arm_gic: Keep track of SGI sources

Right now the arm gic emulation doesn't keep track of the source of an
SGI (which apparently Linux guests don't use, or they're fine with
assuming CPU 0 always).

Add the necessary matrix on the GICState structure and maintain the data
when setting and clearing the pending state of an IRQ and make the state
visible to the guest.

Note that we always choose to present the source as the lowest-numbered
CPU in case multiple cores have signalled the same SGI number to a core
on the system.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 96 insertions, 14 deletions

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index 77519c0ad5..6550292be5 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -151,6 +151,8 @@ static void gic_set_irq(void *opaque, int irq, int level)
         target = cm;
     }
 
+    assert(irq >= GIC_NR_SGIS);
+
     if (level == GIC_TEST_LEVEL(irq, cm)) {
         return;
     }
@@ -177,21 +179,48 @@ static void gic_set_running_irq(GICState *s, int cpu, int irq)
 
 uint32_t gic_acknowledge_irq(GICState *s, int cpu)
 {
-    int new_irq;
+    int ret, irq, src;
     int cm = 1 << cpu;
-    new_irq = s->current_pending[cpu];
-    if (new_irq == 1023
-            || GIC_GET_PRIORITY(new_irq, cpu) >= s->running_priority[cpu]) {
+    irq = s->current_pending[cpu];
+    if (irq == 1023
+            || GIC_GET_PRIORITY(irq, cpu) >= s->running_priority[cpu]) {
         DPRINTF("ACK no pending IRQ\n");
         return 1023;
     }
-    s->last_active[new_irq][cpu] = s->running_irq[cpu];
-    /* Clear pending flags for both level and edge triggered interrupts.
-       Level triggered IRQs will be reasserted once they become inactive.  */
-    GIC_CLEAR_PENDING(new_irq, GIC_TEST_MODEL(new_irq) ? ALL_CPU_MASK : cm);
-    gic_set_running_irq(s, cpu, new_irq);
-    DPRINTF("ACK %d\n", new_irq);
-    return new_irq;
+    s->last_active[irq][cpu] = s->running_irq[cpu];
+
+    if (s->revision == REV_11MPCORE) {
+        /* Clear pending flags for both level and edge triggered interrupts.
+         * Level triggered IRQs will be reasserted once they become inactive.
+         */
+        GIC_CLEAR_PENDING(irq, GIC_TEST_MODEL(irq) ? ALL_CPU_MASK : cm);
+        ret = irq;
+    } else {
+        if (irq < GIC_NR_SGIS) {
+            /* Lookup the source CPU for the SGI and clear this in the
+             * sgi_pending map.  Return the src and clear the overall pending
+             * state on this CPU if the SGI is not pending from any CPUs.
+             */
+            assert(s->sgi_pending[irq][cpu] != 0);
+            src = ctz32(s->sgi_pending[irq][cpu]);
+            s->sgi_pending[irq][cpu] &= ~(1 << src);
+            if (s->sgi_pending[irq][cpu] == 0) {
+                GIC_CLEAR_PENDING(irq, GIC_TEST_MODEL(irq) ? ALL_CPU_MASK : cm);
+            }
+            ret = irq | ((src & 0x7) << 10);
+        } else {
+            /* Clear pending state for both level and edge triggered
+             * interrupts. (level triggered interrupts with an active line
+             * remain pending, see gic_test_pending)
+             */
+            GIC_CLEAR_PENDING(irq, GIC_TEST_MODEL(irq) ? ALL_CPU_MASK : cm);
+            ret = irq;
+        }
+    }
+
+    gic_set_running_irq(s, cpu, irq);
+    DPRINTF("ACK %d\n", irq);
+    return ret;
 }
 
 void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val)
@@ -353,6 +382,22 @@ static uint32_t gic_dist_readb(void *opaque, hwaddr offset)
             if (GIC_TEST_EDGE_TRIGGER(irq + i))
                 res |= (2 << (i * 2));
         }
+    } else if (offset < 0xf10) {
+        goto bad_reg;
+    } else if (offset < 0xf30) {
+        if (s->revision == REV_11MPCORE || s->revision == REV_NVIC) {
+            goto bad_reg;
+        }
+
+        if (offset < 0xf20) {
+            /* GICD_CPENDSGIRn */
+            irq = (offset - 0xf10);
+        } else {
+            irq = (offset - 0xf20);
+            /* GICD_SPENDSGIRn */
+        }
+
+        res = s->sgi_pending[irq][cpu];
     } else if (offset < 0xfe0) {
         goto bad_reg;
     } else /* offset >= 0xfe0 */ {
@@ -527,9 +572,31 @@ static void gic_dist_writeb(void *opaque, hwaddr offset,
                 GIC_CLEAR_EDGE_TRIGGER(irq + i);
             }
         }
-    } else {
+    } else if (offset < 0xf10) {
         /* 0xf00 is only handled for 32-bit writes.  */
         goto bad_reg;
+    } else if (offset < 0xf20) {
+        /* GICD_CPENDSGIRn */
+        if (s->revision == REV_11MPCORE || s->revision == REV_NVIC) {
+            goto bad_reg;
+        }
+        irq = (offset - 0xf10);
+
+        s->sgi_pending[irq][cpu] &= ~value;
+        if (s->sgi_pending[irq][cpu] == 0) {
+            GIC_CLEAR_PENDING(irq, 1 << cpu);
+        }
+    } else if (offset < 0xf30) {
+        /* GICD_SPENDSGIRn */
+        if (s->revision == REV_11MPCORE || s->revision == REV_NVIC) {
+            goto bad_reg;
+        }
+        irq = (offset - 0xf20);
+
+        GIC_SET_PENDING(irq, 1 << cpu);
+        s->sgi_pending[irq][cpu] |= value;
+    } else {
+        goto bad_reg;
     }
     gic_update(s);
     return;
@@ -553,6 +620,7 @@ static void gic_dist_writel(void *opaque, hwaddr offset,
         int cpu;
         int irq;
         int mask;
+        int target_cpu;
 
         cpu = gic_get_current_cpu(s);
         irq = value & 0x3ff;
@@ -572,6 +640,12 @@ static void gic_dist_writel(void *opaque, hwaddr offset,
             break;
         }
         GIC_SET_PENDING(irq, mask);
+        target_cpu = ctz32(mask);
+        while (target_cpu < GIC_NCPU) {
+            s->sgi_pending[irq][target_cpu] |= (1 << cpu);
+            mask &= ~(1 << target_cpu);
+            target_cpu = ctz32(mask);
+        }
         gic_update(s);
         return;
     }
diff --git a/hw/intc/arm_gic_common.c b/hw/intc/arm_gic_common.c
index e4fc65028a..92de7f8e0d 100644
--- a/hw/intc/arm_gic_common.c
+++ b/hw/intc/arm_gic_common.c
@@ -58,8 +58,8 @@ static const VMStateDescription vmstate_gic_irq_state = {
 
 static const VMStateDescription vmstate_gic = {
     .name = "arm_gic",
-    .version_id = 4,
-    .minimum_version_id = 4,
+    .version_id = 5,
+    .minimum_version_id = 5,
     .pre_save = gic_pre_save,
     .post_load = gic_post_load,
     .fields = (VMStateField[]) {
@@ -71,6 +71,7 @@ static const VMStateDescription vmstate_gic = {
         VMSTATE_UINT8_2DARRAY(priority1, GICState, GIC_INTERNAL, GIC_NCPU),
         VMSTATE_UINT8_ARRAY(priority2, GICState, GIC_MAXIRQ - GIC_INTERNAL),
         VMSTATE_UINT16_2DARRAY(last_active, GICState, GIC_MAXIRQ, GIC_NCPU),
+        VMSTATE_UINT8_2DARRAY(sgi_pending, GICState, GIC_NR_SGIS, GIC_NCPU),
         VMSTATE_UINT16_ARRAY(priority_mask, GICState, GIC_NCPU),
         VMSTATE_UINT16_ARRAY(running_irq, GICState, GIC_NCPU),
         VMSTATE_UINT16_ARRAY(running_priority, GICState, GIC_NCPU),
diff --git a/include/hw/intc/arm_gic_common.h b/include/hw/intc/arm_gic_common.h
index 8a2aa00cee..d2e0c2f5f1 100644
--- a/include/hw/intc/arm_gic_common.h
+++ b/include/hw/intc/arm_gic_common.h
@@ -55,6 +55,13 @@ typedef struct GICState {
     uint8_t priority1[GIC_INTERNAL][GIC_NCPU];
     uint8_t priority2[GIC_MAXIRQ - GIC_INTERNAL];
     uint16_t last_active[GIC_MAXIRQ][GIC_NCPU];
+    /* For each SGI on the target CPU, we store 8 bits
+     * indicating which source CPUs have made this SGI
+     * pending on the target CPU. These correspond to
+     * the bytes in the GIC_SPENDSGIR* registers as
+     * read by the target CPU.
+     */
+    uint8_t sgi_pending[GIC_NR_SGIS][GIC_NCPU];
 
     uint16_t priority_mask[GIC_NCPU];
     uint16_t running_irq[GIC_NCPU];