[PATCH v2] Xen: Use VGA Hooks to make VGA passthrough work on certain devices

[Julian Pidancet]

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.

v2: Ignore the case where Option ROMs are pre-deployed.
    Make vgahook_setup independent of wether the CB* variables are set.
    VGA hooks can be enabled on non-coreboot and non-Xen configurations.

Signed-off-by: Julian Pidancet 
---
 src/Kconfig    |    1 -
 src/coreboot.c |    2 +-
 src/vgahooks.c |   22 +++++++++++++++++++++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/Kconfig b/src/Kconfig
index cf0bff0..250663a 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -283,7 +283,6 @@ menu "BIOS interfaces"
             Support S3 resume handler.

config VGAHOOKS
-        depends on COREBOOT
         bool "Hardware specific VGA helpers"
         default y
         help
diff --git a/src/coreboot.c b/src/coreboot.c
index ee9dd8b..e328c15 100644
--- a/src/coreboot.c
+++ b/src/coreboot.c
@@ -117,7 +117,7 @@ find_cb_subtable(struct cb_header *cbh, u32 tag)
 }

static struct cb_memory *CBMemTable;
-const char *CBvendor, *CBpart;
+const char *CBvendor = "", *CBpart = "";

// Populate max ram and e820 map info by scanning for a coreboot table.
 static void
diff --git a/src/vgahooks.c b/src/vgahooks.c
index a8f667c..20a2e2e 100644
--- a/src/vgahooks.c
+++ b/src/vgahooks.c
@@ -186,11 +186,20 @@ 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;
     }
 }
@@ -206,6 +215,15 @@ intel_155f(struct bregs *regs)
 #define BOOT_DISPLAY_LCD2       (1 << 7)

static void
+intel_setup(struct pci_device *pci)
+{
+    VGAHookHandlerType = VH_INTEL;
+
+    IntelDisplayType = BOOT_DISPLAY_DEFAULT;
+    IntelDisplayId = 3;
+}
+
+static void
 roda_setup(struct pci_device *pci)
 {
     VGAHookHandlerType = VH_INTEL;
@@ -254,7 +272,7 @@ handle_155f(struct bregs *regs)
 void
 vgahook_setup(struct pci_device *pci)
 {
-    if (!CONFIG_VGAHOOKS || !CBvendor || !CBpart)
+    if (!CONFIG_VGAHOOKS)
         return;

if (strcmp(CBvendor, "KONTRON") == 0 && strcmp(CBpart, "986LCD-M") == 0)
@@ -265,4 +283,6 @@ vgahook_setup(struct pci_device *pci)
         roda_setup(pci);
     else if (pci->vendor == PCI_VENDOR_ID_VIA)
         via_setup(pci);
+    else if (pci->vendor == PCI_VENDOR_ID_INTEL)
+        intel_setup(pci);
 }