intel-iommu: Cope with broken HP DC7900 BIOS

Yet another reason why trusting this stuff to the BIOS was a bad idea.
The HP DC7900 BIOS reports an iommu at an address which just returns all
ones, when VT-d is disabled in the BIOS.

Fix up the missing iounmap in the error paths while we're at it.

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

1 files changed, 18 insertions, 4 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 7b287cb38b7a..380b60e677e0 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -632,20 +632,31 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
         iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
         iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
 
+        if (iommu->cap == (uint64_t)-1 && iommu->ecap == (uint64_t)-1) {
+                /* Promote an attitude of violence to a BIOS engineer today */
+                WARN(1, "Your BIOS is broken; DMAR reported at address %llx returns all ones!\n"
+                     "BIOS vendor: %s; Ver: %s; Product Version: %s\n",
+                     drhd->reg_base_addr,
+                     dmi_get_system_info(DMI_BIOS_VENDOR),
+                     dmi_get_system_info(DMI_BIOS_VERSION),
+                     dmi_get_system_info(DMI_PRODUCT_VERSION));
+                goto err_unmap;
+        }
+
 #ifdef CONFIG_DMAR
         agaw = iommu_calculate_agaw(iommu);
         if (agaw < 0) {
                 printk(KERN_ERR
                        "Cannot get a valid agaw for iommu (seq_id = %d)\n",
                        iommu->seq_id);
-                goto error;
+                goto err_unmap;
         }
         msagaw = iommu_calculate_max_sagaw(iommu);
         if (msagaw < 0) {
                 printk(KERN_ERR
                         "Cannot get a valid max agaw for iommu (seq_id = %d)\n",
                         iommu->seq_id);
-                goto error;
+                goto err_unmap;
         }
 #endif
         iommu->agaw = agaw;
@@ -665,7 +676,7 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
         }
 
         ver = readl(iommu->reg + DMAR_VER_REG);
-        pr_debug("IOMMU %llx: ver %d:%d cap %llx ecap %llx\n",
+        pr_info("IOMMU %llx: ver %d:%d cap %llx ecap %llx\n",
                 (unsigned long long)drhd->reg_base_addr,
                 DMAR_VER_MAJOR(ver), DMAR_VER_MINOR(ver),
                 (unsigned long long)iommu->cap,
@@ -675,7 +686,10 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 
         drhd->iommu = iommu;
         return 0;
-error:
+
+ err_unmap:
+        iounmap(iommu->reg);
+ error:
         kfree(iommu);
         return -1;
 }