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| author | Eric B Munson <emunson@mgebm.net> | 2012-03-10 20:37:27 +0100 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2012-04-08 11:49:01 +0200 |
| commit | 1c0b28c2a46d98cd258d96b8c222144b22876c46 (patch) | |
| tree | 68c5b4f6a74e3b245dd994752fdc9005075b485c /Documentation/virtual | |
| parent | kvmclock: Add functions to check if the host has stopped the vm (diff) | |
| download | linux-1c0b28c2a46d98cd258d96b8c222144b22876c46.tar.xz linux-1c0b28c2a46d98cd258d96b8c222144b22876c46.zip | |
KVM: x86: Add ioctl for KVM_KVMCLOCK_CTRL
Now that we have a flag that will tell the guest it was suspended, create an
interface for that communication using a KVM ioctl.
Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 20 | ||||
| -rw-r--r-- | Documentation/virtual/kvm/msr.txt | 4 |
2 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 6386f8c0482e..81ff39f6248d 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1669,6 +1669,26 @@ at the memory location pointed to by "addr". The list of registers accessible using this interface is identical to the list in 4.64. +4.70 KVM_KVMCLOCK_CTRL + +Capability: KVM_CAP_KVMCLOCK_CTRL +Architectures: Any that implement pvclocks (currently x86 only) +Type: vcpu ioctl +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 +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 +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 +after pausing the vcpu, but before it is resumed. + 5. The kvm_run structure Application code obtains a pointer to the kvm_run structure by diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt index 50317809113d..96b41bd97523 100644 --- a/Documentation/virtual/kvm/msr.txt +++ b/Documentation/virtual/kvm/msr.txt @@ -109,6 +109,10 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01 0 | 24 | multiple cpus are guaranteed to | | be monotonic ------------------------------------------------------------- + | | guest vcpu has been paused by + 1 | N/A | the host + | | See 4.70 in api.txt + ------------------------------------------------------------- Availability of this MSR must be checked via bit 3 in 0x4000001 cpuid leaf prior to usage. |