Please support AVX512 CPU features in guests

[hoss2608]

I have invested in a shiny new i7 7820X CPU and have installed Windows 10 on it for ease of integration with other computers..

I much prefer Linux for coding and am using VirtualBox for that.

Was surprised to find the guest OS would fault on my attempts to run AVX512 programs, but found the VBox.log entries for CPUID as follows

Code: Select all

00:00:03.679185 Structured Extended Feature Flags Enumeration (leaf 7):
00:00:03.679185   Mnemonic - Description                                  = guest (host)
00:00:03.679186   FSGSBASE - RDFSBASE/RDGSBASE/WRFSBASE/WRGSBASE instr.   = 0 (1)
00:00:03.679186   TSCADJUST - Supports MSR_IA32_TSC_ADJUST                = 0 (1)
00:00:03.679187   SGX - Supports Software Guard Extensions                = 0 (0)
00:00:03.679187   BMI1 - Advanced Bit Manipulation extension 1            = 0 (1)
00:00:03.679188   HLE - Hardware Lock Elision                             = 0 (1)
00:00:03.679189   AVX2 - Advanced Vector Extensions 2                     = 1 (1)
00:00:03.679189   FDP_EXCPTN_ONLY - FPU DP only updated on exceptions     = 1 (1)
00:00:03.679190   SMEP - Supervisor Mode Execution Prevention             = 0 (1)
00:00:03.679191   BMI2 - Advanced Bit Manipulation extension 2            = 0 (1)
00:00:03.679191   ERMS - Enhanced REP MOVSB/STOSB instructions            = 0 (1)
00:00:03.679192   INVPCID - INVPCID instruction                           = 0 (1)
00:00:03.679193   RTM - Restricted Transactional Memory                   = 0 (1)
00:00:03.679193   PQM - Platform Quality of Service Monitoring            = 0 (1)
00:00:03.679194   DEPFPU_CS_DS - Deprecates FPU CS, FPU DS values if set  = 1 (1)
00:00:03.679194   MPE - Intel Memory Protection Extensions                = 0 (1)
00:00:03.679195   PQE - Platform Quality of Service Enforcement           = 0 (1)
00:00:03.679196   AVX512F - AVX512 Foundation instructions                = 0 (1)
00:00:03.679196   17 - Reserved                                           = 0 (1)
00:00:03.679197   RDSEED - RDSEED instruction                             = 1 (1)
00:00:03.679198   ADX - ADCX/ADOX instructions                            = 0 (1)
00:00:03.679198   SMAP - Supervisor Mode Access Prevention                = 0 (1)
00:00:03.679199   CLFLUSHOPT - CLFLUSHOPT (Cache Line Flush) instruction  = 1 (1)
00:00:03.679200   24 - Reserved                                           = 0 (1)
00:00:03.679200   INTEL_PT - Intel Processor Trace                        = 0 (1)
00:00:03.679201   AVX512PF - AVX512 Prefetch instructions                 = 0 (0)
00:00:03.679202   AVX512ER - AVX512 Exponential & Reciprocal instructions = 0 (0)
00:00:03.679202   AVX512CD - AVX512 Conflict Detection instructions       = 0 (1)
00:00:03.679203   SHA - Secure Hash Algorithm extensions                  = 0 (0)
00:00:03.679203   30 - Reserved                                           = 0 (1)
00:00:03.679204   31 - Reserved                                           = 0 (1)
00:00:03.679205   PREFETCHWT1 - PREFETCHWT1 instruction                   = 0 (0)
00:00:03.679206   PKU - Protection Key for Usermode pages                 = 0 (0)
00:00:03.679206   OSPKU - CR4.PKU mirror                                  = 0 (0)

When are you going to support AVX512* on the guest ?

Thanks

Phil.

[socratis]

Partial logs are not that helpful I'm afraid. Please ZIP and attach the full log. See the "Upload attachment" tab below the reply form.

[mpack]

When are you going to support AVX512* on the guest ?

Who is this "you" being addressed? This is a user to user site, we have no more idea of the dev's plans than you do. From past experience I can only tell you that when paying customers start kicking off about a missing feature, that's when it's most likely to be implemented.

[mpack]

Partial logs are not that helpful I'm afraid. Please ZIP and attach the full log. See the "Upload attachment" tab below the reply form.

Unless things have changed, he's not allowed to attach anything in the "Suggestions" forum.

[socratis]

True, very true mpack! Thanks for that!

In that case @'hoss2608', please open your log and search for "CPUM: Matched host CPU". Post that line. Something tells me that you're going to have a Pentium in there.

I woulnd't want to move the topic from the "Suggestions" section. Not yet at least...

[hoss2608]

Thank for your replies.

From the log I find :

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00:00:03.255727 CPUM: Matched host CPU INTEL 0x6/0x55/0x4 Intel_Core7_Skylake with CPU DB entry 'Intel Core i7-6700K' (INTEL 0x6/0x5e/0x3 Intel_Core7_Skylake)

My CPU is Core i7-7820X...

[socratis]

OK, not a Pentium, but not your actual CPU either. That means that VirtualBox doesn't have the CPU in its database yet and it get the closest matching one. For example I have a Core i7-4870HQ and it comes up as a Core i7-5600U in the logs, but as the correct one in the guest. Some of the flags although do not get through, only the name.

So, I guess you'll have to wait until the VirtualBox customers ask for it, as mpack said, or the developers implement it, or you contribute the appropriate changes yourself.

[rainysun]

AVX-512 has been on consumer CPUs for six years now, is on ~10% of consumer CPUs (according to Steam hardware survey), and its successor (AVX10) has already been announced.
I presume there's still no interest in adding it to VirtualBox?

[mpack]

Locking this obsolete topic.

I believe VirtualBox added this feature long ago. However if you have Hyper-v enabled on your Windows host then Hyper-v owns such features and VirtualBox therefore can't pass them to a VM.