clocksource/arm_arch_timer: Store physical timer IRQ number for KVM on VHE

A host running in VHE mode gets the EL2 physical timer as its time
source (accessed using the EL1 sysreg accessors, which get re-directed
to the EL2 sysregs by VHE).

The EL1 physical timer remains unused by the host kernel, allowing us to
pass that on directly to a KVM guest and saves us from emulating this
timer for the guest on VHE systems.

Store the EL1 Physical Timer's IRQ number in
struct arch_timer_kvm_info on VHE systems to allow KVM to use it.
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@arm.com>

drivers/clocksource/arm_arch_timer.c

@@ -1206,6 +1206,13 @@ static enum arch_timer_ppi_nr __init arch_timer_select_ppi(void)
 	return ARCH_TIMER_PHYS_SECURE_PPI;
 }
 
+static void __init arch_timer_populate_kvm_info(void)
+{
+	arch_timer_kvm_info.virtual_irq = arch_timer_ppi[ARCH_TIMER_VIRT_PPI];
+	if (is_kernel_in_hyp_mode())
+		arch_timer_kvm_info.physical_irq = arch_timer_ppi[ARCH_TIMER_PHYS_NONSECURE_PPI];
+}
+
 static int __init arch_timer_of_init(struct device_node *np)
 {
 	int i, ret;
@@ -1220,7 +1227,7 @@ static int __init arch_timer_of_init(struct device_node *np)
 	for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++)
 		arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
 
-	arch_timer_kvm_info.virtual_irq = arch_timer_ppi[ARCH_TIMER_VIRT_PPI];
+	arch_timer_populate_kvm_info();
 
 	rate = arch_timer_get_cntfrq();
 	arch_timer_of_configure_rate(rate, np);
@@ -1550,7 +1557,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 	arch_timer_ppi[ARCH_TIMER_HYP_PPI] =
 		acpi_gtdt_map_ppi(ARCH_TIMER_HYP_PPI);
 
-	arch_timer_kvm_info.virtual_irq = arch_timer_ppi[ARCH_TIMER_VIRT_PPI];
+	arch_timer_populate_kvm_info();
 
 	/*
 	 * When probing via ACPI, we have no mechanism to override the sysreg

include/clocksource/arm_arch_timer.h

@@ -74,6 +74,7 @@ enum arch_timer_spi_nr {
 struct arch_timer_kvm_info {
 	struct timecounter timecounter;
 	int virtual_irq;
+	int physical_irq;
 };
 
 struct arch_timer_mem_frame {