[PATCH v2 0/4] x86/kvm/hyper-v: More fixes for TSC page clocksource for Hyper-V on KVM

Vitaly Kuznetsov
2018-03-01T14:15:21Z

Changes since v1:
- Drop 'polling' bit check for now as we don't support this mode
[Roman Kagan].
- Add a comment explaining "!host && !masked" in synic_set_sint()
- Add Roman's R-b to PATCH1 and PATCH2.

Previously (see commit 72c139bacf) it was found that Hyper-V frequency
MSRs are required to make Hyper-V on KVM pass through TSC page as stable
clocksource to its guests. However, to make things work this is not
enough. Hyper-V tries to prove that TSC frequency underneath it won't
change (e.g. when it's migrated), there are two mechanisms:

1) Invariant TSC (CPUID.80000007H:EDX[8]). If Hyper-V sees this bit it will
treat TSC as stable. We, however, don't want to pass it as it makes
migration hard (e.g. Qemu adds a migration blocker when 'invtsc' flag is
passed. Genuine Hyper-V running in L0 doesn't pass it either.

2) Hyper-V Reenlightenment (CPUID.40000003H:EAX[13]).

This patch series add rudimentary support for Hyper-V reenlightenment
notifications to KVM ('producer' part; we already implemented
reenlightenment 'consumer' for KVM-on Hyper-V some time ago) and fixes
bugs I found during testing. Fully fledged reenlightenment implementation
will be added later when we learn to migrate nested workloads in KVM making
testing possible.

Qemu patches are also required, I'll post them separately.

Vitaly Kuznetsov (3):
x86/kvm/hyper-v: add reenlightenment MSRs support
x86/kvm/hyper-v: remove stale entries from vec_bitmap/auto_eoi_bitmap
on vector change
x86/kvm/hyper-v: inject #GP only when invalid SINTx vector is unmasked

arch/x86/include/asm/kvm_host.h | 4 +++
arch/x86/include/uapi/asm/hyperv.h | 2 ++
arch/x86/kvm/hyperv.c | 61 +++++++++++++++++++++++++++++++-------
arch/x86/kvm/x86.c | 12 +++++++-
4 files changed, 68 insertions(+), 11 deletions(-)

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