From 9ddabbe72e41ca6794cb4947c70929c9410e6752 Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Mon, 11 Jul 2011 15:28:13 -0400 Subject: [PATCH] KVM: KVM Steal time guest/host interface To implement steal time, we need the hypervisor to pass the guest information about how much time was spent running other processes outside the VM. This is per-vcpu, and using the kvmclock structure for that is an abuse we decided not to make. In this patchset, I am introducing a new msr, KVM_MSR_STEAL_TIME, that holds the memory area address containing information about steal time This patch contains the headers for it. I am keeping it separate to facilitate backports to people who wants to backport the kernel part but not the hypervisor, or the other way around. Signed-off-by: Glauber Costa Acked-by: Rik van Riel Tested-by: Eric B Munson CC: Jeremy Fitzhardinge CC: Peter Zijlstra CC: Anthony Liguori Signed-off-by: Avi Kivity --- Documentation/virtual/kvm/msr.txt | 34 +++++++++++++++++++++++++++++++ arch/x86/include/asm/kvm_para.h | 9 ++++++++ 2 files changed, 43 insertions(+) diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt index d079aed27e03..50317809113d 100644 --- a/Documentation/virtual/kvm/msr.txt +++ b/Documentation/virtual/kvm/msr.txt @@ -185,3 +185,37 @@ MSR_KVM_ASYNC_PF_EN: 0x4b564d02 Currently type 2 APF will be always delivered on the same vcpu as type 1 was, but guest should not rely on that. + +MSR_KVM_STEAL_TIME: 0x4b564d03 + + data: 64-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_steal_time { + __u64 steal; + __u32 version; + __u32 flags; + __u32 pad[12]; + } + + whose data will be filled in by the hypervisor periodically. Only one + write, or registration, is needed for each VCPU. The interval between + updates of this structure is arbitrary and implementation-dependent. + The hypervisor may update this structure at any time it sees fit until + anything with bit0 == 0 is written to it. Guest is required to make sure + this structure is initialized to zero. + + Fields have the following meanings: + + version: a sequence counter. In other words, guest has to check + this field before and after grabbing time information and make + sure they are both equal and even. An odd version indicates an + in-progress update. + + flags: At this point, always zero. May be used to indicate + changes in this structure in the future. + + steal: the amount of time in which this vCPU did not run, in + nanoseconds. Time during which the vcpu is idle, will not be + reported as steal time. diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index d6cd79b34aab..65f8bb9279e0 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -21,6 +21,7 @@ */ #define KVM_FEATURE_CLOCKSOURCE2 3 #define KVM_FEATURE_ASYNC_PF 4 +#define KVM_FEATURE_STEAL_TIME 5 /* The last 8 bits are used to indicate how to interpret the flags field * in pvclock structure. If no bits are set, all flags are ignored. @@ -35,6 +36,14 @@ #define MSR_KVM_WALL_CLOCK_NEW 0x4b564d00 #define MSR_KVM_SYSTEM_TIME_NEW 0x4b564d01 #define MSR_KVM_ASYNC_PF_EN 0x4b564d02 +#define MSR_KVM_STEAL_TIME 0x4b564d03 + +struct kvm_steal_time { + __u64 steal; + __u32 version; + __u32 flags; + __u32 pad[12]; +}; #define KVM_MAX_MMU_OP_BATCH 32