[Intel-gfx] [IGDVFIO] [PATCH 4/8] RFC and help completing: Intel IGD Direct Assignment with VFIO

[Andrew Barnes]

hw/pci/pci.c

this patch adds:
* read / write host PCI config space

patch
---------------------

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 42995e6..041f6f1 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2,6 +2,8 @@
  * QEMU PCI bus manager
  *
  * Copyright (c) 2004 Fabrice Bellard
+ *    2014 Andrew Barnes <andy at outsideglobe.com> IGD Support
+ *        Temporarily extended to provide host config read/write.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
copy
  * of this software and associated documentation files (the "Software"),
to deal
@@ -37,9 +39,9 @@
 #include "exec/address-spaces.h"
 #include "hw/hotplug.h"

-//#define DEBUG_PCI
+/* #define DEBUG_PCI */
 #ifdef DEBUG_PCI
-# define PCI_DPRINTF(format, ...)       printf(format, ## __VA_ARGS__)
+# define PCI_DPRINTF(format, ...)       printf("pci:" format, ##
__VA_ARGS__)
 #else
 # define PCI_DPRINTF(format, ...)       do { } while (0)
 #endif
@@ -60,6 +62,81 @@ static Property pci_props[] = {
     DEFINE_PROP_END_OF_LIST()
 };

+/* Provides config reads from the host */
+uint32_t host_pci_read_config(int bus, int slot, int fn, uint32_t address,
int len)
+{
+    uint32_t val = 0;
+    int fd;
+    int domain = 0;
+    ssize_t ret;
+    char dir[128], name[128];
+
+    snprintf(dir, sizeof(dir), "/sys/bus/pci/devices/%04x:%02x:%02x.%x/",
+             domain, bus, slot, fn);
+    snprintf(name, sizeof(name), "%sconfig", dir);
+
+    fd = open(name, O_RDONLY);
+
+    if (fd >= 0)
+    {
+        do
+        {
+            ret = pread(fd,&val,len,address);
+        } while ((ret < 0) && (errno == EINTR || errno == EAGAIN));
+
+        if (ret != len)
+        {
+            PCI_DPRINTF("%s(%04x:%02x:%02x.%x, @0x%x, len=0x%x) %s ret=%zd
error=%d\n",
+                 __func__, 0000, bus, slot, fn, address, len, "pread
Failed",ret,errno);
+            val = (1UL << (len * 8)) - 1;
+        }
+    }
+    else
+    {
+        PCI_DPRINTF("%s(%04x:%02x:%02x.%x, @0x%x, len=0x%x) %s\n",
+                 __func__, 0000, bus, slot, fn, address, len, "Open
Failed");
+    }
+
+    PCI_DPRINTF("%s(%04x:%02x:%02x.%x, @0x%x, len=0x%x) %x\n",
+                 __func__, 0000, bus, slot, fn, address, len, val);
+    return val;
+}
+
+/* Provides config writes to the host*/
+void host_pci_write_config(int bus, int slot, int fn, uint32_t address,
int len, uint32_t val)
+{
+    int fd;
+    int domain = 0;
+    ssize_t ret;
+    char dir[128], name[128];
+
+    snprintf(dir, sizeof(dir), "/sys/bus/pci/devices/%04x:%02x:%02x.%x/",
+             domain, bus, slot, fn);
+    snprintf(name, sizeof(name), "%sconfig", dir);
+
+    fd = open(name, O_RDWR);
+
+    if (fd >= 0)
+    {
+        do
+        {
+            ret = pwrite(fd,&val,len,address);
+        } while ((ret < 0) && (errno == EINTR || errno == EAGAIN));
+
+
+        if (ret != len)
+        {
+            PCI_DPRINTF("%s(%04x:%02x:%02x.%x, @0x%x, len=0x%x) %x %s
ret=%zd error=%d\n",
+                 __func__, 0000, bus, slot, fn, address, len, val, "pread
Failed",ret,errno);
+        }
+    }
+    else
+    {
+        PCI_DPRINTF("%s(%04x:%02x:%02x.%x, @0x%x, len=0x%x) %s\n",
+                 __func__, 0000, bus, slot, fn, address, len, "Open
Failed");
+    }
+}
+
 static const VMStateDescription vmstate_pcibus = {
     .name = "PCIBUS",
     .version_id = 1,
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