IOMMU: properly check whether interrupt remapping is enabled

... rather than the IOMMU as a whole.

That in turn required to make sure iommu_intremap gets properly
cleared when the respective initialization fails (or isn't being
done at all).

Along with making sure interrupt remapping doesn't get inconsistently
enabled on some IOMMUs and not on others in the VT-d code, this in turn
allowed quite a bit of cleanup on the VT-d side (removed from the
backport).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: "Zhang, Xiantao" <xiantao.zhang@intel.com>
master changeset: fae0372140befb88d890a30704a8ec058c902af8
master date: 2013-03-25 14:28:31 +0100

4 files changed, 12 insertions, 4 deletions

diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index ef332fb11e..ef3e4bdb12 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -201,7 +201,7 @@ static void read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
         BUG();
     }
 
-    if ( iommu_enabled )
+    if ( iommu_intremap )
         iommu_read_msi_from_ire(entry, msg);
 }
 
@@ -222,7 +222,7 @@ static void write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 {
     entry->msg = *msg;
 
-    if ( iommu_enabled )
+    if ( iommu_intremap )
     {
         ASSERT(msg != &entry->msg);
         iommu_update_ire_from_msi(entry, msg);
@@ -438,7 +438,7 @@ int msi_free_irq(struct msi_desc *entry)
     }
 
     /* Free the unused IRTE if intr remap enabled */
-    if ( iommu_enabled )
+    if ( iommu_intremap )
         iommu_update_ire_from_msi(entry, NULL);
 
     list_del(&entry->list);
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 456014af95..cf506e2ecd 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -323,6 +323,8 @@ int __init iommu_setup(void)
         rc = iommu_hardware_setup();
         iommu_enabled = (rc == 0);
     }
+    if ( !iommu_enabled )
+        iommu_intremap = 0;
 
     if ( (force_iommu && !iommu_enabled) ||
          (force_intremap && !iommu_intremap) )
@@ -339,9 +341,12 @@ int __init iommu_setup(void)
     }
     printk("I/O virtualisation %sabled\n", iommu_enabled ? "en" : "dis");
     if ( iommu_enabled )
+    {
         printk(" - Dom0 mode: %s\n",
                iommu_passthrough ? "Passthrough" :
                iommu_dom0_strict ? "Strict" : "Relaxed");
+        printk("Interrupt remapping %sabled\n", iommu_intremap ? "en" : "dis");
+    }
 
     return rc;
 }
diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index c218ec3af8..22e757c3db 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2101,6 +2101,9 @@ static int init_vtd_hw(void)
                 break;
             }
         }
+        if ( !iommu_intremap )
+            for_each_drhd_unit ( drhd )
+                disable_intremap(drhd->iommu);
     }
 
     /*
diff --git a/xen/include/asm-x86/io_apic.h b/xen/include/asm-x86/io_apic.h
index 1b42f85d8f..bbb6f3869f 100644
--- a/xen/include/asm-x86/io_apic.h
+++ b/xen/include/asm-x86/io_apic.h
@@ -129,7 +129,7 @@ struct IO_APIC_route_entry {
 extern struct mpc_config_ioapic mp_ioapics[MAX_IO_APICS];
 
 /* Only need to remap ioapic RTE (reg: 10~3Fh) */
-#define ioapic_reg_remapped(reg) (iommu_enabled && ((reg) >= 0x10))
+#define ioapic_reg_remapped(reg) (iommu_intremap && ((reg) >= 0x10))
 
 static inline unsigned int __io_apic_read(unsigned int apic, unsigned int reg)
 {