i386: pci-assign: Fix MSI-X table size

The current code creates a whole page mmio region for the MSI-X table
size.

However, the page containing the MSI-X table may contain other registers
not related to MSI-X. Creating an mmio region for the whole page masks
such registers and may break drivers in the guest OS.

Since maximal number of entries is known, use that instead to deduce the
table size when setting up the mmio region.
Signed-off-by: NIdo Yariv <ido@wizery.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/i386/kvm/pci-assign.c

@@ -36,8 +36,6 @@
 #include "kvm_i386.h"
 #include "hw/pci/pci-assign.h"
 
-#define MSIX_PAGE_SIZE 0x1000
-
 /* From linux/ioport.h */
 #define IORESOURCE_IO       0x00000100  /* Resource type */
 #define IORESOURCE_MEM      0x00000200
@@ -122,6 +120,7 @@ typedef struct AssignedDevice {
     int *msi_virq;
     MSIXTableEntry *msix_table;
     hwaddr msix_table_addr;
+    uint16_t msix_table_size;
     uint16_t msix_max;
     MemoryRegion mmio;
     char *configfd_name;
@@ -1310,6 +1309,7 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev, Error **errp)
         bar_nr = msix_table_entry & PCI_MSIX_FLAGS_BIRMASK;
         msix_table_entry &= ~PCI_MSIX_FLAGS_BIRMASK;
         dev->msix_table_addr = pci_region[bar_nr].base_addr + msix_table_entry;
+        dev->msix_table_size = msix_max * sizeof(MSIXTableEntry);
         dev->msix_max = msix_max;
     }
 
@@ -1633,7 +1633,7 @@ static void assigned_dev_msix_reset(AssignedDevice *dev)
         return;
     }
 
-    memset(dev->msix_table, 0, MSIX_PAGE_SIZE);
+    memset(dev->msix_table, 0, dev->msix_table_size);
 
     for (i = 0, entry = dev->msix_table; i < dev->msix_max; i++, entry++) {
         entry->ctrl = cpu_to_le32(0x1); /* Masked */
@@ -1642,8 +1642,8 @@ static void assigned_dev_msix_reset(AssignedDevice *dev)
 
 static void assigned_dev_register_msix_mmio(AssignedDevice *dev, Error **errp)
 {
-    dev->msix_table = mmap(NULL, MSIX_PAGE_SIZE, PROT_READ|PROT_WRITE,
-                           MAP_ANONYMOUS|MAP_PRIVATE, 0, 0);
+    dev->msix_table = mmap(NULL, dev->msix_table_size, PROT_READ | PROT_WRITE,
+                           MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
     if (dev->msix_table == MAP_FAILED) {
         error_setg_errno(errp, errno, "failed to allocate msix_table");
         dev->msix_table = NULL;
@@ -1653,7 +1653,7 @@ static void assigned_dev_register_msix_mmio(AssignedDevice *dev, Error **errp)
     assigned_dev_msix_reset(dev);
 
     memory_region_init_io(&dev->mmio, OBJECT(dev), &assigned_dev_msix_mmio_ops,
-                          dev, "assigned-dev-msix", MSIX_PAGE_SIZE);
+                          dev, "assigned-dev-msix", dev->msix_table_size);
 }
 
 static void assigned_dev_unregister_msix_mmio(AssignedDevice *dev)
@@ -1662,7 +1662,7 @@ static void assigned_dev_unregister_msix_mmio(AssignedDevice *dev)
         return;
     }
 
-    if (munmap(dev->msix_table, MSIX_PAGE_SIZE) == -1) {
+    if (munmap(dev->msix_table, dev->msix_table_size) == -1) {
         error_report("error unmapping msix_table! %s", strerror(errno));
     }
     dev->msix_table = NULL;