[PATCH v3 2/6] KVM-HV: KVM Steal time implementation

Glauber Costa
2011-02-11T18:19:20Z

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 hypervisor part for it. I am keeping it separate from
the headers 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 <glommer@redhat.com>
CC: Rik van Riel <riel@redhat.com>
CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Avi Kivity <avi@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 5 +++++
arch/x86/kvm/x86.c | 39 +++++++++++++++++++++++++++++++++++++--
2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ffd7f8d..be6e0e2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -377,6 +377,11 @@ struct kvm_vcpu_arch {
unsigned int hw_tsc_khz;
unsigned int time_offset;
struct page *time_page;
+
+ gpa_t stime;
+ struct kvm_steal_time steal;
+ u64 this_time_out;
+
u64 last_host_tsc;
u64 last_guest_tsc;
u64 last_kernel_ns;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7a326cb..7f14900 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -787,12 +787,12 @@ EXPORT_SYMBOL_GPL(kvm_get_dr);
* kvm-specific. Those are put in the beginning of the list.
*/

-#define KVM_SAVE_MSRS_BEGIN 8
+#define KVM_SAVE_MSRS_BEGIN 9
static u32 msrs_to_save[] = {
MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
MSR_KVM_SYSTEM_TIME_NEW, MSR_KVM_WALL_CLOCK_NEW,
HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
- HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN,
+ HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
MSR_STAR,
#ifdef CONFIG_X86_64
@@ -1546,6 +1546,16 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
if (kvm_pv_enable_async_pf(vcpu, data))
return 1;
break;
+ case MSR_KVM_STEAL_TIME:
+
+ if (!(data & 1)) {
+ vcpu->arch.stime = 0;
+ break;
+ }
+
+ vcpu->arch.stime = data & ~1;
+ break;
+
case MSR_IA32_MCG_CTL:
case MSR_IA32_MCG_STATUS:
case MSR_IA32_MC0_CTL ... MSR_IA32_MC0_CTL + 4 * KVM_MAX_MCE_BANKS - 1:
@@ -1831,6 +1841,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
case MSR_KVM_ASYNC_PF_EN:
data = vcpu->arch.apf.msr_val;
break;
+ case MSR_KVM_STEAL_TIME:
+ data = vcpu->arch.stime;
+ break;
case MSR_IA32_P5_MC_ADDR:
case MSR_IA32_P5_MC_TYPE:
case MSR_IA32_MCG_CAP:
@@ -1993,6 +2006,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_X86_ROBUST_SINGLESTEP:
case KVM_CAP_XSAVE:
case KVM_CAP_ASYNC_PF:
+ case KVM_CAP_STEAL_TIME:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -2108,6 +2122,9 @@ static bool need_emulate_wbinvd(struct kvm_vcpu *vcpu)

void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
+ struct kvm_steal_time *st;
+ st = (struct kvm_steal_time *)vcpu->arch.stime;
+
/* Address WBINVD may be executed by guest */
if (need_emulate_wbinvd(vcpu)) {
if (kvm_x86_ops->has_wbinvd_exit())
@@ -2133,6 +2150,21 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
kvm_migrate_timers(vcpu);
vcpu->cpu = cpu;
}
+
+ if (vcpu->arch.this_time_out) {
+ u64 to = (get_kernel_ns() - vcpu->arch.this_time_out);
+
+ kvm_read_guest(vcpu->kvm, (gpa_t)st, &vcpu->arch.steal,
+ sizeof(*st));
+
+ vcpu->arch.steal.steal += to;
+ vcpu->arch.steal.version += 2;
+
+ kvm_write_guest(vcpu->kvm, (gpa_t)st, &vcpu->arch.steal,
+ sizeof(*st));
+ /* is it possible to have 2 loads in sequence? */
+ vcpu->arch.this_time_out = 0;
+ }
}

void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
@@ -2140,6 +2172,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
kvm_x86_ops->vcpu_put(vcpu);
kvm_put_guest_fpu(vcpu);
vcpu->arch.last_host_tsc = native_read_tsc();
+ vcpu->arch.this_time_out = get_kernel_ns();
}

static int is_efer_nx(void)
@@ -5882,6 +5915,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)

kvmclock_reset(vcpu);

+ vcpu->arch.stime = 0;
+
kvm_clear_async_pf_completion_queue(vcpu);
kvm_async_pf_hash_reset(vcpu);
vcpu->arch.apf.halted = false;
--
1.7.2.3