[Xen-changelog] [xen stable-4.8] VT-d: don't panic/warn on iommu=no-igfx

[patchbot@xxxxxxx]

commit f914884320bfc1325ac0e4dc630fa39efe46dde5
Author:     Rusty Bird <rustybird@xxxxxxxxxxxxxxx>
AuthorDate: Mon Aug 28 11:47:41 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Aug 28 11:47:41 2017 +0200

    VT-d: don't panic/warn on iommu=no-igfx
    
    When operating on an Intel graphics device, iommu_enable_translation()
    panicked (force_iommu==1) or warned (force_iommu==0) about the BIOS if
    is_igd_vt_enabled_quirk() returned 0. That's good if the actual BIOS
    problem has been detected. But since commit 1463411, returning 0 could
    also happen if the user simply passed "iommu=no-igfx", in which case
    bailing out with an info message (instead of a panic/warning) would be
    more appropriate.
    
    The panic broke the combination "iommu=force,no-igfx", and also the case
    where "iommu=no-igfx" is passed but force_iommu=1 is set automatically
    by x2apic_bsp_setup().
    
    Move the iommu_igfx check from is_igd_vt_enabled_quirk() into its only
    caller iommu_enable_translation(), and tweak the logic.
    
    Signed-off-by: Rusty Bird <rustybird@xxxxxxxxxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    master commit: dbf2a768565d8b79c65471a3d3b982b2874d6492
    master date: 2017-08-03 12:40:25 +0200
---
 xen/drivers/passthrough/vtd/iommu.c  | 22 ++++++++++++++++------
 xen/drivers/passthrough/vtd/quirks.c |  3 ---
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index b856ae1..4e73439 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -747,14 +747,24 @@ static void iommu_enable_translation(struct 
acpi_drhd_unit *drhd)
     unsigned long flags;
     struct iommu *iommu = drhd->iommu;
 
-    if ( is_igd_drhd(drhd) && !is_igd_vt_enabled_quirk() ) 
+    if ( is_igd_drhd(drhd) )
     {
-        if ( force_iommu )
-            panic("BIOS did not enable IGD for VT properly, crash Xen for 
security purpose");
+        if ( !iommu_igfx )
+        {
+            printk(XENLOG_INFO VTDPREFIX
+                   "Passed iommu=no-igfx option.  Disabling IGD VT-d 
engine.\n");
+            return;
+        }
 
-        printk(XENLOG_WARNING VTDPREFIX
-               "BIOS did not enable IGD for VT properly.  Disabling IGD VT-d 
engine.\n");
-        return;
+        if ( !is_igd_vt_enabled_quirk() )
+        {
+            if ( force_iommu )
+                panic("BIOS did not enable IGD for VT properly, crash Xen for 
security purpose");
+
+            printk(XENLOG_WARNING VTDPREFIX
+                   "BIOS did not enable IGD for VT properly.  Disabling IGD 
VT-d engine.\n");
+            return;
+        }
     }
 
     /* apply platform specific errata workarounds */
diff --git a/xen/drivers/passthrough/vtd/quirks.c 
b/xen/drivers/passthrough/vtd/quirks.c
index 91f96ac..5bbbd96 100644
--- a/xen/drivers/passthrough/vtd/quirks.c
+++ b/xen/drivers/passthrough/vtd/quirks.c
@@ -70,9 +70,6 @@ int is_igd_vt_enabled_quirk(void)
 {
     u16 ggc;
 
-    if ( !iommu_igfx )
-        return 0;
-
     if ( !IS_ILK(ioh_id) )
         return 1;
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8

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