[00/10] KVM: x86: pvclock fixes and cleanups

Message

Sean Christopherson Jan. 18, 2025, 12:55 a.m. UTC

Fix a lockdep splat in KVM's suspend notifier by simply removing a
spurious kvm->lock acquisition related to kvmclock, and then try to
wrangle KVM's pvclock handling into something approaching sanity (I
made the mistake of looking at how KVM handled PVCLOCK_GUEST_STOPPED).

David,

I didn't look too closely to see how this interacts with your overhaul of
the pvclock madness[*].  When I first started poking at this, I didn't
realize vcpu->arch.hv_lock had tendrils in so many places.  Please holler
if you want me to drop the vcpu->arch.hv_lock changes and/or tweak
something to make it play nice with your series.

The Xen changes are *very* lightly tested, so I definitely won't apply
the potentially problematic changes, i.e. anything past "Don't bleed
PVCLOCK_GUEST_STOPPED across PV clocks", until I get a thumbs up from
you and/or Paul.

[*] https://lore.kernel.org/all/[e-mail]

Sean Christopherson (10):
  KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend
    notifier
  KVM: x86: Eliminate "handling" of impossible errors during SUSPEND
  KVM: x86: Drop local pvclock_flags variable in kvm_guest_time_update()
  KVM: x86: Set PVCLOCK_GUEST_STOPPED only for kvmclock, not for Xen PV
    clock
  KVM: x86: Don't bleed PVCLOCK_GUEST_STOPPED across PV clocks
  KVM: x86/xen: Use guest's copy of pvclock when starting timer
  KVM: x86: Pass reference pvclock as a param to
    kvm_setup_guest_pvclock()
  KVM: x86: Remove per-vCPU "cache" of its reference pvclock
  KVM: x86: Setup Hyper-V TSC page before Xen PV clocks (during clock
    update)
  KVM: x86: Override TSC_STABLE flag for Xen PV clocks in
    kvm_guest_time_update()

 arch/x86/include/asm/kvm_host.h |   3 +-
 arch/x86/kvm/x86.c              | 115 ++++++++++++++++----------------
 arch/x86/kvm/xen.c              |  62 +++++++++++++++--
 3 files changed, 114 insertions(+), 66 deletions(-)


base-commit: eb723766b1030a23c38adf2348b7c3d1409d11f0