Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754388Ab1FOJKK (ORCPT ); Wed, 15 Jun 2011 05:10:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30725 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753408Ab1FOJKE (ORCPT ); Wed, 15 Jun 2011 05:10:04 -0400 Date: Wed, 15 Jun 2011 12:09:51 +0300 From: Gleb Natapov To: Glauber Costa Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Rik van Riel , Jeremy Fitzhardinge , Peter Zijlstra , Avi Kivity , Anthony Liguori , Eric B Munson Subject: Re: [PATCH 3/7] KVM-HV: KVM Steal time implementation Message-ID: <20110615090951.GQ491@redhat.com> References: <1308007897-17013-1-git-send-email-glommer@redhat.com> <1308007897-17013-4-git-send-email-glommer@redhat.com> <20110614074500.GM491@redhat.com> <4DF8226B.20408@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DF8226B.20408@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8566 Lines: 237 On Wed, Jun 15, 2011 at 12:09:31AM -0300, Glauber Costa wrote: > 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 > >>CC: Rik van Riel > >>CC: Jeremy Fitzhardinge > >>CC: Peter Zijlstra > >>CC: Avi Kivity > >>CC: Anthony Liguori > >>CC: Eric B Munson > >>--- > >> 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? > > Actually, I'd expect most read/writes to benefit from caching, no? > So why don't we just rename kvm_write_guest_cached() to > kvm_write_guest(), and the few places - if any - that need to force > transversing of the gfn mappings, get renamed to > kvm_write_guest_uncached ? > Good idea. I do not see any places where kvm_write_guest_uncached is needed from a brief look. Avi? > >>+ &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. > Sorry, missed that the first time I've read your e-mail. > > If done like you said, time spent on the hypervisor is accounted as > steal time. I don't think it is. I thought that this is the point of a steal time. Running other tasks/guests is a hypervisor overhead too after all :) Also what about time spend serving host interrupts between put/get? It will not be accounted as steal time, correct? > > Steal time is time spent running someone else's job instead of > yours. The name for the time spent in the hypervisor doing something > for *you* is just overhead. OK. That is the question of a definition I guess. If you define it like that the code is correct. > > > > >> 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. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/