intel-iommu: Avoid panic() for DRHD at address zero.

If the BIOS does something obviously stupid, like claiming that the
registers for the IOMMU are at physical address zero, then print a nasty
message and abort, rather than trying to set up the IOMMU and then later
panicking.

It's becoming more and more obvious that trusting this stuff to the BIOS
was a mistake.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 25a00ce4f24d..fa3a11365ec3 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -173,12 +173,21 @@ dmar_parse_one_drhd(struct acpi_dmar_header *header)
         struct dmar_drhd_unit *dmaru;
         int ret = 0;
 
+        drhd = (struct acpi_dmar_hardware_unit *)header;
+        if (!drhd->address) {
+                /* Promote an attitude of violence to a BIOS engineer today */
+                WARN(1, "Your BIOS is broken; DMAR reported at address zero!\n"
+                     "BIOS vendor: %s; Ver: %s; Product Version: %s\n",
+                     dmi_get_system_info(DMI_BIOS_VENDOR),
+                     dmi_get_system_info(DMI_BIOS_VERSION),
+                     dmi_get_system_info(DMI_PRODUCT_VERSION));
+                return -ENODEV;
+        }
         dmaru = kzalloc(sizeof(*dmaru), GFP_KERNEL);
         if (!dmaru)
                 return -ENOMEM;
 
         dmaru->hdr = header;
-        drhd = (struct acpi_dmar_hardware_unit *)header;
         dmaru->reg_base_addr = drhd->address;
         dmaru->segment = drhd->segment;
         dmaru->include_all = drhd->flags & 0x1; /* BIT0: INCLUDE_ALL */