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 <[email protected]> CC: Rik van Riel <[email protected]> CC: Jeremy Fitzhardinge <[email protected]> CC: Peter Zijlstra <[email protected]> CC: Avi Kivity <[email protected]> --- arch/x86/include/asm/kvm_host.h | 6 +++++ arch/x86/kvm/x86.c | 48 ++++++++++++++++++++++++++++++++++----- include/linux/kvm.h | 1 + 3 files changed, 49 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index ffd7f8d..675f7ae 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -377,6 +377,12 @@ struct kvm_vcpu_arch { unsigned int hw_tsc_khz; unsigned int time_offset; struct page *time_page; + + gpa_t stime; + u32 sversion; + u64 time_out; + 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 38b55b3..0f8a529 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 @@ -1528,16 +1528,23 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) vcpu->arch.time_page = gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); - if (is_error_page(vcpu->arch.time_page)) { - kvm_release_page_clean(vcpu->arch.time_page); - vcpu->arch.time_page = NULL; - } break; } case MSR_KVM_ASYNC_PF_EN: 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; + vcpu->arch.sversion = 0; + 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: @@ -1817,6 +1824,9 @@ 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: @@ -1966,6 +1976,7 @@ 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: @@ -2081,6 +2092,9 @@ 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()) @@ -2106,6 +2120,25 @@ 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); + /* + * using nanoseconds introduces noise, which accumulates easily + * leading to big steal time values. We want, however, to keep the + * interface nanosecond-based for future-proofness. + */ + to /= NSEC_PER_USEC; + to *= NSEC_PER_USEC; + vcpu->arch.time_out += to; + kvm_write_guest(vcpu->kvm, (gpa_t)&st->steal, + &vcpu->arch.time_out, sizeof(st->steal)); + vcpu->arch.sversion += 2; + kvm_write_guest(vcpu->kvm, (gpa_t)&st->version, + &vcpu->arch.sversion, sizeof(st->version)); + /* is it possible to have 2 loads in sequence? */ + vcpu->arch.this_time_out = 0; + } } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) @@ -2113,6 +2146,7 @@ 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) @@ -5878,6 +5912,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu) kvm_make_request(KVM_REQ_EVENT, vcpu); vcpu->arch.apf.msr_val = 0; + vcpu->arch.stime = 0; + if (vcpu->arch.time_page) { kvm_release_page_dirty(vcpu->arch.time_page); vcpu->arch.time_page = NULL; diff --git a/include/linux/kvm.h b/include/linux/kvm.h index ea2dc1a..1009060 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -541,6 +541,7 @@ struct kvm_ppc_pvinfo { #define KVM_CAP_PPC_GET_PVINFO 57 #define KVM_CAP_PPC_IRQ_LEVEL 58 #define KVM_CAP_ASYNC_PF 59 +#define KVM_CAP_STEAL_TIME 60 #ifdef KVM_CAP_IRQ_ROUTING -- 1.7.2.3 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
