[Qemu-devel] [PATCH v2 10/12] piix: do not raise irq while loading vmstate

[Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>]

This patch disables raising an irq while loading the state of PCI bridge.
The aim of this patch is preserving the same behavior while saving and
restoring the VM state. IRQ is not raised while saving the state of the bridge.
That's why the behavior of the restored system will differ from
the original one. This patch eliminates raising an irq and just restores
the calculated state fields in post_load function.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
---
 hw/pci-host/piix.c |   26 ++++++++++++++++++++++++--
 1 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index e0e0946..cd50435 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -409,7 +409,7 @@ static void piix3_set_irq_pic(PIIX3State *piix3, int pic_irq)
                      (pic_irq * PIIX_NUM_PIRQS))));
 }
 
-static void piix3_set_irq_level(PIIX3State *piix3, int pirq, int level)
+static void piix3_set_irq_level_internal(PIIX3State *piix3, int pirq, int level)
 {
     int pic_irq;
     uint64_t mask;
@@ -422,6 +422,18 @@ static void piix3_set_irq_level(PIIX3State *piix3, int pirq, int level)
     mask = 1ULL << ((pic_irq * PIIX_NUM_PIRQS) + pirq);
     piix3->pic_levels &= ~mask;
     piix3->pic_levels |= mask * !!level;
+}
+
+static void piix3_set_irq_level(PIIX3State *piix3, int pirq, int level)
+{
+    int pic_irq;
+
+    pic_irq = piix3->dev.config[PIIX_PIRQC + pirq];
+    if (pic_irq >= PIIX_NUM_PIC_IRQS) {
+        return;
+    }
+
+    piix3_set_irq_level_internal(piix3, pirq, level);
 
     piix3_set_irq_pic(piix3, pic_irq);
 }
@@ -527,7 +539,17 @@ static void piix3_reset(void *opaque)
 static int piix3_post_load(void *opaque, int version_id)
 {
     PIIX3State *piix3 = opaque;
-    piix3_update_irq_levels(piix3);
+    int pirq;
+
+    /* Update irq levels without raising an interrupt which
+       could be caused by piix3_update_irq_levels function.
+       Raising an irq will switch the system to the state
+       different to the saved one. */
+    piix3->pic_levels = 0;
+    for (pirq = 0; pirq < PIIX_NUM_PIRQS; pirq++) {
+        piix3_set_irq_level_internal(piix3, pirq,
+                            pci_bus_get_irq_level(piix3->dev.bus, pirq));
+    }
     return 0;
 }