[Qemu-devel] [PATCH] vfio/pci-quirks.c: Disable stolen memory for igd VFIO

[Xiong Zhang <xiong.y.zhang@intel.com>]

From: XiongZhang <xiong.y.zhang@intel.com>

If IGD isn't assigned at 00:02.0 in UPT and host bios enable stolen
memory, seabios won't reseave stolen memory in E820 for guest. Then
both Intel graphic driver and others in guest could use stolen
memory, this will generate system hang. So we should disable stolen
memory in this case.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99028
		https://bugs.freedesktop.org/show_bug.cgi?id=99025

Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
---
 hw/vfio/pci-quirks.c | 71 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 39 insertions(+), 32 deletions(-)

diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index 1e97bc4..3c03577 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -1364,17 +1364,44 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     uint32_t gmch;
     uint16_t cmd_orig, cmd;
 
-    /*
-     * This must be an Intel VGA device at address 00:02.0 for us to even
-     * consider enabling legacy mode.  The vBIOS has dependencies on the
-     * PCI bus address.
-     */
-    if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
-        !vfio_is_vga(vdev) || nr != 4 ||
-        &vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
-                                       0, PCI_DEVFN(0x2, 0))) {
-        return;
-    }
+	/* This must be an Intel VGA device. */
+	if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
+		!vfio_is_vga(vdev) || nr != 4)
+		return;
+
+	/*
+	 * IGD is not a standard, they like to change their specs often.  We
+	 * only attempt to support back to SandBridge and we hope that newer
+	 * devices maintain compatibility with generation 8.
+	 */
+	gen = igd_gen(vdev);
+	if (gen != 6 && gen != 8) {
+		error_report("IGD device %s is unsupported in legacy mode, "
+			     "try SandyBridge or newer", vdev->vbasedev.name);
+		return;
+	}
+	/*
+	 * If this isn't at address 00:02.0, bios won't reserv stolen
+	 * memory in E820, then others could use stolen memory. If guest
+	 * graphic driver still use stolen memory, system maybe hang.
+	 * so we set stolen memory size to 0 and guest graphic driver won't
+	 * use stolen memory.
+	 */
+	gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
+	gmch &= ~((gen < 8 ? 0x1f : 0xff) << (gen < 8 ? 3 : 8));
+
+	/* GMCH is read-only, emulated */
+	pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
+	pci_set_long(vdev->pdev.wmask + IGD_GMCH, 0);
+	pci_set_long(vdev->emulated_config_bits + IGD_GMCH, ~0);
+
+	/*
+	 * This must be at address 00:02.0 for us to even onsider enabling
+	 * legacy mode.  The vBIOS has dependencies on the PCI bus address.
+	 */
+	if (&vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
+					   0, PCI_DEVFN(0x2, 0)))
+		return;
 
     /*
      * We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
@@ -1391,18 +1418,6 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     }
 
     /*
-     * IGD is not a standard, they like to change their specs often.  We
-     * only attempt to support back to SandBridge and we hope that newer
-     * devices maintain compatibility with generation 8.
-     */
-    gen = igd_gen(vdev);
-    if (gen != 6 && gen != 8) {
-        error_report("IGD device %s is unsupported in legacy mode, "
-                     "try SandyBridge or newer", vdev->vbasedev.name);
-        return;
-    }
-
-    /*
      * Most of what we're doing here is to enable the ROM to run, so if
      * there's no ROM, there's no point in setting up this quirk.
      * NB. We only seem to get BIOS ROMs, so a UEFI VM would need CSM support.
@@ -1457,8 +1472,6 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         goto out;
     }
 
-    gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
-
     /*
      * If IGD VGA Disable is clear (expected) and VGA is not already enabled,
      * try to enable it.  Probably shouldn't be using legacy mode without VGA,
@@ -1526,12 +1539,11 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
      * when IVD (IGD VGA Disable) is clear, but the claim is that it's unused,
      * so let's not waste VM memory for it.
      */
-    gmch &= ~((gen < 8 ? 0x1f : 0xff) << (gen < 8 ? 3 : 8));
-
     if (vdev->igd_gms) {
         if (vdev->igd_gms <= 0x10) {
             gms_mb = vdev->igd_gms * 32;
             gmch |= vdev->igd_gms << (gen < 8 ? 3 : 8);
+			pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
         } else {
             error_report("Unsupported IGD GMS value 0x%x", vdev->igd_gms);
             vdev->igd_gms = 0;
@@ -1551,11 +1563,6 @@ static void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size",
                     bdsm_size, sizeof(*bdsm_size));
 
-    /* GMCH is read-only, emulated */
-    pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
-    pci_set_long(vdev->pdev.wmask + IGD_GMCH, 0);
-    pci_set_long(vdev->emulated_config_bits + IGD_GMCH, ~0);
-
     /* BDSM is read-write, emulated.  The BIOS needs to be able to write it */
     pci_set_long(vdev->pdev.config + IGD_BDSM, 0);
     pci_set_long(vdev->pdev.wmask + IGD_BDSM, ~0);
-- 
2.9.3