AMD IOMMU: allow command line overrides for broken IVRS tables

With there being so many systems with broken ACPI tables, and with it
generally being known what's wrong with those tables, give people a
handle to overcome the resulting disabling of their IOMMUs.

Inspired by Linux side patches providing similar functionality.

Suggested-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-By: Sander Eikelenboom <linux@eikelenboom.it>
Acked-by: Keir Fraser <keir@xen.org>
Acked-by: Suravee Suthikulpanit <suravee.suthikulapanit@amd.com>

1 files changed, 70 insertions, 18 deletions

diff --git a/xen/drivers/passthrough/amd/iommu_acpi.c b/xen/drivers/passthrough/amd/iommu_acpi.c
index c903f9385c..89b359c455 100644
--- a/xen/drivers/passthrough/amd/iommu_acpi.c
+++ b/xen/drivers/passthrough/amd/iommu_acpi.c
@@ -633,6 +633,50 @@ static u16 __init parse_ivhd_device_extended_range(
     return dev_length;
 }
 
+static __initdata DECLARE_BITMAP(ioapic_cmdline, ARRAY_SIZE(ioapic_sbdf));
+
+static void __init parse_ivrs_ioapic(char *str)
+{
+    const char *s = str;
+    unsigned long id;
+    unsigned int seg, bus, dev, func;
+
+    ASSERT(*s == '[');
+    id = simple_strtoul(s + 1, &s, 0);
+    if ( id >= ARRAY_SIZE(ioapic_sbdf) || *s != ']' || *++s != '=' )
+        return;
+
+    s = parse_pci(s + 1, &seg, &bus, &dev, &func);
+    if ( !s || *s )
+        return;
+
+    ioapic_sbdf[id].bdf = PCI_BDF(bus, dev, func);
+    ioapic_sbdf[id].seg = seg;
+    __set_bit(id, ioapic_cmdline);
+}
+custom_param("ivrs_ioapic[", parse_ivrs_ioapic);
+
+static void __init parse_ivrs_hpet(char *str)
+{
+    const char *s = str;
+    unsigned long id;
+    unsigned int seg, bus, dev, func;
+
+    ASSERT(*s == '[');
+    id = simple_strtoul(s + 1, &s, 0);
+    if ( id != (typeof(hpet_sbdf.id))id || *s != ']' || *++s != '=' )
+        return;
+
+    s = parse_pci(s + 1, &seg, &bus, &dev, &func);
+    if ( !s || *s )
+        return;
+
+    hpet_sbdf.bdf = PCI_BDF(bus, dev, func);
+    hpet_sbdf.seg = seg;
+    hpet_sbdf.cmdline = 1;
+}
+custom_param("ivrs_hpet[", parse_ivrs_hpet);
+
 static u16 __init parse_ivhd_device_special(
     const struct acpi_ivrs_device8c *special, u16 seg,
     u16 header_length, u16 block_length, struct amd_iommu *iommu)
@@ -681,7 +725,10 @@ static u16 __init parse_ivhd_device_special(
                 return 0;
             }
 
-            if ( ioapic_sbdf[special->handle].pin_2_idx )
+            if ( test_bit(special->handle, ioapic_cmdline) )
+                AMD_IOMMU_DEBUG("IVHD: Command line override present for IO-APIC %#x\n",
+                                special->handle);
+            else if ( ioapic_sbdf[special->handle].pin_2_idx )
             {
                 if ( ioapic_sbdf[special->handle].bdf == bdf &&
                      ioapic_sbdf[special->handle].seg == seg )
@@ -724,14 +771,18 @@ static u16 __init parse_ivhd_device_special(
         break;
     case ACPI_IVHD_HPET:
         /* set device id of hpet */
-        if ( hpet_sbdf.iommu )
+        if ( hpet_sbdf.iommu ||
+             (hpet_sbdf.cmdline && hpet_sbdf.id != special->handle) )
         {
             printk(XENLOG_WARNING "Only one IVHD HPET entry is supported\n");
             break;
         }
         hpet_sbdf.id = special->handle;
-        hpet_sbdf.bdf = bdf;
-        hpet_sbdf.seg = seg;
+        if ( !hpet_sbdf.cmdline )
+        {
+            hpet_sbdf.bdf = bdf;
+            hpet_sbdf.seg = seg;
+        }
         hpet_sbdf.iommu = iommu;
         break;
     default:
@@ -942,22 +993,23 @@ static int __init parse_ivrs_table(struct acpi_table_header *table)
              ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx )
             continue;
 
-        printk(XENLOG_ERR "IVHD Error: no information for IO-APIC %#x\n",
-               IO_APIC_ID(apic));
-        if ( amd_iommu_perdev_intremap )
-            error = -ENXIO;
+        if ( !test_bit(IO_APIC_ID(apic), ioapic_cmdline) )
+        {
+            printk(XENLOG_ERR "IVHD Error: no information for IO-APIC %#x\n",
+                   IO_APIC_ID(apic));
+            if ( amd_iommu_perdev_intremap )
+                return -ENXIO;
+        }
+
+        ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx = xmalloc_array(
+            u16, nr_ioapic_entries[apic]);
+        if ( ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx )
+            memset(ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx, -1,
+                   nr_ioapic_entries[apic] * sizeof(*ioapic_sbdf->pin_2_idx));
         else
         {
-            ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx = xmalloc_array(
-                u16, nr_ioapic_entries[apic]);
-            if ( ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx )
-                memset(ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx, -1,
-                       nr_ioapic_entries[apic] * sizeof(*ioapic_sbdf->pin_2_idx));
-            else
-            {
-                printk(XENLOG_ERR "IVHD Error: Out of memory\n");
-                error = -ENOMEM;
-            }
+            printk(XENLOG_ERR "IVHD Error: Out of memory\n");
+            error = -ENOMEM;
         }
     }