On 8/11/2014 12:43 AM, Alex Williamson wrote:
> On Mon, 2014-08-11 at 10:54 +0800, Yijing Wang wrote:
>> We found some strange devices in HP C7000 and Huawei 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.
>> \-[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
>>
>> Signed-off-by: Yijing Wang <[email protected]>
>> ---
>> arch/x86/include/asm/iommu.h | 2 ++
>> arch/x86/kernel/pci-dma.c | 8 ++++++++
>> drivers/iommu/intel-iommu.c | 41
>> +++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 51 insertions(+), 0 deletions(-)
>>
>> 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);
>
> Documentation/kernel-parameters.txt?
>
>> + }
>>
>> gart_parse_options(p);
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index d1f5caa..49757f1 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -2705,6 +2705,47 @@ static int __init
>> iommu_prepare_static_identity_mapping(int hw)
>> return ret;
>> }
>>
>> + /* We found some strange devices in HP c7000 and other platforms that
>> + * can not be enumerated by OS, but they did DMA read/write without
>> + * driver management, so we should create the pt mapping for these
>> + * devices to avoid DMA errors. Add iommu=pt_force=segment:busnum to
>> + * force to do pt context mapping in the bus number.
>> + */
>
> So best case with this patch is that the user needs to discover that
> this option exists, figure out the undocumented parameters, be running
> on VT-d, permanently add a kernel commandline option, and never have any
> intention of assigning the device to userspace or a VM...
>
> Can't we handle this with the DMA alias quirks that are now in 3.17? Or
> can the vendor fix this with a firmware update? This device behavior is
> really quite broken for this kind of server class product.
Yeah, something doesn't sound right here.
I would like to hear more about this configuration, off list if you prefer.
What servers? What firmware revisions?
Thanks,
-- ljk
> Thanks,
>
> Alex
>
>> + 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;
>> }
>>
>
>
>
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