[Xen-devel] [PATCH] libxl: Add AHCI support for upstream qemu

[Fabio Fantoni <fabio.fantoni@xxxxxxx>]

Usage:
ahci=0|1 (default=0)

If enabled adds ich9 disk controller in ahci mode and uses it with
upstream qemu to emulate disks instead of ide.
It doesn't support cdroms which still using ide (cdroms will use
"-device ide-cd" as new qemu parameter)
Ahci requires new qemu parameter but for now other emulated disks cases
remains with old ones (I did it in other patch, not needed by this one)
I did it as libxl parameter disabled by default to avoid possible
problems:
- with save/restore/migration (restoring with ahci a domU that was with
ide instead)
- windows < 8 without pv drivers (a registry key change is needed for
AHCI<->IDE change FWIK to avoid possible blue screen)
- windows XP or older that many not support ahci by default.
Setting AHCI with libxl parameter and default to disabled seems the best
solution.
AHCI increase hvm domUs boot performance. On linux hvm domU I saw up to
only 20% of the previous total boot time, whereas boot time decrease a
lot on W7 domUs for most of boots I have done. Small difference in boot
time compared to ide mode on W8 and newer (probably other xen
improvements or fixes are needed not ahci related)

Signed-off-by: Fabio Fantoni <fabio.fantoni@xxxxxxx>
---
 docs/man/xl.cfg.pod.5       |  9 +++++++++
 tools/libxl/libxl.h         | 10 ++++++++++
 tools/libxl/libxl_create.c  |  1 +
 tools/libxl/libxl_dm.c      | 10 +++++++++-
 tools/libxl/libxl_types.idl |  1 +
 tools/libxl/xl_cmdimpl.c    |  1 +
 6 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index a3e0e2e..7e16123 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -904,6 +904,15 @@ default is B<cd>.
 
 =back
 
+=item B<ahci=[0|1]>
+
+If enabled adds ich9 disk controller in ahci mode and uses it with
+upstream qemu to emulate disks instead of ide. It decrease boot time but
+may be not supported by default in windows xp and older windows.
+The default is disabled (0).
+
+=back
+
 =head3 Paging
 
 The following options control the mechanisms used to virtualise guest
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 0a7913b..6a3677d 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -596,6 +596,16 @@ typedef struct libxl__ctx libxl_ctx;
 #define LIBXL_HAVE_SPICE_STREAMINGVIDEO 1
 
 /*
+ * LIBXL_HAVE_AHCI
+ *
+ * If defined, then the u.hvm structure will contain a boolean type:
+ * ahci. This value defines if ahci support is present.
+ *
+ * If this is not defined, the ahci support is ignored.
+ */
+#define LIBXL_HAVE_AHCI 1
+
+/*
  * LIBXL_HAVE_DOMAIN_CREATE_RESTORE_PARAMS 1
  *
  * If this is defined, libxl_domain_create_restore()'s API has changed to
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 86384d2..8ca2481 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -331,6 +331,7 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         libxl_defbool_setdefault(&b_info->u.hvm.nested_hvm,         false);
         libxl_defbool_setdefault(&b_info->u.hvm.usb,                false);
         libxl_defbool_setdefault(&b_info->u.hvm.xen_platform_pci,   true);
+        libxl_defbool_setdefault(&b_info->u.hvm.ahci,               false);
 
         libxl_defbool_setdefault(&b_info->u.hvm.spice.enable, false);
         if (!libxl_defbool_val(b_info->u.hvm.spice.enable) &&
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 33f9ce6..93f191a 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -818,6 +818,8 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
     flexarray_append(dm_args, libxl__sprintf(gc, "%"PRId64, ram_size));
 
     if (b_info->type == LIBXL_DOMAIN_TYPE_HVM) {
+        if (libxl_defbool_val(b_info->u.hvm.ahci))
+            flexarray_append_pair(dm_args, "-device", "ahci,id=ahci0");
         for (i = 0; i < num_disks; i++) {
             int disk, part;
             int dev_number =
@@ -872,7 +874,13 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
                     drive = libxl__sprintf
                         (gc, 
"file=%s,if=scsi,bus=0,unit=%d,format=%s,cache=writeback",
                          pdev_path, disk, format);
-                else if (disk < 4)
+                else if (disk < 6 && libxl_defbool_val(b_info->u.hvm.ahci)){
+                    flexarray_vappend(dm_args, "-drive",
+                        
GCSPRINTF("file=%s,if=none,id=ahcidisk-%d,format=%s,cache=writeback",
+                        pdev_path, disk, format), "-device", 
GCSPRINTF("ide-hd,bus=ahci0.%d,unit=0,drive=ahcidisk-%d",
+                        disk, disk), NULL);
+                    continue;
+                }else if (disk < 4)
                     drive = libxl__sprintf
                         (gc, 
"file=%s,if=ide,index=%d,media=disk,format=%s,cache=writeback",
                          pdev_path, disk, format);
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 23f27d4..f107689 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -439,6 +439,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("nested_hvm",       libxl_defbool),
                                        ("smbios_firmware",  string),
                                        ("acpi_firmware",    string),
+                                       ("ahci",             libxl_defbool),
                                        ("nographic",        libxl_defbool),
                                        ("vga",              
libxl_vga_interface_info),
                                        ("vnc",              libxl_vnc_info),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index c858068..74b473e 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -2216,6 +2216,7 @@ skip_vfb:
         xlu_cfg_replace_string (config, "soundhw", &b_info->u.hvm.soundhw, 0);
         xlu_cfg_get_defbool(config, "xen_platform_pci",
                             &b_info->u.hvm.xen_platform_pci, 0);
+        xlu_cfg_get_defbool(config, "ahci", &b_info->u.hvm.ahci, 0);
 
         if(b_info->u.hvm.vnc.listen
            && b_info->u.hvm.vnc.display
-- 
1.9.1


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