We found some strange devices in HP C7000 and Huawei Storage Server. These
devices can not be enumerated by OS, but they still did DMA read/write
without OS management. Because iommu will not create the DMA mapping for
these devices, the DMA read/write will be blocked by iommu hardware.
Eg.
in HP C7000:
\-[0000:00]-+-00.0 Intel Corporation Xeon E5/Core i7 DMI2
+-01.0-[11]--
+-01.1-[02]--
+-02.0-[04]--+-00.0 Emulex Corporation OneConnect
10Gb NIC (be3)
| +-00.1 Emulex Corporation OneConnect 10Gb NIC
(be3)
| +-00.2 Emulex Corporation OneConnect 10Gb iSCSI
Initiator (be3)
| \-00.3 Emulex Corporation OneConnect 10Gb iSCSI
Initiator (be3)
+-02.1-[12]--
Kernel only found four devices in bus 0x04, but we found following DMA errors
in dmesg.
[ 1438.477262] DRHD: handling fault status reg 402
[ 1438.498278] DMAR:[DMA Write] Request device [04:00.4] fault addr bdf70000
[ 1438.498280] DMAR:[fault reason 02] Present bit in context entry is clear
[ 1438.566458] DMAR:[DMA Write] Request device [04:00.5] fault addr bdf70000
[ 1438.566460] DMAR:[fault reason 02] Present bit in context entry is clear
[ 1438.635211] DMAR:[DMA Write] Request device [04:00.6] fault addr bdf70000
[ 1438.635213] DMAR:[fault reason 02] Present bit in context entry is clear
[ 1438.703849] DMAR:[DMA Write] Request device [04:00.7] fault addr bdf70000
[ 1438.703851] DMAR:[fault reason 02] Present bit in context entry is clear
This patch add a kernel boot command parameter iommu=pt_force=domain:busnum
that based iommu identity mapping and force to create identity for all devfn in
the specific bus number to fix this issue.
Signed-off-by: Yijing Wang <[email protected]>
---
v1-v2: Documented to kernel-parameter, tested ok in the real broken platforms.
---
Documentation/kernel-parameters.txt | 2 +
arch/x86/include/asm/iommu.h | 2 +
arch/x86/kernel/pci-dma.c | 8 ++++++
drivers/iommu/intel-iommu.c | 42 +++++++++++++++++++++++++++++++++++
4 files changed, 54 insertions(+), 0 deletions(-)
diff --git a/Documentation/kernel-parameters.txt
b/Documentation/kernel-parameters.txt
index 5ae8608..d49a619 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1431,6 +1431,8 @@ bytes respectively. Such letter suffixes can also be
entirely omitted.
forcesac
soft
pt [x86, IA-64]
+ pt_force=[domain:bus] [x86] Force to create identity mapping
+ for all devfn in specific pci bus.
io7= [HW] IO7 for Marvel based alpha systems
diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h
index 345c99c..5e3a2d8 100644
--- a/arch/x86/include/asm/iommu.h
+++ b/arch/x86/include/asm/iommu.h
@@ -5,6 +5,8 @@ extern struct dma_map_ops nommu_dma_ops;
extern int force_iommu, no_iommu;
extern int iommu_detected;
extern int iommu_pass_through;
+extern int iommu_pt_force_bus;
+extern int iommu_pt_force_domain;
/* 10 seconds */
#define DMAR_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000)
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index a25e202..bf21d97 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -44,6 +44,8 @@ int iommu_detected __read_mostly = 0;
* guests and not for driver dma translation.
*/
int iommu_pass_through __read_mostly;
+int iommu_pt_force_bus = -1;
+int iommu_pt_force_domain = -1;
extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
@@ -146,6 +148,7 @@ void dma_generic_free_coherent(struct device *dev, size_t
size, void *vaddr,
*/
static __init int iommu_setup(char *p)
{
+ char *end;
iommu_merge = 1;
if (!p)
@@ -192,6 +195,11 @@ static __init int iommu_setup(char *p)
#endif
if (!strncmp(p, "pt", 2))
iommu_pass_through = 1;
+ if (!strncmp(p, "pt_force=", 9)) {
+ iommu_pass_through = 1;
+ iommu_pt_force_domain = simple_strtol(p+9, &end, 0);
+ iommu_pt_force_bus = simple_strtol(end+1, NULL, 0);
+ }
gart_parse_options(p);
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index d1f5caa..08eb5a0 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2705,6 +2705,48 @@ static int __init
iommu_prepare_static_identity_mapping(int hw)
return ret;
}
+ /* We found some strange devices in HP c7000 and other platforms, they
+ * can not be enumerated by OS, and they did DMA read/write without
+ * driver management. if we open iommu in these platforms, the DMA
read/write
+ * will be blocked by IOMMU hardware. Currently, we only create
identity mapping
+ * for the devices in OS. To fix this, add
iommu=pt_force=segment:busnum to
+ * force to do identity mapping for the specific bus.
+ */
+ if (iommu_pt_force_bus >= 0 && iommu_pt_force_bus >= 0) {
+ int found = 0;
+
+ iommu = NULL;
+ for_each_active_iommu(iommu, drhd) {
+ if (iommu_pt_force_domain != drhd->segment)
+ continue;
+
+ for_each_active_dev_scope(drhd->devices,
drhd->devices_cnt, i, dev) {
+ if (!dev_is_pci(dev))
+ continue;
+
+ pdev = to_pci_dev(dev);
+ if (pdev->bus->number == iommu_pt_force_bus ||
+ (pdev->subordinate
+ && pdev->subordinate->number
<= iommu_pt_force_bus
+ &&
pdev->subordinate->busn_res.end >= iommu_pt_force_bus)) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (drhd->include_all) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (found && iommu)
+ for (i = 0; i < 256; i++)
+ domain_context_mapping_one(si_domain, iommu,
iommu_pt_force_bus,
+ i, hw ?
CONTEXT_TT_PASS_THROUGH :
+ CONTEXT_TT_MULTI_LEVEL);
+ }
+
return 0;
}
--
1.7.1
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