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    SubjectRe: [PATCH 3/7] KVM-HV: KVM Steal time implementation
    On 06/14/2011 04:45 AM, Gleb Natapov wrote:
    > On Mon, Jun 13, 2011 at 07:31:33PM -0400, Glauber Costa wrote:
    >> 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>
    >> CC: Anthony Liguori<aliguori@us.ibm.com>
    >> CC: Eric B Munson<emunson@mgebm.net>
    >> ---
    >> arch/x86/include/asm/kvm_host.h | 8 +++++
    >> arch/x86/include/asm/kvm_para.h | 4 ++
    >> arch/x86/kvm/x86.c | 60 +++++++++++++++++++++++++++++++++++++--
    >> 3 files changed, 69 insertions(+), 3 deletions(-)
    >>
    >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    >> index fc38eca..5dce014 100644
    >> --- a/arch/x86/include/asm/kvm_host.h
    >> +++ b/arch/x86/include/asm/kvm_host.h
    >> @@ -388,6 +388,14 @@ struct kvm_vcpu_arch {
    >> unsigned int hw_tsc_khz;
    >> unsigned int time_offset;
    >> struct page *time_page;
    >> +
    >> + struct {
    >> + u64 msr_val;
    >> + gpa_t stime;
    >> + struct kvm_steal_time steal;
    >> + u64 this_time_out;
    >> + } st;
    >> +
    >> u64 last_guest_tsc;
    >> u64 last_kernel_ns;
    >> u64 last_tsc_nsec;
    >> diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
    >> index ac306c4..0341e61 100644
    >> --- a/arch/x86/include/asm/kvm_para.h
    >> +++ b/arch/x86/include/asm/kvm_para.h
    >> @@ -45,6 +45,10 @@ struct kvm_steal_time {
    >> __u32 pad[6];
    >> };
    >>
    >> +#define KVM_STEAL_ALIGNMENT_BITS 5
    >> +#define KVM_STEAL_VALID_BITS ((-1ULL<< (KVM_STEAL_ALIGNMENT_BITS + 1)))
    >> +#define KVM_STEAL_RESERVED_MASK (((1<< KVM_STEAL_ALIGNMENT_BITS) - 1 )<< 1)
    >> +
    >> #define KVM_MAX_MMU_OP_BATCH 32
    >>
    >> #define KVM_ASYNC_PF_ENABLED (1<< 0)
    >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    >> index 6645634..10fe028 100644
    >> --- a/arch/x86/kvm/x86.c
    >> +++ b/arch/x86/kvm/x86.c
    >> @@ -797,12 +797,12 @@ 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
    >> @@ -1480,6 +1480,34 @@ static void kvmclock_reset(struct kvm_vcpu *vcpu)
    >> }
    >> }
    >>
    >> +static void record_steal_time(struct kvm_vcpu *vcpu)
    >> +{
    >> + u64 delta;
    >> +
    >> + if (vcpu->arch.st.stime&& vcpu->arch.st.this_time_out) {
    >> +
    >> + if (unlikely(kvm_read_guest(vcpu->kvm, vcpu->arch.st.stime,
    >> + &vcpu->arch.st.steal, sizeof(struct kvm_steal_time)))) {
    >> +
    >> + vcpu->arch.st.stime = 0;
    >> + return;
    >> + }
    >> +
    >> + delta = (get_kernel_ns() - vcpu->arch.st.this_time_out);
    >> +
    >> + vcpu->arch.st.steal.steal += delta;
    >> + vcpu->arch.st.steal.version += 2;
    >> +
    >> + if (unlikely(kvm_write_guest(vcpu->kvm, vcpu->arch.st.stime,
    > Why not use kvm_write_guest_cached() here and introduce kvm_read_guest_cached()
    > for the read above?

    Good idea, I can do that.

    >> + &vcpu->arch.st.steal, sizeof(struct kvm_steal_time)))) {
    >> +
    >> + vcpu->arch.st.stime = 0;
    >> + return;
    >> + }
    >> + }
    >> +
    >> +}
    >> +
    >> int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
    >> {
    >> switch (msr) {
    >> @@ -1562,6 +1590,23 @@ 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:
    >> + vcpu->arch.st.msr_val = data;
    >> +
    >> + if (!(data& KVM_MSR_ENABLED)) {
    >> + vcpu->arch.st.stime = 0;
    >> + break;
    >> + }
    >> +
    >> + if (data& KVM_STEAL_RESERVED_MASK)
    >> + return 1;
    >> +
    >> + vcpu->arch.st.this_time_out = get_kernel_ns();
    >> + vcpu->arch.st.stime = data& KVM_STEAL_VALID_BITS;
    >> + record_steal_time(vcpu);
    >> +
    >> + 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:
    >> @@ -1847,6 +1892,9 @@ 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.st.msr_val;
    >> + break;
    >> case MSR_IA32_P5_MC_ADDR:
    >> case MSR_IA32_P5_MC_TYPE:
    >> case MSR_IA32_MCG_CAP:
    >> @@ -2158,6 +2206,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
    >> kvm_migrate_timers(vcpu);
    >> vcpu->cpu = cpu;
    >> }
    >> +
    >> + record_steal_time(vcpu);
    >> }
    >>
    >> void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
    >> @@ -2165,6 +2215,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
    >> kvm_x86_ops->vcpu_put(vcpu);
    >> kvm_put_guest_fpu(vcpu);
    >> kvm_get_msr(vcpu, MSR_IA32_TSC,&vcpu->arch.last_guest_tsc);
    >> + vcpu->arch.st.this_time_out = get_kernel_ns();
    >> }
    >>
    > Shouldn't we call record_steal_time(vcpu)/vcpu->arch.st.this_time_out = get_kernel_ns();
    > just before/after entering/exiting a guest? vcpu_(put|get) are called
    > for each vcpu ioctl, not only VCPU_RUN.
    >
    >> static int is_efer_nx(void)
    >> @@ -2477,7 +2528,8 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
    >> (1<< KVM_FEATURE_NOP_IO_DELAY) |
    >> (1<< KVM_FEATURE_CLOCKSOURCE2) |
    >> (1<< KVM_FEATURE_ASYNC_PF) |
    >> - (1<< KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
    >> + (1<< KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
    >> + (1<< KVM_FEATURE_STEAL_TIME);
    >> entry->ebx = 0;
    >> entry->ecx = 0;
    >> entry->edx = 0;
    >> @@ -6200,6 +6252,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
    >>
    >> kvmclock_reset(vcpu);
    >>
    >> + vcpu->arch.st.stime = 0;
    >> +
    >> kvm_clear_async_pf_completion_queue(vcpu);
    >> kvm_async_pf_hash_reset(vcpu);
    >> vcpu->arch.apf.halted = false;
    >> --
    >> 1.7.3.4
    >>
    >> --
    >> To unsubscribe from this list: send the line "unsubscribe kvm" in
    >> the body of a message to majordomo@vger.kernel.org
    >> More majordomo info at http://vger.kernel.org/majordomo-info.html
    >
    > --
    > Gleb.



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