id = 742
title = "Cache Layout wrong on many Zen Arch CPUs"
state = "opened"
created_at = "2021-11-22T09:35:16.250Z"
closed_at = "n/a"
labels = ["accel: KVM", "target: i386"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/742"
host-os = "Arch Linux"
host-arch = "x86_64"
qemu-version = "6.1.0"
guest-os = "Windows 10 Pro"
guest-arch = "x86"
description = """This is `coreinfo -l` when running Windows as host:

![image](/uploads/b4217fd80071c95e20e7d729e0fd19fa/image.png)

This is `coreinfo -l` when running the same Windows as guest with 6 cores and 6 threads (half of each):

![image](/uploads/bb6f2ccbec661273e83e36d3e1bff309/image.png)"""
reproduce = """1. You need a AMD Ryzen 3900X. It has an L3 cache over 3 cores
2. Use `-cpu host,+topoext,host-cache-info=on`
3. Use `coreinfo -l` to see how the L3 cache is distributed"""
additional = """1. When running without `host-cache-info=on` then the L3 cache is spread on all the cpus.
2. `lscpu -e`:

```
CPU NODE SOCKET CORE L1d:L1i:L2:L3 ONLINE    MAXMHZ    MINMHZ      MHZ
  0    0      0    0 0:0:0:0          yes 4672.0698 2200.0000 3800.000
  1    0      0    1 1:1:1:0          yes 4672.0698 2200.0000 3800.000
  2    0      0    2 2:2:2:0          yes 4672.0698 2200.0000 3800.000
  3    0      0    3 4:4:4:1          yes 4672.0698 2200.0000 3800.000
  4    0      0    4 5:5:5:1          yes 4672.0698 2200.0000 3800.000
  5    0      0    5 6:6:6:1          yes 4672.0698 2200.0000 3800.000
  6    0      0    6 8:8:8:2          yes 4672.0698 2200.0000 3800.000
  7    0      0    7 9:9:9:2          yes 4672.0698 2200.0000 3610.580
  8    0      0    8 10:10:10:2       yes 4672.0698 2200.0000 3800.000
  9    0      0    9 12:12:12:3       yes 4672.0698 2200.0000 3800.000
 10    0      0   10 13:13:13:3       yes 4672.0698 2200.0000 3800.000
 11    0      0   11 14:14:14:3       yes 4672.0698 2200.0000 3800.000
 12    0      0    0 0:0:0:0          yes 4672.0698 2200.0000 3800.000
 13    0      0    1 1:1:1:0          yes 4672.0698 2200.0000 3800.000
 14    0      0    2 2:2:2:0          yes 4672.0698 2200.0000 3800.000
 15    0      0    3 4:4:4:1          yes 4672.0698 2200.0000 3800.000
 16    0      0    4 5:5:5:1          yes 4672.0698 2200.0000 3800.000
 17    0      0    5 6:6:6:1          yes 4672.0698 2200.0000 3800.000
 18    0      0    6 8:8:8:2          yes 4672.0698 2200.0000 3800.000
 19    0      0    7 9:9:9:2          yes 4672.0698 2200.0000 3800.000
 20    0      0    8 10:10:10:2       yes 4672.0698 2200.0000 3800.000
 21    0      0    9 12:12:12:3       yes 4672.0698 2200.0000 3800.000
 22    0      0   10 13:13:13:3       yes 4672.0698 2200.0000 3800.000
 23    0      0   11 14:14:14:3       yes 4672.0698 2200.0000 3800.000
```"""