Consolidate the machine_kexec_mask_interrupts implementation into a common
function located in a new file: kernel/irq/kexec.c. This removes duplicate
implementations from architecture-specific files in arch/arm, arch/arm64,
arch/powerpc, and arch/riscv, reducing code duplication and improving
maintainability.

The new implementation retains architecture-specific behavior for
CONFIG_GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD, which was previously implemented
for ARM64. When enabled (currently for ARM64), it clears the active state
of interrupts forwarded to virtual machines (VMs) before handling other
interrupt masking operations.

Signed-off-by: Eliav Farber <redacted>
---
V5 -> V6:
 - Change GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD to not be user selectable.

 arch/arm/kernel/machine_kexec.c   | 23 ------------------
 arch/arm64/Kconfig                |  1 +
 arch/arm64/kernel/machine_kexec.c | 31 ------------------------
 arch/powerpc/include/asm/kexec.h  |  1 -
 arch/powerpc/kexec/core.c         | 22 -----------------
 arch/powerpc/kexec/core_32.c      |  1 +
 arch/riscv/kernel/machine_kexec.c | 23 ------------------
 include/linux/irq.h               |  3 +++
 kernel/irq/Kconfig                |  6 +++++
 kernel/irq/Makefile               |  2 +-
 kernel/irq/kexec.c                | 40 +++++++++++++++++++++++++++++++
 11 files changed, 52 insertions(+), 101 deletions(-)
 create mode 100644 kernel/irq/kexec.c

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 80ceb5bd2680..dd430477e7c1 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c

@@ -127,29 +127,6 @@ void crash_smp_send_stop(void)
 	cpus_stopped = 1;
 }
 
-static void machine_kexec_mask_interrupts(void)
-{
-	unsigned int i;
-	struct irq_desc *desc;
-
-	for_each_irq_desc(i, desc) {
-		struct irq_chip *chip;
-
-		chip = irq_desc_get_chip(desc);
-		if (!chip)
-			continue;
-
-		if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
-			chip->irq_eoi(&desc->irq_data);
-
-		if (chip->irq_mask)
-			chip->irq_mask(&desc->irq_data);
-
-		if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
-			chip->irq_disable(&desc->irq_data);
-	}
-}
-
 void machine_crash_shutdown(struct pt_regs *regs)
 {
 	local_irq_disable();

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 100570a048c5..dcc3551cf6c2 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -149,6 +149,7 @@ config ARM64
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_IOREMAP
 	select GENERIC_IRQ_IPI
+	select GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD

diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 82e2203d86a3..6f121a0164a4 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c

@@ -207,37 +207,6 @@ void machine_kexec(struct kimage *kimage)
 	BUG(); /* Should never get here. */
 }
 
-static void machine_kexec_mask_interrupts(void)
-{
-	unsigned int i;
-	struct irq_desc *desc;
-
-	for_each_irq_desc(i, desc) {
-		struct irq_chip *chip;
-		int ret;
-
-		chip = irq_desc_get_chip(desc);
-		if (!chip)
-			continue;
-
-		/*
-		 * First try to remove the active state. If this
-		 * fails, try to EOI the interrupt.
-		 */
-		ret = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false);