Cache topology under virtual guests

[dd86k]

Cache detected is affected when running under a virtual guest.

Even cpufetch is affected (i7-3770):

L1i Size:   32KB (64KB Total)
L1d Size:   32KB (64KB Total)
L2 Size:    256KB (512KB Total)
L3 Size:    8MB (16MB Total)

0.18.1:

L1-D: 2x   32 KiB
L1-I: 2x   32 KiB
L2-U: 2x  256 KiB
L3-U: 2x    8 MiB

0.19-master:

Cache L1-D:  2x 32KB    (64KB)
Cache L1-I:  2x 32KB    (64KB)
Cache L2-U:  2x 256KB   (512KB)
Cache L3-U:  2x 8MB     (16MB)

Now I haven't really checked if this is due to the Hyper-V paravirtualization in VirtualBox but this seems to be appearing frequently. I will have to do another post with different virtual platforms (e.g., VMware, VirtualBox, KVM, QEMU, etc.) and paravirtualization platforms.

[dd86k]

Version: 0.19

Under KVM (OVH): (supposed to have 4 cores)

Name:        GenuineIntel Intel Core Processor (Haswell, no TSX)
Identifier:  Family 0x6 Model 0x3c Stepping 0x1
Cores:       1 cores 1 threads
Max. Memory: 1TB physical 256TB virtual
Techs:       x86-64-v3
SSE:         SSE SSE2 SSE3 SSSE3 SSE4.2
AVX:         AVX AVX2
AMX:         None
Others:      AES-NI BMI1 BMI2
Mitigations: MD_CLEAR
ParaVirt.:   KVM
Cache L1-D:  1x 32KB    (32KB)   SI NWBV
Cache L1-I:  1x 32KB    (32KB)   SI NWBV
Cache L2-U:  1x 4MB     (4MB)    SI NWBV
Cache L3-U:  1x 16MB    (16MB)   SI CI CCI

Table

With relevant data

| Leaf     | Sub-leaf | EAX      | EBX      | ECX      | EDX      |
|----------|----------|----------|----------|----------|----------|
|        4 |        0 |      121 |  1c0003f |       3f |        1 |
|        4 |        1 |      122 |  1c0003f |       3f |        1 |
|        4 |        2 |      143 |  3c0003f |      fff |        1 |
|        4 |        3 |      163 |  3c0003f |     3fff |        6 |
|        4 |        4 |        0 |        0 |        0 |        0 |
|        b |        0 |        0 |        1 |      100 |        2 |
|        b |        1 |        0 |        1 |      201 |        2 |
|        b |        2 |        0 |        0 |        2 |        2 |

[dd86k]

e.g.,

• adjusting core count and not showing "0 cores, 1 thread".
• Only Intel calculations have this issue. AMD seems.. fine

[dd86k]

Related to #43 and cache topo modified by vmm is probably normal anyway