[PATCH 01/11] arch: arm64: Export arch_smp_send_reschedule for mshv_vtl module

[Naman Jain <namjain@linux.microsoft.com>]

mshv_vtl_main.c calls smp_send_reschedule() which expands to
arch_smp_send_reschedule(). When CONFIG_MSHV_VTL=m, the module cannot
access this symbol since it is not exported on arm64.

smp_send_reschedule() is used in mshv_vtl_cancel() to interrupt a vCPU
thread running on another CPU. When a vCPU is looping in
mshv_vtl_ioctl_return_to_lower_vtl(), it checks a per-CPU cancel flag
before each VTL0 entry. Setting cancel=1 alone is not enough if the
target CPU thread is sleeping - the IPI from smp_send_reschedule() kicks
the remote CPU out of idle/sleep so it re-checks the cancel flag and
exits the loop promptly.

Other architectures (riscv, loongarch, powerpc) already export this
symbol. Add the same EXPORT_SYMBOL_GPL for arm64. This is required
for adding arm64 support in MSHV_VTL.

Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
---
 arch/arm64/kernel/smp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 1aa324104afb..26b1a4456ceb 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -1152,6 +1152,7 @@ void arch_smp_send_reschedule(int cpu)
 {
 	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 }
+EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
 
 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
 void arch_send_wakeup_ipi(unsigned int cpu)
-- 
2.43.0