[Xen-changelog] [xen-4.1-testing] AMD, IOMMU: Disable IOMMU if SATA Combined mode is on

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Boris Ostrovsky <boris.ostrovsky@xxxxxxx>
# Date 1360074971 -3600
# Node ID 5c0fe82d6060292d2eb2b1834b064eca2447d25f
# Parent  cac6ae5e5dc68e9ca4e80bcfff04a19dcb3e3113
AMD,IOMMU: Disable IOMMU if SATA Combined mode is on

AMD's SP5100 chipset can be placed into SATA Combined mode
that may cause prevent dom0 from booting when IOMMU is
enabled and per-device interrupt remapping table is used.
While SP5100 erratum 28 requires BIOSes to disable this mode,
some may still use it.

This patch checks whether this mode is on and, if per-device
table is in use, disables IOMMU.

This is XSA-36 / CVE-2013-0153.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxx>

Flipped operands of && in amd_iommu_init() to make the message issued
by amd_sp5100_erratum28() match reality (when amd_iommu_perdev_intremap
is zero, there's really no point in calling the function).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
xen-unstable changeset: 26518:e379a23b0465
xen-unstable date: Tue Feb  5 14:21:25 UTC 2013
---


diff -r cac6ae5e5dc6 -r 5c0fe82d6060 xen/drivers/passthrough/amd/iommu_init.c
--- a/xen/drivers/passthrough/amd/iommu_init.c  Tue Feb 05 15:35:44 2013 +0100
+++ b/xen/drivers/passthrough/amd/iommu_init.c  Tue Feb 05 15:36:11 2013 +0100
@@ -897,12 +897,45 @@ static int __init amd_iommu_setup_device
     return 0;
 }
 
+/* Check whether SP5100 SATA Combined mode is on */
+static bool_t __init amd_sp5100_erratum28(void)
+{
+    u32 bus, id;
+    u16 vendor_id, dev_id;
+    u8 byte;
+
+    for (bus = 0; bus < 256; bus++)
+    {
+        id = pci_conf_read32(bus, 0x14, 0, PCI_VENDOR_ID);
+
+        vendor_id = id & 0xffff;
+        dev_id = (id >> 16) & 0xffff;
+
+        /* SP5100 SMBus module sets Combined mode on */
+        if (vendor_id != 0x1002 || dev_id != 0x4385)
+            continue;
+
+        byte = pci_conf_read8(bus, 0x14, 0, 0xad);
+        if ( (byte >> 3) & 1 )
+        {
+            printk(XENLOG_WARNING "AMD-Vi: SP5100 erratum 28 detected, 
disabling IOMMU.\n"
+                   "If possible, disable SATA Combined mode in BIOS or contact 
your vendor for BIOS update.\n");
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
 int __init amd_iommu_init(void)
 {
     struct amd_iommu *iommu;
 
     BUG_ON( !iommu_found() );
 
+    if ( amd_iommu_perdev_intremap && amd_sp5100_erratum28() )
+        goto error_out;
+
     irq_to_iommu = xmalloc_array(struct amd_iommu *, nr_irqs);
     if ( irq_to_iommu == NULL )
         goto error_out;

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