pci_dev *dev);
 	void (*restore_msi_irqs)(struct pci_dev *dev);
 };

arch/x86/kernel/apic/msi.c

@@ -181,28 +181,6 @@ static struct irq_chip pci_msi_controller = {
 	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };
 
-int native_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
-{
-	struct irq_domain *domain;
-	struct irq_alloc_info info;
-
-	init_irq_alloc_info(&info, NULL);
-	info.type = X86_IRQ_ALLOC_TYPE_PCI_MSI;
-
-	domain = irq_remapping_get_irq_domain(&info);
-	if (domain == NULL)
-		domain = x86_pci_msi_default_domain;
-	if (domain == NULL)
-		return -ENOSYS;
-
-	return msi_domain_alloc_irqs(domain, &dev->dev, nvec);
-}
-
-void native_teardown_msi_irq(unsigned int irq)
-{
-	irq_domain_free_irqs(irq, 1);
-}
-
 int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
 		    msi_alloc_info_t *arg)
 {

arch/x86/kernel/x86_init.c

@@ -146,28 +146,10 @@ EXPORT_SYMBOL_GPL(x86_platform);
 
 #if defined(CONFIG_PCI_MSI)
 struct x86_msi_ops x86_msi __ro_after_init = {
-	.setup_msi_irqs		= native_setup_msi_irqs,
-	.teardown_msi_irq	= native_teardown_msi_irq,
-	.teardown_msi_irqs	= default_teardown_msi_irqs,
 	.restore_msi_irqs	= default_restore_msi_irqs,
 };
 
 /* MSI arch specific hooks */
-int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
-{
-	return x86_msi.setup_msi_irqs(dev, nvec, type);
-}
-
-void arch_teardown_msi_irqs(struct pci_dev *dev)
-{
-	x86_msi.teardown_msi_irqs(dev);
-}
-
-void arch_teardown_msi_irq(unsigned int irq)
-{
-	x86_msi.teardown_msi_irq(irq);
-}
-
 void arch_restore_msi_irqs(struct pci_dev *dev)
 {
 	x86_msi.restore_msi_irqs(dev);

arch/x86/pci/xen.c

@@ -402,11 +402,6 @@ static void xen_pv_teardown_msi_irqs(struct pci_dev *dev)
 	xen_teardown_msi_irqs(dev);
 }
 
-static void xen_teardown_msi_irq(unsigned int irq)
-{
-	WARN_ON_ONCE(1);
-}
-
 static int xen_msi_domain_alloc_irqs(struct irq_domain *domain,
 				     struct device *dev,  int nvec)
 {
@@ -483,8 +478,6 @@ static __init void xen_setup_pci_msi(void)
 		return;
 	}
 
-	x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
-
 	/*
 	 * Override the PCI/MSI irq domain init function. No point
 	 * in allocating the native domain and never use it.