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

From: Thomas Gleixner
Date: Wed Aug 26 2020 - 08:09:55 EST

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 {