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| author | Joshua Abraham <j.abraham1776@gmail.com> | 2020-05-01 18:36:24 -0400 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2020-05-05 09:40:54 -0600 |
| commit | 35c59990058351a1c9efab9e49dd19c2e5579cfb (patch) | |
| tree | 58b192fbc7c92bf77247b751e7b7599355736346 /Documentation/virt | |
| parent | 094d6dc56245d0c796af9ed3e680effbe66ba0b5 (diff) | |
| download | linux-35c59990058351a1c9efab9e49dd19c2e5579cfb.tar.bz2 | |
docs: kvm: Fix KVM_KVMCLOCK_CTRL API doc
The KVM_KVMCLOCK_CTRL ioctl signals to supported KVM guests
that the hypervisor has paused it. Update the documentation to
reflect that the guest is notified by this API.
Signed-off-by: Joshua Abraham <sinisterpatrician@gmail.com>
Link: https://lore.kernel.org/r/20200501223624.GA25826@josh-ZenBook
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/virt')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index efbbe570aa9b..d2c1cbce1018 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -2572,13 +2572,15 @@ list in 4.68. :Parameters: None :Returns: 0 on success, -1 on error -This signals to the host kernel that the specified guest is being paused by -userspace. The host will set a flag in the pvclock structure that is checked -from the soft lockup watchdog. The flag is part of the pvclock structure that -is shared between guest and host, specifically the second bit of the flags +This ioctl sets a flag accessible to the guest indicating that the specified +vCPU has been paused by the host userspace. + +The host will set a flag in the pvclock structure that is checked from the +soft lockup watchdog. The flag is part of the pvclock structure that is +shared between guest and host, specifically the second bit of the flags field of the pvclock_vcpu_time_info structure. It will be set exclusively by the host and read/cleared exclusively by the guest. The guest operation of -checking and clearing the flag must an atomic operation so +checking and clearing the flag must be an atomic operation so load-link/store-conditional, or equivalent must be used. There are two cases where the guest will clear the flag: when the soft lockup watchdog timer resets itself or when a soft lockup is detected. This ioctl can be called any time |