linux-kernel - [PATCH v3 0/2] KVM: x86: hyper-v: Fix TSC page update after KVM_SET

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Date:   Wed, 31 Mar 2021 14:41:28 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/2] KVM: x86: hyper-v: Fix TSC page update after KVM_SET_CLOCK(0) call

Changes since v2:
- Fix the issue by using master_kernel_ns/get_kvmclock_base_ns() instead of
 get_kvmclock_ns() when handling KVM_SET_CLOCK.
- Rebase on Paolo's "KVM: x86: fix lockdep splat due to Xen runstate
 update" series and use spin_lock_irq()/spin_unlock_irq() [Paolo]

Original description:

I discovered that after KVM_SET_CLOCK(0) TSC page value in the guest can
go through the roof and apparently we have a signedness issue when the
update is performed. Fix the issue and add a selftest.

Vitaly Kuznetsov (2):
  KVM: x86: Prevent 'hv_clock->system_time' from going negative in
    kvm_guest_time_update()
  selftests: kvm: Check that TSC page value is small after
    KVM_SET_CLOCK(0)

 arch/x86/kvm/x86.c                            | 19 +++++++++++++++++--
 .../selftests/kvm/x86_64/hyperv_clock.c       | 13 +++++++++++--
 2 files changed, 28 insertions(+), 4 deletions(-)

-- 
2.30.2