[Qemu-devel] [PATCHv2 3/3] pci: interrupt disable bit support

["Michael S. Tsirkin" <mst@redhat.com>]

Interrupt disable bit is mandatory in PCI spec.
Implement it to make devices spec compliant.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/pci.c |   29 +++++++++++++++++++++++++++--
 hw/pci.h |    1 +
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/hw/pci.c b/hw/pci.c
index f83ea93..6542c20 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -520,7 +520,8 @@ static void pci_init_wmask(PCIDevice *dev)
     dev->wmask[PCI_CACHE_LINE_SIZE] = 0xff;
     dev->wmask[PCI_INTERRUPT_LINE] = 0xff;
     pci_set_word(dev->wmask + PCI_COMMAND,
-                 PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER);
+                 PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
+                 PCI_COMMAND_INTX_DISABLE);
 
     memset(dev->wmask + PCI_CONFIG_HEADER_SIZE, 0xff,
            config_size - PCI_CONFIG_HEADER_SIZE);
@@ -940,6 +941,25 @@ static void pci_update_mappings(PCIDevice *d)
     }
 }
 
+static inline int pci_irq_disabled(PCIDevice *d)
+{
+    return pci_get_word(d->config + PCI_COMMAND) & PCI_COMMAND_INTX_DISABLE;
+}
+
+/* Called after interrupt disabled field update in config space,
+ * assert/deassert interrupts if necessary.
+ * Gets original interrupt disable bit value (before update). */
+static void pci_update_irq_disabled(PCIDevice *d, int was_irq_disabled)
+{
+    int i, disabled = pci_irq_disabled(d);
+    if (disabled == was_irq_disabled)
+        return;
+    for (i = 0; i < PCI_NUM_PINS; ++i) {
+        int state = pci_irq_state(d, i);
+        pci_change_irq_level(d, i, disabled ? -state : state);
+    }
+}
+
 uint32_t pci_default_read_config(PCIDevice *d,
                                  uint32_t address, int len)
 {
@@ -952,7 +972,7 @@ uint32_t pci_default_read_config(PCIDevice *d,
 
 void pci_default_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
 {
-    int i;
+    int i, was_irq_disabled = pci_irq_disabled(d);
     uint32_t config_size = pci_config_size(d);
 
     for (i = 0; i < l && addr + i < config_size; val >>= 8, ++i) {
@@ -964,6 +984,9 @@ void pci_default_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
         ranges_overlap(addr, l, PCI_ROM_ADDRESS1, 4) ||
         range_covers_byte(addr, l, PCI_COMMAND))
         pci_update_mappings(d);
+
+    if (range_covers_byte(addr, l, PCI_COMMAND))
+        pci_update_irq_disabled(d, was_irq_disabled);
 }
 
 /***********************************************************/
@@ -981,6 +1004,8 @@ static void pci_set_irq(void *opaque, int irq_num, int level)
 
     pci_set_irq_state(pci_dev, irq_num, level);
     pci_update_irq_status(pci_dev);
+    if (pci_irq_disabled(pci_dev))
+        return;
     pci_change_irq_level(pci_dev, irq_num, change);
 }
 
diff --git a/hw/pci.h b/hw/pci.h
index dc9b860..d279e3f 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -101,6 +101,7 @@ typedef struct PCIIORegion {
 #define  PCI_COMMAND_IO		0x1	/* Enable response in I/O space */
 #define  PCI_COMMAND_MEMORY	0x2	/* Enable response in Memory space */
 #define  PCI_COMMAND_MASTER	0x4	/* Enable bus master */
+#define  PCI_COMMAND_INTX_DISABLE 0x400 /* INTx Emulation Disable */
 #define PCI_STATUS              0x06    /* 16 bits */
 #define  PCI_STATUS_INTERRUPT   0x08
 #define PCI_REVISION_ID         0x08    /* 8 bits  */
-- 
1.6.5.2.143.g8cc62