[patch 51/58] intel-iommu: Avoid panic() for DRHD at address zero.

[Greg KH]

2.6.29-stable review patch.  If anyone has any objections, please let us know.

------------------

From: David Woodhouse <dwmw2@xxxxxxxxxxxxx>

(cherry picked from commit e523b38e2f568af58baa13120a994cbf24e6dee0)

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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/pci/dmar.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -170,12 +170,21 @@ dmar_parse_one_drhd(struct acpi_dmar_hea
 	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->include_all = drhd->flags & 0x1; /* BIT0: INCLUDE_ALL */
 


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