[PATCH v5 4/7] xen/arm: gic: Use the correct CPU ID

[Julien Grall <julien.grall@linaro.org>]

The GIC mapping of CPU interfaces does not necessarily match the logical
CPU numbering.

When Xen wants to send an SGI to specific CPU, it needs to use the GIC CPU ID.
It can be retrieved from ITARGETSR0, in fact when this field is read, the GIC
will return a value that corresponds only to the processor reading the register.
So Xen can use the PPI 0 to initialize the mapping.

Signed-off-by: Julien Grall <julien.grall@linaro.org>

---
    Changes in v5:
        - Remove the per_cpu ASSERT.

    Changes in v4:
        - Make logical and between the cpumask given in arguments and
        cpu_possible_map.
        - Make sure the per_cpu is initialized
        - Add comment restriction for gic_set_irq_properties

    Changes in v3:
        - Correctly create the mask in gic_cpu_mask

    Changes in v2:
        - Use per-cpu variable instead of an array
        - Add comment for NR_GIC_CPU_IF
---
 xen/arch/arm/gic.c |   45 +++++++++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index b969d23..05685cd 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -57,6 +57,31 @@ static DEFINE_PER_CPU(uint64_t, lr_mask);
 
 static unsigned nr_lrs;
 
+/* The GIC mapping of CPU interfaces does not necessarily match the
+ * logical CPU numbering. Let's use mapping as returned by the GIC
+ * itself
+ */
+static DEFINE_PER_CPU(u8, gic_cpu_id);
+
+/* Maximum cpu interface per GIC */
+#define NR_GIC_CPU_IF 8
+
+static unsigned int gic_cpu_mask(const cpumask_t *cpumask)
+{
+    unsigned int cpu;
+    unsigned int mask = 0;
+    cpumask_t possible_mask;
+
+    cpumask_and(&possible_mask, cpumask, &cpu_possible_map);
+    for_each_cpu(cpu, &possible_mask)
+    {
+        ASSERT(cpu < NR_GIC_CPU_IF);
+        mask |= per_cpu(gic_cpu_id, cpu);
+    }
+
+    return mask;
+}
+
 unsigned int gic_number_lines(void)
 {
     return gic.lines;
@@ -182,16 +207,18 @@ static hw_irq_controller gic_guest_irq_type = {
     .set_affinity = gic_irq_set_affinity,
 };
 
-/* needs to be called with gic.lock held */
+/*
+ * - needs to be called with gic.lock held
+ * - needs to be called with a valid cpu_mask, ie each cpu in the mask has
+ * already called gic_cpu_init
+ */
 static void gic_set_irq_properties(unsigned int irq, bool_t level,
                                    const cpumask_t *cpu_mask,
                                    unsigned int priority)
 {
     volatile unsigned char *bytereg;
     uint32_t cfg, edgebit;
-    unsigned int mask = cpumask_bits(cpu_mask)[0];
-
-    ASSERT(!(mask & ~0xff)); /* Target bitmap only support 8 CPUS */
+    unsigned int mask = gic_cpu_mask(cpu_mask);
 
     /* Set edge / level */
     cfg = GICD[GICD_ICFGR + irq / 16];
@@ -300,6 +327,8 @@ static void __cpuinit gic_cpu_init(void)
 {
     int i;
 
+    this_cpu(gic_cpu_id) = GICD[GICD_ITARGETSR] & 0xff;
+
     /* The first 32 interrupts (PPI and SGI) are banked per-cpu, so
      * even though they are controlled with GICD registers, they must
      * be set up here with the other per-cpu state. */
@@ -431,13 +460,13 @@ void __init gic_init(void)
 
 void send_SGI_mask(const cpumask_t *cpumask, enum gic_sgi sgi)
 {
-    unsigned long mask = cpumask_bits(cpumask)[0];
+    unsigned int mask = 0;
+    cpumask_t online_mask;
 
     ASSERT(sgi < 16); /* There are only 16 SGIs */
 
-    mask &= cpumask_bits(&cpu_online_map)[0];
-
-    ASSERT(mask < 0x100); /* The target bitmap only supports 8 CPUs */
+    cpumask_and(&online_mask, cpumask, &cpu_online_map);
+    mask = gic_cpu_mask(&online_mask);
 
     dsb();
 
-- 
1.7.10.4