[Qemu-devel] [6091] PCI: Mask writes to RO bits in the status reg of PCI config space

[Qemu-devel] [6091] PCI: Mask writes to RO bits in the status reg of PCI config space

[Aurelien Jarno]

Revision: 6091
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6091
Author:   aurel32
Date:     2008-12-18 22:43:33 +0000 (Thu, 18 Dec 2008)

Log Message:
-----------
PCI: Mask writes to RO bits in the status reg of PCI config space

The Status register in the PCI config space has some read-only bits.
Any writes to those bits should be masked out.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

Modified Paths:
--------------
    trunk/hw/pci.c
    trunk/hw/pci.h

Modified: trunk/hw/pci.c
===================================================================
--- trunk/hw/pci.c	2008-12-18 22:43:25 UTC (rev 6090)
+++ trunk/hw/pci.c	2008-12-18 22:43:33 UTC (rev 6091)
@@ -381,6 +381,7 @@
             case 0x0b:
             case 0x0e:
             case 0x10 ... 0x27: /* base */
+            case 0x2c ... 0x2f: /* read-only subsystem ID & vendor ID */
             case 0x30 ... 0x33: /* rom */
             case 0x3d:
                 can_write = 0;
@@ -402,6 +403,7 @@
             case 0x0a:
             case 0x0b:
             case 0x0e:
+            case 0x2c ... 0x2f: /* read-only subsystem ID & vendor ID */
             case 0x38 ... 0x3b: /* rom */
             case 0x3d:
                 can_write = 0;
@@ -413,6 +415,15 @@
             break;
         }
         if (can_write) {
+            /* Mask out writes to reserved bits in registers */
+            switch (addr) {
+            case 0x06:
+                val &= ~PCI_STATUS_RESERVED_MASK_LO;
+                break;
+            case 0x07:
+                val &= ~PCI_STATUS_RESERVED_MASK_HI;
+                break;
+            }
             d->config[addr] = val;
         }
         if (++addr > 0xff)

Modified: trunk/hw/pci.h
===================================================================
--- trunk/hw/pci.h	2008-12-18 22:43:25 UTC (rev 6090)
+++ trunk/hw/pci.h	2008-12-18 22:43:33 UTC (rev 6091)
@@ -54,6 +54,21 @@
 #define PCI_MIN_GNT		0x3e	/* 8 bits */
 #define PCI_MAX_LAT		0x3f	/* 8 bits */
 
+/* Bits in the PCI Status Register (PCI 2.3 spec) */
+#define PCI_STATUS_RESERVED1	0x007
+#define PCI_STATUS_INT_STATUS	0x008
+#define PCI_STATUS_CAPABILITIES	0x010
+#define PCI_STATUS_66MHZ	0x020
+#define PCI_STATUS_RESERVED2	0x040
+#define PCI_STATUS_FAST_BACK	0x080
+#define PCI_STATUS_DEVSEL	0x600
+
+#define PCI_STATUS_RESERVED_MASK_LO (PCI_STATUS_RESERVED1 | \
+                PCI_STATUS_INT_STATUS | PCI_STATUS_CAPABILITIES | \
+                PCI_STATUS_66MHZ | PCI_STATUS_RESERVED2 | PCI_STATUS_FAST_BACK)
+
+#define PCI_STATUS_RESERVED_MASK_HI (PCI_STATUS_DEVSEL >> 8)
+
 struct PCIDevice {
     /* PCI config space */
     uint8_t config[256];