Can't access RAM from PCIe when using Xeon

[rshal2]

Hello,

I use Intel Xeon with centos8 , kernel 4.18.

There is also an FPGA connected to CPU through PCIe.

The FPGA try to access RAM (through DMA) using physical address in RAM, but it fails in access.

1. using older PC (Intel DUO), with same OS, FPGA, etc - accessing RAM from FPGA is successful.
2. Install windows on the same PC - accessing RAM from FPGA is successful.
3. using 
4. intel_iommu=off
5.  in the PC - does not help, same problem.

What can cause this failure ? BIOS ? If so, why changing to windows solved it and why intel_iommu=off didn't help ?

Thank you

[CarlosAM_INTEL]

Hello, @rshal2​:

Thank you for contacting Intel Embedded Community.

In order to be on the same page, could you please let us know the part number of the processor and FPGA related to this thread?

We are waiting for your clarification.

Best regards,

@Mæcenas_INTEL​.

[rshal2]

Hello,

Please see full info of /proc/cpuinfo

processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1233.239 cache size : 10240 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3599.93 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 1 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1200.047 cache size : 10240 KB physical id : 0 siblings : 4 core id : 1 cpu cores : 4 apicid : 2 initial apicid : 2 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3599.93 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 2 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1421.319 cache size : 10240 KB physical id : 0 siblings : 4 core id : 2 cpu cores : 4 apicid : 4 initial apicid : 4 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3599.93 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 3 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1398.681 cache size : 10240 KB physical id : 0 siblings : 4 core id : 3 cpu cores : 4 apicid : 6 initial apicid : 6 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3599.93 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 4 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1800.075 cache size : 10240 KB physical id : 1 siblings : 4 core id : 0 cpu cores : 4 apicid : 32 initial apicid : 32 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3606.18 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 5 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1628.205 cache size : 10240 KB physical id : 1 siblings : 4 core id : 1 cpu cores : 4 apicid : 34 initial apicid : 34 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3606.18 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 6 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1425.047 cache size : 10240 KB physical id : 1 siblings : 4 core id : 2 cpu cores : 4 apicid : 36 initial apicid : 36 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3606.18 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:   processor : 7 vendor_id : GenuineIntel cpu family : 6 model : 45 model name : Intel(R) Xeon(R) CPU E5-2603 0 @ 1.80GHz stepping : 7 microcode : 0x714 cpu MHz : 1799.752 cache size : 10240 KB physical id : 1 siblings : 4 core id : 3 cpu cores : 4 apicid : 38 initial apicid : 38 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm arat pln pts flush_l1d bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf bogomips : 3606.18 clflush size : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual power management:  

FPGA is Altera Arria 10.

Please see dmesg here:

https://docs.google.com/document/d/1EqrKC9aSFwd6MswLb1REIwhFcNQUG_uoeHmQTElj958/edit?usp=sharing

I also tried to add intel_iommu=off in kernel parameters (it did not help), so here is the dmesg in that case:

https://docs.google.com/document/d/1YPnPYCYfbjZ3ZA6XJ5ReBzIkUUgxOJ80s3PzX-gh0zk/edit?usp=sharing

Is there any workaround you can think of ? Maybe disabling iommu in BIOS ?

Thanks

[CarlosAM_INTEL]

Hello, @rshal2​:

Thanks for your reply.

The Intel® Xeon® Processor E5-2603 is a non-embedded processor as you may confirm at:

https://ark.intel.com/content/www/us/en/ark/products/64592/intel-xeon-processor-e5-2603-10m-cache-1-80-ghz-6-40-gt-s-intel-qpi.html

Due to this fact, this thread has been trasferred to the proper channel to answer your questions.

We really appreciate your patience and understanding.

Best regards,

@Mæcenas_INTEL​.

[rshal2]

Where is it moved to ???

Nowhere ???

[rshal2]

Can anyone please help with it ?

Is it a HW bug in Xoen chip ?

Regards,

Ran