Re: [Qemu-devel] [v3][PATCH 1/1] hw/pci-assign: split pci-assign.c

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

On Mon, Sep 01, 2014 at 06:56:55PM +0800, Chen, Tiejun wrote:
> On 2014/9/1 18:46, Michael S. Tsirkin wrote:
> >On Mon, Sep 01, 2014 at 06:36:47PM +0800, Tiejun Chen wrote:
> >>We will try to reuse assign_dev_load_option_rom in xen side, and
> >>especially its a good beginning to unify pci assign codes both on
> >>kvm and xen in the future.
> >>
> >>Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> >>---
> >>  hw/i386/kvm/pci-assign.c    | 46 +++++++++++++++++++++++++++++----------------
> >>  include/hw/pci/pci-assign.h | 16 ++++++++++++++++
> >>  2 files changed, 46 insertions(+), 16 deletions(-)
> >>  create mode 100644 include/hw/pci/pci-assign.h
> >>
> >>diff --git a/hw/i386/kvm/pci-assign.c b/hw/i386/kvm/pci-assign.c
> >>index 17c7d6dc..fdc7b64 100644
> >>--- a/hw/i386/kvm/pci-assign.c
> >>+++ b/hw/i386/kvm/pci-assign.c
> >>@@ -37,6 +37,7 @@
> >>  #include "hw/pci/pci.h"
> >>  #include "hw/pci/msi.h"
> >>  #include "kvm_i386.h"
> >>+#include "hw/pci/pci-assign.h"
> >>
> >>  #define MSIX_PAGE_SIZE 0x1000
> >>
> >>@@ -1896,37 +1897,39 @@ type_init(assign_register_types)
> >>   * load the corresponding ROM data to RAM. If an error occurs while loading an
> >>   * option ROM, we just ignore that option ROM and continue with the next one.
> >>   */
> >>-static void assigned_dev_load_option_rom(AssignedDevice *dev)
> >>+int pci_assign_dev_load_option_rom(PCIDevice *dev, struct Object *owner,
> >>+                                   void *ptr, unsigned int domain,
> >
> >ptr parameter seems unused.
> >
> >>+                                   unsigned int bus, unsigned int slot,
> >>+                                   unsigned int function)
> >>  {
> >>      char name[32], rom_file[64];
> >>      FILE *fp;
> >>      uint8_t val;
> >>      struct stat st;
> >>-    void *ptr;
> >>+    int size = 0;
> >>
> >>      /* If loading ROM from file, pci handles it */
> >>-    if (dev->dev.romfile || !dev->dev.rom_bar) {
> >>-        return;
> >>+    if (dev->romfile || !dev->rom_bar) {
> >>+        return -1;
> >>      }
> >>
> >>      snprintf(rom_file, sizeof(rom_file),
> >>               "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/rom",
> >>-             dev->host.domain, dev->host.bus, dev->host.slot,
> >>-             dev->host.function);
> >>+             domain, bus, slot, function);
> >>
> >>      if (stat(rom_file, &st)) {
> >>-        return;
> >>+        return -1;
> >>      }
> >>
> >>      if (access(rom_file, F_OK)) {
> >>          error_report("pci-assign: Insufficient privileges for %s", rom_file);
> >>-        return;
> >>+        return -1;
> >>      }
> >>
> >>      /* Write "1" to the ROM file to enable it */
> >>      fp = fopen(rom_file, "r+");
> >>      if (fp == NULL) {
> >>-        return;
> >>+        return -1;
> >>      }
> >>      val = 1;
> >>      if (fwrite(&val, 1, 1, fp) != 1) {
> >>@@ -1934,11 +1937,10 @@ static void assigned_dev_load_option_rom(AssignedDevice *dev)
> >>      }
> >>      fseek(fp, 0, SEEK_SET);
> >>
> >>-    snprintf(name, sizeof(name), "%s.rom",
> >>-            object_get_typename(OBJECT(dev)));
> >>-    memory_region_init_ram(&dev->dev.rom, OBJECT(dev), name, st.st_size);
> >>-    vmstate_register_ram(&dev->dev.rom, &dev->dev.qdev);
> >>-    ptr = memory_region_get_ram_ptr(&dev->dev.rom);
> >>+    snprintf(name, sizeof(name), "%s.rom", object_get_typename(owner));
> >>+    memory_region_init_ram(&dev->rom, owner, name, st.st_size);
> >>+    vmstate_register_ram(&dev->rom, &dev->qdev);
> >>+    ptr = memory_region_get_ram_ptr(&dev->rom);
> >>      memset(ptr, 0xff, st.st_size);
> >>
> >>      if (!fread(ptr, 1, st.st_size, fp)) {
> >>@@ -1949,8 +1951,9 @@ static void assigned_dev_load_option_rom(AssignedDevice *dev)
> >>          goto close_rom;
> >>      }
> >>
> >>-    pci_register_bar(&dev->dev, PCI_ROM_SLOT, 0, &dev->dev.rom);
> >>-    dev->dev.has_rom = true;
> >>+    pci_register_bar(dev, PCI_ROM_SLOT, 0, &dev->rom);
> >>+    dev->has_rom = true;
> >>+    size = st.st_size;
> >>  close_rom:
> >>      /* Write "0" to disable ROM */
> >>      fseek(fp, 0, SEEK_SET);
> >>@@ -1959,4 +1962,15 @@ close_rom:
> >>          DEBUG("%s\n", "Failed to disable pci-sysfs rom file");
> >>      }
> >>      fclose(fp);
> >>+
> >>+    return size;
> >>+}
> >>+
> >>+static void assigned_dev_load_option_rom(AssignedDevice *dev)
> >>+{
> >>+    void *ptr = NULL;
> >>+
> >
> >This is never modified, I don't think you need this
> >variable.
> >
> >>+    pci_assign_dev_load_option_rom(&dev->dev, OBJECT(dev), ptr,
> >>+                                   dev->host.domain, dev->host.bus,
> >>+                                   dev->host.slot, dev->host.function);
> >>  }
> 
> In patch 0/1, there's a little bit background for this usage in xen side :)

I still don't get it. the value you pass is never used.


> Currently we only support that as primary display device, so we need to copy
> vBIOS from BAR to 0xc0000. Here I picked some codes fragments up:
> 
> +static int get_vgabios(XenPCIPassthroughState *s, void *ptr,
> +                       XenHostPCIDevice *dev)
> +{
> +    int size = 0;
> +


this is wrong too, you don't need = 0 here.

> +    size = pci_assign_dev_load_option_rom(&s->dev, OBJECT(dev), ptr,
> +                                          dev->domain, dev->bus,
> +                                          dev->dev, dev->func);
> +
> +    return size;
> +}
> +
> +int xen_pt_setup_vga(XenPCIPassthroughState *s, XenHostPCIDevice *dev)
> +{
> +    void *bios = NULL;
> +    int bios_size = 0;

and here

> +    int rc = 0;
> +
> +    if (!is_vga_passthrough(dev)) {
> +        return rc;
> +    }
> +
> +    bios_size = get_vgabios(s, bios, dev);
> +    if (!bios || !bios_size) {
> +        XEN_PT_ERR(NULL, "VGA: getting VBIOS!\n");
> +        rc = -1;
> +        goto out;
> +    }
> +
> +    /* Currently we fixed this address as a primary. */
> +    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
> +out:
> +    g_free(bios);
> +    return rc;
> +}
> 
> Of course, if you have a better idea, please tell me.
> 
> Thanks
> Tiejun

don't initialize variables just to override them a couple
of lines down.