[xen stable-4.16] VT-d: constrain IGD check

[patchbot@xxxxxxx]

commit 4d42cc4d25c35ca381370a1fa0b45350723d1308
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Mar 21 13:52:20 2023 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Mar 21 13:52:20 2023 +0100

    VT-d: constrain IGD check
    
    Marking a DRHD as controlling an IGD isn't very sensible without
    checking that at the very least it's a graphics device that lives at
    0000:00:02.0. Re-use the reading of the class-code to control both the
    clearing of "gfx_only" and the setting of "igd_drhd_address".
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    master commit: f8c4317295fa1cde1a81779b7e362651c084efb8
    master date: 2023-03-14 10:44:08 +0100
---
 xen/drivers/passthrough/vtd/dmar.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/dmar.c 
b/xen/drivers/passthrough/vtd/dmar.c
index 33a12b2ae9..9ec49936b8 100644
--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -391,15 +391,12 @@ static int __init acpi_parse_dev_scope(
 
             if ( drhd )
             {
-                if ( (seg == 0) && (bus == 0) && (path->dev == 2) &&
-                     (path->fn == 0) )
-                    igd_drhd_address = drhd->address;
-
-                if ( gfx_only &&
-                     pci_conf_read8(PCI_SBDF(seg, bus, path->dev, path->fn),
+                if ( pci_conf_read8(PCI_SBDF(seg, bus, path->dev, path->fn),
                                     PCI_CLASS_DEVICE + 1) != 0x03
                                     /* PCI_BASE_CLASS_DISPLAY */ )
                     gfx_only = false;
+                else if ( !seg && !bus && path->dev == 2 && !path->fn )
+                    igd_drhd_address = drhd->address;
             }
 
             break;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16