spapr: Move interrupt allocator to xics

The current allocator returns IRQ numbers from a pool and does not
support IRQs reuse in any form as it did not keep track of what it
previously returned, it only keeps the last returned IRQ. Some use
cases such as PCI hot(un)plug may require IRQ release and reallocation.

This moves an allocator from SPAPR to XICS.

This switches IRQ users to use new API.

This uses LSI/MSI flags to know if interrupt is allocated.

The interrupt release function will be posted as a separate patch.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 88 insertions, 0 deletions

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 634101ac23..6cd980a735 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -687,6 +687,94 @@ void xics_set_irq_type(XICSState *icp, int irq, bool lsi)
     ics_set_irq_type(ics, irq - ics->offset, lsi);
 }
 
+#define ICS_IRQ_FREE(ics, srcno)   \
+    (!((ics)->irqs[(srcno)].flags & (XICS_FLAGS_IRQ_MASK)))
+
+static int ics_find_free_block(ICSState *ics, int num, int alignnum)
+{
+    int first, i;
+
+    for (first = 0; first < ics->nr_irqs; first += alignnum) {
+        if (num > (ics->nr_irqs - first)) {
+            return -1;
+        }
+        for (i = first; i < first + num; ++i) {
+            if (!ICS_IRQ_FREE(ics, i)) {
+                break;
+            }
+        }
+        if (i == (first + num)) {
+            return first;
+        }
+    }
+
+    return -1;
+}
+
+int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi)
+{
+    ICSState *ics = &icp->ics[src];
+    int irq;
+
+    if (irq_hint) {
+        assert(src == xics_find_source(icp, irq_hint));
+        if (!ICS_IRQ_FREE(ics, irq_hint - ics->offset)) {
+            trace_xics_alloc_failed_hint(src, irq_hint);
+            return -1;
+        }
+        irq = irq_hint;
+    } else {
+        irq = ics_find_free_block(ics, 1, 1);
+        if (irq < 0) {
+            trace_xics_alloc_failed_no_left(src);
+            return -1;
+        }
+        irq += ics->offset;
+    }
+
+    ics_set_irq_type(ics, irq - ics->offset, lsi);
+    trace_xics_alloc(src, irq);
+
+    return irq;
+}
+
+/*
+ * Allocate block of consequtive IRQs, returns a number of the first.
+ * If align==true, aligns the first IRQ number to num.
+ */
+int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align)
+{
+    int i, first = -1;
+    ICSState *ics = &icp->ics[src];
+
+    assert(src == 0);
+    /*
+     * MSIMesage::data is used for storing VIRQ so
+     * it has to be aligned to num to support multiple
+     * MSI vectors. MSI-X is not affected by this.
+     * The hint is used for the first IRQ, the rest should
+     * be allocated continuously.
+     */
+    if (align) {
+        assert((num == 1) || (num == 2) || (num == 4) ||
+               (num == 8) || (num == 16) || (num == 32));
+        first = ics_find_free_block(ics, num, num);
+    } else {
+        first = ics_find_free_block(ics, num, 1);
+    }
+
+    if (first >= 0) {
+        for (i = first; i < first + num; ++i) {
+            ics_set_irq_type(ics, i, lsi);
+        }
+    }
+    first += ics->offset;
+
+    trace_xics_alloc_block(src, first, num, lsi, align);
+
+    return first;
+}
+
 /*
  * Guest interfaces
  */