[PATCH 14/15] iommu/vt-d: Add a helper to retrieve PID address

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

From: Thomas Gleixner <tglx@linutronix.de>

Physical address of the Intel posted interrupt descriptor (PID) is needed
when programming interrupt remapping table entry (IRTE) for posted mode.

PID is per-CPU, this patch adds a helper function to retrieve the target
CPU's PID address based on the effective affinity mask of the interrupt.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>

---
v1: Added a warning if the effective affinity mask is not set up
---
 drivers/iommu/intel/irq_remapping.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index fa719936b44e..01df65dca1d5 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -19,6 +19,7 @@
 #include <asm/cpu.h>
 #include <asm/irq_remapping.h>
 #include <asm/pci-direct.h>
+#include <asm/posted_intr.h>
 
 #include "iommu.h"
 #include "../irq_remapping.h"
@@ -1126,6 +1127,19 @@ struct irq_remap_ops intel_irq_remap_ops = {
 	.enable_faulting	= enable_drhd_fault_handling,
 };
 
+#ifdef CONFIG_X86_POSTED_MSI
+
+static phys_addr_t get_pi_desc_addr(struct irq_data *irqd)
+{
+	int cpu = cpumask_first(irq_data_get_effective_affinity_mask(irqd));
+
+	if (WARN_ON(cpu >= nr_cpu_ids))
+		return 0;
+
+	return __pa(per_cpu_ptr(&posted_interrupt_desc, cpu));
+}
+#endif
+
 static void intel_ir_reconfigure_irte(struct irq_data *irqd, bool force)
 {
 	struct intel_ir_data *ir_data = irqd->chip_data;
-- 
2.25.1