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Re: [Qemu-devel] [PATCH v2 4/8] spapr: Move interrupt allocator to xics


From: Alexander Graf
Subject: Re: [Qemu-devel] [PATCH v2 4/8] spapr: Move interrupt allocator to xics
Date: Wed, 21 May 2014 10:47:20 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.5.0


On 21.05.14 10:46, Alexey Kardashevskiy wrote:
On 05/21/2014 06:34 PM, Alexander Graf wrote:
On 15.05.14 11:59, Alexey Kardashevskiy wrote:
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 <address@hidden>
---
   hw/intc/xics.c         | 88
++++++++++++++++++++++++++++++++++++++++++++++++++
   hw/ppc/spapr.c         | 67 --------------------------------------
   hw/ppc/spapr_events.c  |  2 +-
   hw/ppc/spapr_pci.c     |  6 ++--
   hw/ppc/spapr_vio.c     |  2 +-
   include/hw/ppc/spapr.h | 10 ------
   include/hw/ppc/xics.h  |  2 ++
   trace-events           |  4 +++
   8 files changed, 99 insertions(+), 82 deletions(-)

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 83a809e..fdcbb3a 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -689,6 +689,94 @@ 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));
Could this ever get triggered by a guest? Why don't we just fail as if the
IRQ wasn't available?
The @irq_hist is only used when the user specified IRQ in the command line,
this is why it is assert. And the guest never gets to choose IRQ number, it
receives numbers either via device tree (and QEMU puts those numbers there,
not SLOF) or ibm,change-msi (QEMU returns numbers).

Ok, it's safe then :).


Alex





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