qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
* [Bug 1902451] [NEW] incorrect cpuid feature detection
@ 2020-11-01 20:43 Luis
  2020-11-01 20:57 ` [Bug 1902451] " Luis
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Luis @ 2020-11-01 20:43 UTC (permalink / raw)
  To: qemu-devel

Public bug reported:

Hello,

I am currently developing a x64 kernel and I wanted to check through
cpuid if some features are available in the guest. When I try to enable
cpu features like vmcb_clean or constant_tsc qemu is saying that my host
doesn't support the requested features. However cat /proc/cpuinfo tells
a different story:

model name:  AMD Ryzen 5 3500U
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate sme pti ssbd sev ibpb vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 xsaves clzero irperf xsaveerptr arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov succor smca

I also checked it myself by running cpuid and check the bits as in the
AMD Manual. Everything checks out but qemu still fails.

QEMU version: QEMU emulator version 4.2.0

$ qemu-system-x86_64 -cpu host,+vmcb_clean,enforce -enable-kvm -drive format=raw,file=target/x86_64-os/debug/bootimage-my_kernel.bin -serial stdio -display none
qemu-system-x86_64: warning: host doesn't support requested feature: CPUID.8000000AH:EDX.vmcb-clean [bit 5]
qemu-system-x86_64: Host doesn't support requested features

or

$ qemu-system-x86_64 -cpu host,+constant_tsc,enforce -enable-kvm -drive format=raw,file=target/x86_64-os/debug/bootimage-my_kernel.bin -serial stdio -display none
qemu-system-x86_64: Property '.constant_tsc' not found

** Affects: qemu
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1902451

Title:
  incorrect cpuid feature detection

Status in QEMU:
  New

Bug description:
  Hello,

  I am currently developing a x64 kernel and I wanted to check through
  cpuid if some features are available in the guest. When I try to
  enable cpu features like vmcb_clean or constant_tsc qemu is saying
  that my host doesn't support the requested features. However cat
  /proc/cpuinfo tells a different story:

  model name:  AMD Ryzen 5 3500U
  flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate sme pti ssbd sev ibpb vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 xsaves clzero irperf xsaveerptr arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov succor smca

  I also checked it myself by running cpuid and check the bits as in the
  AMD Manual. Everything checks out but qemu still fails.

  QEMU version: QEMU emulator version 4.2.0

  $ qemu-system-x86_64 -cpu host,+vmcb_clean,enforce -enable-kvm -drive format=raw,file=target/x86_64-os/debug/bootimage-my_kernel.bin -serial stdio -display none
  qemu-system-x86_64: warning: host doesn't support requested feature: CPUID.8000000AH:EDX.vmcb-clean [bit 5]
  qemu-system-x86_64: Host doesn't support requested features

  or

  $ qemu-system-x86_64 -cpu host,+constant_tsc,enforce -enable-kvm -drive format=raw,file=target/x86_64-os/debug/bootimage-my_kernel.bin -serial stdio -display none
  qemu-system-x86_64: Property '.constant_tsc' not found

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1902451/+subscriptions


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-07-09  4:30 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-01 20:43 [Bug 1902451] [NEW] incorrect cpuid feature detection Luis
2020-11-01 20:57 ` [Bug 1902451] " Luis
2021-05-09 14:56 ` Thomas Huth
2021-07-09  4:17 ` Launchpad Bug Tracker

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).