[patch V2 34/46] PCI/MSI: Make arch_.*_msi_irq[s] fallbacks selectable

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

The arch_.*_msi_irq[s] fallbacks are compiled in whether an architecture
requires them or not. Architectures which are fully utilizing hierarchical
irq domains should never call into that code.

It's not only architectures which depend on that by implementing one or
more of the weak functions, there is also a bunch of drivers which relies
on the weak functions which invoke msi_controller::setup_irq[s] and
msi_controller::teardown_irq.

Make the architectures and drivers which rely on them select them in Kconfig
and if not selected replace them by stub functions which emit a warning and
fail the PCI/MSI interrupt allocation.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
V2: Make the architectures (and drivers) which need the fallbacks select them
    and not the other way round (Bjorn).
---
 arch/ia64/Kconfig              |    1 +
 arch/mips/Kconfig              |    1 +
 arch/powerpc/Kconfig           |    1 +
 arch/s390/Kconfig              |    1 +
 arch/sparc/Kconfig             |    1 +
 arch/x86/Kconfig               |    1 +
 drivers/pci/Kconfig            |    3 +++
 drivers/pci/controller/Kconfig |    3 +++
 drivers/pci/msi.c              |    3 ++-
 include/linux/msi.h            |   31 ++++++++++++++++++++++++++-----
 10 files changed, 40 insertions(+), 6 deletions(-)

--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -56,6 +56,7 @@ config IA64
        select NEED_DMA_MAP_STATE
        select NEED_SG_DMA_LENGTH
        select NUMA if !FLATMEM
+       select PCI_MSI_ARCH_FALLBACKS
        default y
        help
          The Itanium Processor Family is Intel's 64-bit successor to
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -86,6 +86,7 @@ config MIPS
        select MODULES_USE_ELF_REL if MODULES
        select MODULES_USE_ELF_RELA if MODULES && 64BIT
        select PERF_USE_VMALLOC
+       select PCI_MSI_ARCH_FALLBACKS
        select RTC_LIB
        select SYSCTL_EXCEPTION_TRACE
        select VIRT_TO_BUS
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -246,6 +246,7 @@ config PPC
        select OLD_SIGACTION                    if PPC32
        select OLD_SIGSUSPEND
        select PCI_DOMAINS                      if PCI
+       select PCI_MSI_ARCH_FALLBACKS
        select PCI_SYSCALL                      if PCI
        select PPC_DAWR                         if PPC64
        select RTC_LIB
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -185,6 +185,7 @@ config S390
        select OLD_SIGSUSPEND3
        select PCI_DOMAINS              if PCI
        select PCI_MSI                  if PCI
+       select PCI_MSI_ARCH_FALLBACKS
        select SPARSE_IRQ
        select SYSCTL_EXCEPTION_TRACE
        select THREAD_INFO_IN_TASK
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -43,6 +43,7 @@ config SPARC
        select GENERIC_STRNLEN_USER
        select MODULES_USE_ELF_RELA
        select PCI_SYSCALL if PCI
+       select PCI_MSI_ARCH_FALLBACKS
        select ODD_RT_SIGACTION
        select OLD_SIGSUSPEND
        select CPU_NO_EFFICIENT_FFS
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -225,6 +225,7 @@ 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
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -56,6 +56,9 @@ config PCI_MSI_IRQ_DOMAIN
        depends on PCI_MSI
        select GENERIC_MSI_IRQ_DOMAIN
 
+config PCI_MSI_ARCH_FALLBACKS
+       bool
+
 config PCI_QUIRKS
        default y
        bool "Enable PCI quirk workarounds" if EXPERT
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -41,6 +41,7 @@ config PCI_TEGRA
        bool "NVIDIA Tegra PCIe controller"
        depends on ARCH_TEGRA || COMPILE_TEST
        depends on PCI_MSI_IRQ_DOMAIN
+       select PCI_MSI_ARCH_FALLBACKS
        help
          Say Y here if you want support for the PCIe host controller found
          on NVIDIA Tegra SoCs.
@@ -67,6 +68,7 @@ config PCIE_RCAR_HOST
        bool "Renesas R-Car PCIe host controller"
        depends on ARCH_RENESAS || COMPILE_TEST
        depends on PCI_MSI_IRQ_DOMAIN
+       select PCI_MSI_ARCH_FALLBACKS
        help
          Say Y here if you want PCIe controller support on R-Car SoCs in host
          mode.
@@ -103,6 +105,7 @@ config PCIE_XILINX_CPM
        bool "Xilinx Versal CPM host bridge support"
        depends on ARCH_ZYNQMP || COMPILE_TEST
        select PCI_HOST_COMMON
+       select PCI_MSI_ARCH_FALLBACKS
        help
          Say 'Y' here if you want kernel support for the
          Xilinx Versal CPM host bridge.
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -58,8 +58,8 @@ static void pci_msi_teardown_msi_irqs(st
 #define pci_msi_teardown_msi_irqs      arch_teardown_msi_irqs
 #endif
 
+#ifdef CONFIG_PCI_MSI_ARCH_FALLBACKS
 /* Arch hooks */
-
 int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 {
        struct msi_controller *chip = dev->bus->msi;
@@ -132,6 +132,7 @@ void __weak arch_teardown_msi_irqs(struc
 {
        return default_teardown_msi_irqs(dev);
 }
+#endif /* CONFIG_PCI_MSI_ARCH_FALLBACKS */
 
 static void default_restore_msi_irq(struct pci_dev *dev, int irq)
 {
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -193,17 +193,38 @@ void pci_msi_mask_irq(struct irq_data *d
 void pci_msi_unmask_irq(struct irq_data *data);
 
 /*
- * The arch hooks to setup up msi irqs. Those functions are
- * implemented as weak symbols so that they /can/ be overriden by
- * architecture specific code if needed.
+ * The arch hooks to setup up msi irqs. Default functions are implemented
+ * as weak symbols so that they /can/ be overriden by architecture specific
+ * code if needed. These hooks must be enabled by the architecture or by
+ * drivers which depend on them via msi_controller based MSI handling.
+ *
+ * If CONFIG_PCI_MSI_ARCH_FALLBACKS is not selected they are replaced by
+ * stubs with warnings.
  */
+#ifdef CONFIG_PCI_MSI_DISABLE_ARCH_FALLBACKS
 int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc);
 void arch_teardown_msi_irq(unsigned int irq);
 int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type);
 void arch_teardown_msi_irqs(struct pci_dev *dev);
-void arch_restore_msi_irqs(struct pci_dev *dev);
-
 void default_teardown_msi_irqs(struct pci_dev *dev);
+#else
+static inline int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
+{
+       WARN_ON_ONCE(1);
+       return -ENODEV;
+}
+
+static inline void arch_teardown_msi_irqs(struct pci_dev *dev)
+{
+       WARN_ON_ONCE(1);
+}
+#endif
+
+/*
+ * The restore hooks are still available as they are useful even
+ * for fully irq domain based setups. Courtesy to XEN/X86.
+ */
+void arch_restore_msi_irqs(struct pci_dev *dev);
 void default_restore_msi_irqs(struct pci_dev *dev);
 
 struct msi_controller {