[PATCH 0/3] Use VGA Hooks to make Xen VGA passthrough work on certain devices

From: Julian Pidancet <[e-mail]>

The Intel gfx VGA option ROM on certain platforms requires the 155f50 BIOS function to be
implemented (even if it does nothing), to work properly. This series of patch allow
VGA passthrough on Xen to work on these platforms.

An example of these platform is the Dell Lattitude E6410 laptop, on which these patchs were
tested.

Julian Pidancet (3):
  vgahooks: Allow usage of VGA hooks in the Xen case
  vgahooks: Register 155f vga hooks for Xen Intel passthrough devices
  vgahooks: Create 155f50 hook.

 src/Kconfig      |    2 +-
 src/optionroms.c |    9 +++++++++
 src/vgahooks.c   |   29 ++++++++++++++++++++++++++++-
 3 files changed, 38 insertions(+), 2 deletions(-)

-- 
Julian Pidancet

[PATCH 1/3] vgahooks: Allow usage of VGA hooks in the Xen case

From: Julian Pidancet <[e-mail]>

This patch enables the VGAHOOKS config option if the BIOS is configured
for Xen.
In the Xen VGA passthrough case, the option ROM can be extracted from
the physical device by hvmloader and pre-deployed for seabios. This
patch also allows setting up VGA hooks in case the VGA option ROM is
already deployed by hvmloader.

Signed-off-by: Julian Pidancet <[e-mail]>
---
 src/Kconfig      |    2 +-
 src/optionroms.c |    9 +++++++++
 2 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/src/Kconfig b/src/Kconfig
index 4270014..9ea48bb 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -283,7 +283,7 @@ menu "BIOS interfaces"
             Support S3 resume handler.
 
     config VGAHOOKS
-        depends on COREBOOT
+        depends on COREBOOT || XEN
         bool "Hardware specific VGA helpers"
         default y
         help
diff --git a/src/optionroms.c b/src/optionroms.c
index 27cfffd..62de40e 100644
--- a/src/optionroms.c
+++ b/src/optionroms.c
@@ -427,6 +427,15 @@ vga_setup(void)
     ScreenAndDebug = romfile_loadint("etc/screen-and-debug", 1);
 
     if (CONFIG_OPTIONROMS_DEPLOYED) {
+        /* Setup VGA hooks */
+        struct pci_device *pci;
+        foreachpci(pci) {
+            if (!is_pci_vga(pci))
+                continue;
+            vgahook_setup(pci);
+            break;
+        }
+
         // Option roms are already deployed on the system.
         init_optionrom((void*)BUILD_ROM_START, 0, 1);
     } else {
-- 
Julian Pidancet

[PATCH 2/3] vgahooks: Register 155f vga hooks for Xen Intel passthrough devices

From: Julian Pidancet <[e-mail]>

Some Intel VGA option ROMs require some 155f hooks implemented in the
BIOS.

Signed-off-by: Julian Pidancet <[e-mail]>
---
 src/vgahooks.c |   20 +++++++++++++++++++-
 1 files changed, 19 insertions(+), 1 deletions(-)

diff --git a/src/vgahooks.c b/src/vgahooks.c
index a8f667c..ca12e31 100644
--- a/src/vgahooks.c
+++ b/src/vgahooks.c
@@ -11,6 +11,7 @@
 #include "pci_ids.h" // PCI_VENDOR_ID_VIA
 #include "util.h" // handle_155f
 #include "config.h" // CONFIG_*
+#include "xen.h" // usingXen
 
 #define VH_VIA 1
 #define VH_INTEL 2
@@ -228,6 +229,15 @@ getac_setup(struct pci_device *pci)
 {
 }
 
+static void
+xen_vgapt_setup(struct pci_device *pci)
+{
+    if (pci->vendor == 0x8086 && pci->class == 0x300) {
+        VGAHookHandlerType = VH_INTEL;
+        IntelDisplayType = BOOT_DISPLAY_DEFAULT;
+        IntelDisplayId = 3;
+    }
+}
 
 /****************************************************************
  * Entry and setup
@@ -254,7 +264,15 @@ handle_155f(struct bregs *regs)
 void
 vgahook_setup(struct pci_device *pci)
 {
-    if (!CONFIG_VGAHOOKS || !CBvendor || !CBpart)
+    if (!CONFIG_VGAHOOKS)
+        return;
+
+    if (usingXen()) {
+        xen_vgapt_setup(pci);
+        return;
+    }
+
+    if (!CBvendor || !CBpart)
         return;
 
     if (strcmp(CBvendor, "KONTRON") == 0 && strcmp(CBpart, "986LCD-M") == 0)
-- 
Julian Pidancet

[PATCH 3/3] vgahooks: Create 155f50 hook.

From: Julian Pidancet <[e-mail]>

This patch adds a 155f50 hook which is mandatory for VGA option ROM to
work on some platforms. This allows an Intel GFX device to be passed
through to a Xen VM on some laptops using a Dell BIOS (Tested
successfully on a Dell Lattitude E6410 laptop).

Signed-off-by: Julian Pidancet <[e-mail]>
---
 src/vgahooks.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/src/vgahooks.c b/src/vgahooks.c
index ca12e31..3ae50e5 100644
--- a/src/vgahooks.c
+++ b/src/vgahooks.c
@@ -187,11 +187,20 @@ intel_155f40(struct bregs *regs)
 }
 
 static void
+intel_155f50(struct bregs *regs)
+{
+    /* Mandatory hook on some Dell laptops */
+    regs->ax = 0x005f;
+    set_success(regs);
+}
+
+static void
 intel_155f(struct bregs *regs)
 {
     switch (regs->al) {
     case 0x35: intel_155f35(regs); break;
     case 0x40: intel_155f40(regs); break;
+    case 0x50: intel_155f50(regs); break;
     default:   handle_155fXX(regs); break;
     }
 }
-- 
Julian Pidancet