[Xen-changelog] [xen stable-4.1] AMD IOMMU: allow disabling only interrupt remapping when certain IVRS consistency checks fail

[patchbot@xxxxxxx]

commit 842a6cedc61eabe5731ef192bf39dad66403d0c6
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Apr 2 12:31:36 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 2 12:31:36 2013 +0200

    AMD IOMMU: allow disabling only interrupt remapping when certain IVRS 
consistency checks fail
    
    After some more thought on the XSA-36 and specifically the comments we
    got regarding disabling the IOMMU in this situation altogether making
    things worse instead of better, I came to the conclusion that we can
    actually restrict the action in affected cases to just disabling
    interrupt remapping. That doesn't make the situation worse than prior
    to the XSA-36 fixes (where interrupt remapping didn't really protect
    domains from one another), but allows at least DMA isolation to still
    be utilized.
    
    To do so, disabling of interrupt remapping must be explicitly requested
    on the command line - respective checks will then be skipped.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx>
    master changeset: 92b8bc03bd4b582cb524db51494d0dba7607e7ac
    master date: 2013-03-25 16:55:22 +0100
---
 xen/drivers/passthrough/amd/iommu_acpi.c |    5 ++++-
 xen/drivers/passthrough/amd/iommu_init.c |    5 +++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu_acpi.c 
b/xen/drivers/passthrough/amd/iommu_acpi.c
index eb9c13c..7352438 100644
--- a/xen/drivers/passthrough/amd/iommu_acpi.c
+++ b/xen/drivers/passthrough/amd/iommu_acpi.c
@@ -664,6 +664,9 @@ static u16 __init parse_ivhd_device_special(
         return dev_length;
     }
 
+    if ( !iommu_intremap )
+        return dev_length;
+
     /*
      * Some BIOSes have IOAPIC broken entries so we check for IVRS
      * consistency here --- whether entry's IOAPIC ID is valid and
@@ -902,7 +905,7 @@ static int __init parse_ivrs_table(struct acpi_table_header 
*_table)
     }
 
     /* Each IO-APIC must have been mentioned in the table. */
-    for ( apic = 0; !error && apic < nr_ioapics; ++apic )
+    for ( apic = 0; !error && iommu_intremap && apic < nr_ioapics; ++apic )
     {
         if ( !nr_ioapic_registers[apic] ||
              ioapic_bdf[IO_APIC_ID(apic)].pin_setup )
diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
b/xen/drivers/passthrough/amd/iommu_init.c
index 31acec9..fcb7e87 100644
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -971,7 +971,8 @@ int __init amd_iommu_init(void)
 
     BUG_ON( !iommu_found() );
 
-    if ( amd_iommu_perdev_intremap && amd_sp5100_erratum28() )
+    if ( iommu_intremap && amd_iommu_perdev_intremap &&
+         amd_sp5100_erratum28() )
         goto error_out;
 
     irq_to_iommu = xmalloc_array(struct amd_iommu *, nr_irqs);
@@ -991,7 +992,7 @@ int __init amd_iommu_init(void)
         goto error_out;
 
     /* initialize io-apic interrupt remapping entries */
-    if ( amd_iommu_setup_ioapic_remapping() != 0 )
+    if ( iommu_intremap && amd_iommu_setup_ioapic_remapping() != 0 )
         goto error_out;
 
     /* allocate and initialize a global device table shared by all iommus */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.1

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