[RESEND,v3,0/3] i386: Fix Hyper-V Gen1 guests stuck on boot with 'hv-passthrough'

Message

Vitaly Kuznetsov March 5, 2024, 4:42 p.m. UTC

Changes since 'RESEND v2':
- Included 'docs/system: Add recommendations to Hyper-V enlightenments doc'
  in the set as it also requires a "RESEND")

Hyper-V Gen1 guests are getting stuck on boot when 'hv-passthrough' is
used. While 'hv-passthrough' is a debug only feature, this significantly
limit its usefullness. While debugging the problem, I found that there are
two loosely connected issues:
- 'hv-passthrough' enables 'hv-syndbg' and this is undesired.
- 'hv-syndbg's support by KVM is detected incorrectly when !CONFIG_SYNDBG.

Fix both issues; exclude 'hv-syndbg' from 'hv-passthrough' and don't allow
to turn on 'hv-syndbg' for !CONFIG_SYNDBG builds. 

Vitaly Kuznetsov (3):
  i386: Fix conditional CONFIG_SYNDBG enablement
  i386: Exclude 'hv-syndbg' from 'hv-passthrough'
  docs/system: Add recommendations to Hyper-V enlightenments doc

 docs/system/i386/hyperv.rst | 43 +++++++++++++++++++++++++++++++++----
 target/i386/cpu.c           |  2 ++
 target/i386/kvm/kvm.c       | 18 ++++++++++------
 3 files changed, 53 insertions(+), 10 deletions(-)

Comments

Vitaly Kuznetsov March 25, 2024, 9:28 a.m. UTC | #1

Vitaly Kuznetsov <[e-mail]> writes:

> Changes since 'RESEND v2':
> - Included 'docs/system: Add recommendations to Hyper-V enlightenments doc'
>   in the set as it also requires a "RESEND")

Ping)

>
> Hyper-V Gen1 guests are getting stuck on boot when 'hv-passthrough' is
> used. While 'hv-passthrough' is a debug only feature, this significantly
> limit its usefullness. While debugging the problem, I found that there are
> two loosely connected issues:
> - 'hv-passthrough' enables 'hv-syndbg' and this is undesired.
> - 'hv-syndbg's support by KVM is detected incorrectly when !CONFIG_SYNDBG.
>
> Fix both issues; exclude 'hv-syndbg' from 'hv-passthrough' and don't allow
> to turn on 'hv-syndbg' for !CONFIG_SYNDBG builds. 
>
> Vitaly Kuznetsov (3):
>   i386: Fix conditional CONFIG_SYNDBG enablement
>   i386: Exclude 'hv-syndbg' from 'hv-passthrough'
>   docs/system: Add recommendations to Hyper-V enlightenments doc
>
>  docs/system/i386/hyperv.rst | 43 +++++++++++++++++++++++++++++++++----
>  target/i386/cpu.c           |  2 ++
>  target/i386/kvm/kvm.c       | 18 ++++++++++------
>  3 files changed, 53 insertions(+), 10 deletions(-)