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@openmailbox.org>
Acked-by: Kevin Tian <kevin.tian@intel.com>
master commit: dbf2a768565d8b79c65471a3d3b982b2874d6492
master date: 2017-08-03 12:40:25 +0200

diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index b856ae14ce387a826e32e3329e9b02d28bd00cf7..4e734394e3db61d92af6d5f17c2147e7315d4c55 100644 (file)
--- 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 91f96acb69501f185a9da6cf1a121047d7ef678c..5bbbd96d51b530c763e805bf444e64c243516845 100644 (file)
--- 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;