No functional change; just add documentation for
KVM_FEATURE_HOST_SUSPEND_TIME and its corresponding
MSR_KVM_HOST_SUSPEND_TIME to support virtual suspend timing injection in
later patches.
Signed-off-by: Hikaru Nishida <hikalium@xxxxxxxxxxxx>
---
Documentation/virt/kvm/cpuid.rst | 3 +++
Documentation/virt/kvm/msr.rst | 30 ++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/Documentation/virt/kvm/cpuid.rst b/Documentation/virt/kvm/cpuid.rst
index bda3e3e737d7..f17b95b0d943 100644
--- a/Documentation/virt/kvm/cpuid.rst
+++ b/Documentation/virt/kvm/cpuid.rst
@@ -103,6 +103,9 @@ KVM_FEATURE_HC_MAP_GPA_RANGE 16 guest checks this feature bit bef
KVM_FEATURE_MIGRATION_CONTROL 17 guest checks this feature bit before
using MSR_KVM_MIGRATION_CONTROL
+KVM_FEATURE_HOST_SUSPEND_TIME 18 host suspend time information
+ is available at msr 0x4b564d09.
+
KVM_FEATURE_CLOCKSOURCE_STABLE_BIT 24 host will warn if no guest-side
per-cpu warps are expected in
kvmclock
diff --git a/Documentation/virt/kvm/msr.rst b/Documentation/virt/kvm/msr.rst
index 9315fc385fb0..a218a350d0d0 100644
--- a/Documentation/virt/kvm/msr.rst
+++ b/Documentation/virt/kvm/msr.rst
@@ -389,3 +389,33 @@ data:
guest is communicating page encryption status to the host using the
``KVM_HC_MAP_GPA_RANGE`` hypercall, it can set bit 0 in this MSR to
allow live migration of the guest.
+
+MSR_KVM_HOST_SUSPEND_TIME:
+ 0x4b564d09
+
+data:
+ 8-byte alignment physical address of a memory area which must be
+ in guest RAM, plus an enable bit in bit 0. This memory is expected to
+ hold a copy of the following structure::
+
+ struct kvm_suspend_time {
+ __u64 suspend_time_ns;
+ };
+
+ whose data will be filled in by the hypervisor.
+ If the guest register this structure through the MSR write, the host
+ will stop all the clocks including TSCs observed by the guest during
+ the host's suspension and report the duration of suspend through this
+ structure. The update will be notified through
+ VIRT_SUSPEND_TIMING_VECTOR IRQ. Fields have the following meanings:
+
+ suspend_time_ns:
+ Total number of nanoseconds passed during the host's suspend
+ while the VM is running. This value will be increasing
+ monotonically.
+
+ Note that although MSRs are per-CPU entities, the effect of this
+ particular MSR is global.
+
+ Availability of this MSR must be checked via bit 18 in 0x4000001 cpuid
+ leaf prior to usage.
--
2.32.0.605.g8dce9f2422-goog
