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@amd.com>
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@suse.com>
Committed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/drivers/passthrough/amd/iommu_init.c b/xen/drivers/passthrough/amd/iommu_init.c
index cdfdd2e83246f7569f0acbf354f8fd04d2312f21..780e2069c94208263360b88c7320b6cbfa21a6ca 100644 (file)
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -1120,12 +1120,45 @@ static int __init amd_iommu_setup_device_table(
     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(0, 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(0, 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;
+
     ivrs_bdf_entries = amd_iommu_get_ivrs_dev_entries();
 
     if ( !ivrs_bdf_entries )