[PATCH v2 4/6] pci-assign: Properly handle more overlapping accesses

[Jan Kiszka <jan.kiszka@xxxxxxxxxxx>]

Ensure that accesses exceeding PCI_CAPABILITY_LIST and
PCI_INTERRUPT_LINE+PIN hit the real device in areas we do not
virtualize. Again, we do not optimize these checks and accesses a lot,
they are considered to be slow paths.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 hw/device-assignment.c |   34 +++++++++++++++++++++++++++++-----
 1 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/hw/device-assignment.c b/hw/device-assignment.c
index cea072e..37c77e3 100644
--- a/hw/device-assignment.c
+++ b/hw/device-assignment.c
@@ -442,7 +442,29 @@ static void assigned_dev_pci_write_config(PCIDevice *d, uint32_t address,
         ranges_overlap(address, len, PCI_INTERRUPT_LINE, 2)) {
         /* used for update-mappings (BAR emulation) */
         pci_default_write_config(d, address, val, len);
-        return;
+
+        /* Ensure that writes to overlapping areas we don't virtualize still
+         * hit the device. */
+        switch (address) {
+        case PCI_CAPABILITY_LIST:
+            if (len > 1) {
+                len -= 1;
+                address += 1;
+                val >>= 8;
+                break; /* continue writing to the device */
+            }
+            return;
+        case PCI_INTERRUPT_LINE:
+            if (len > 2) {
+                len -= 2;
+                address += 2;
+                val >>= 16;
+                break; /* continue writing to the device */
+            }
+            return;
+        default:
+            return;
+        }
     }
 
     DEBUG("NON BAR (%x.%x): address=%04x val=0x%08x len=%d\n",
@@ -467,7 +489,7 @@ again:
 static uint32_t assigned_dev_pci_read_config(PCIDevice *d, uint32_t address,
                                              int len)
 {
-    uint32_t val = 0;
+    uint32_t val = 0, virt_val;
     int fd;
     ssize_t ret;
     AssignedDevice *pci_dev = DO_UPCAST(AssignedDevice, dev, d);
@@ -484,12 +506,10 @@ static uint32_t assigned_dev_pci_read_config(PCIDevice *d, uint32_t address,
      *  - vendor & device ID
      *  - base address registers
      *  - ROM base address & capability pointer
-     *  - interrupt line & pin
      */
     if (ranges_overlap(address, len, PCI_VENDOR_ID, 4) ||
         ranges_overlap(address, len, PCI_BASE_ADDRESS_0, 24) ||
-        ranges_overlap(address, len, PCI_ROM_ADDRESS, 5) ||
-        ranges_overlap(address, len, PCI_INTERRUPT_LINE, 2)) {
+        ranges_overlap(address, len, PCI_ROM_ADDRESS, 4)) {
         val = pci_default_read_config(d, address, len);
         DEBUG("(%x.%x): address=%04x val=0x%08x len=%d\n",
               (d->devfn >> 3) & 0x1F, (d->devfn & 0x7), address, val, len);
@@ -523,6 +543,10 @@ do_log:
                          address, len, PCI_COMMAND, 0xffff);
     }
 
+    virt_val = pci_default_read_config(d, address, len);
+    val = merge_bits(val, virt_val, address, len, PCI_CAPABILITY_LIST, 0xff);
+    val = merge_bits(val, virt_val, address, len, PCI_INTERRUPT_LINE, 0xffff);
+
     if (!pci_dev->cap.available) {
         /* kill the special capabilities */
         if (address == PCI_COMMAND && len == 4) {
-- 
1.7.1

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