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From:   Hikaru Nishida <hikalium@chromium.org>
To:     kvm@vger.kernel.org
Cc:     suleiman@google.com, Hikaru Nishida <hikalium@chromium.org>,
        Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        John Stultz <john.stultz@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [RFC PATCH 0/6] x86/kvm: Virtual suspend time injection support
Date:   Mon, 26 Apr 2021 18:06:39 +0900
Message-Id: <20210426090644.2218834-1-hikalium@chromium.org>
MIME-Version: 1.0
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Hi,

This patch series adds virtual suspend time injection support to KVM.

Before this change, if the host goes into suspended state while the
guest is running, the guest will experience a time jump after the host's
resume. This can confuse some services in the guest since they can't
detect if the system went into suspend or not by comparing
CLOCK_BOOTTIME and CLOCK_MONOTONIC.

To solve this problem, we wanted to add a way to adjust the guest clocks
without actually suspending the guests. However, there was no way to
modify a gap between CLOCK_BOOTTIME and CLOCK_MONOTONIC without actually
suspending the guests. Therefore, this series introduce a new struct
called kvm_host_suspend_time to share the suspend time between host and
guest and a mechanism to inject a suspend time to the guest while
keeping
monotonicity of the clocks.

Could you take a look and let me know how we can improve the patches if
they are doing something wrong?

Thanks,

Hikaru Nishida


Hikaru Nishida (6):
  x86/kvm: Reserve KVM_FEATURE_HOST_SUSPEND_TIME and
    MSR_KVM_HOST_SUSPEND_TIME
  x86/kvm: Add a struct and constants for virtual suspend time injection
  x86/kvm: Add CONFIG_KVM_VIRT_SUSPEND_TIMING
  x86/kvm: Add a host side support for virtual suspend time injection
  x86/kvm: Add CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST
  x86/kvm: Add a guest side support for virtual suspend time injection

 Documentation/virt/kvm/cpuid.rst     |  3 +
 Documentation/virt/kvm/msr.rst       | 29 +++++++++
 arch/x86/Kconfig                     | 13 ++++
 arch/x86/include/asm/kvm_host.h      |  5 ++
 arch/x86/include/asm/kvm_para.h      |  9 +++
 arch/x86/include/uapi/asm/kvm_para.h |  6 ++
 arch/x86/kernel/kvmclock.c           | 25 ++++++++
 arch/x86/kvm/Kconfig                 | 13 ++++
 arch/x86/kvm/cpuid.c                 |  4 ++
 arch/x86/kvm/x86.c                   | 89 +++++++++++++++++++++++++++-
 include/linux/kvm_host.h             |  7 +++
 include/linux/timekeeper_internal.h  |  4 ++
 kernel/time/timekeeping.c            | 31 ++++++++++
 13 files changed, 237 insertions(+), 1 deletion(-)

-- 
2.31.1.498.g6c1eba8ee3d-goog