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([2001:b07:6468:f312:657f:501:149f:5617]) by smtp.gmail.com with ESMTPSA id y16sm1641866wru.28.2019.06.06.05.04.13 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 05:04:13 -0700 (PDT) Subject: Re: [patch 2/3] kvm: x86: add host poll control msrs To: Marcelo Tosatti , kvm-devel Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Andrea Arcangeli , "Rafael J. Wysocki" , Peter Zijlstra , Wanpeng Li , Konrad Rzeszutek Wilk , Raslan KarimAllah , Boris Ostrovsky , Ankur Arora , Christian Borntraeger References: <20190603225242.289109849@amt.cnet> <20190603225254.292226777@amt.cnet> From: Paolo Bonzini Message-ID: Date: Thu, 6 Jun 2019 14:04:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190603225254.292226777@amt.cnet> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org > Add an MSRs which allows the guest to disable > host polling (specifically the cpuidle-haltpoll, > when performing polling in the guest, disables > host side polling). > > Signed-off-by: Marcelo Tosatti Queued this patch while waiting for Rafal's review. Paolo > --- > Documentation/virtual/kvm/msr.txt | 9 +++++++++ > arch/x86/include/asm/kvm_host.h | 2 ++ > arch/x86/include/uapi/asm/kvm_para.h | 2 ++ > arch/x86/kvm/Kconfig | 1 + > arch/x86/kvm/cpuid.c | 3 ++- > arch/x86/kvm/x86.c | 23 +++++++++++++++++++++++ > 6 files changed, 39 insertions(+), 1 deletion(-) > > Index: linux-2.6.git/Documentation/virtual/kvm/msr.txt > =================================================================== > --- linux-2.6.git.orig/Documentation/virtual/kvm/msr.txt 2018-05-18 15:40:19.697438928 -0300 > +++ linux-2.6.git/Documentation/virtual/kvm/msr.txt 2019-06-03 19:37:49.618543527 -0300 > @@ -273,3 +273,12 @@ > guest must both read the least significant bit in the memory area and > clear it using a single CPU instruction, such as test and clear, or > compare and exchange. > + > +MSR_KVM_POLL_CONTROL: 0x4b564d05 > + Control host side polling. > + > + data: Bit 0 enables (1) or disables (0) host halt poll > + logic. > + KVM guests can disable host halt polling when performing > + polling themselves. > + > Index: linux-2.6.git/arch/x86/include/asm/kvm_host.h > =================================================================== > --- linux-2.6.git.orig/arch/x86/include/asm/kvm_host.h 2019-05-29 14:46:14.516005546 -0300 > +++ linux-2.6.git/arch/x86/include/asm/kvm_host.h 2019-06-03 19:37:49.619543530 -0300 > @@ -755,6 +755,8 @@ > struct gfn_to_hva_cache data; > } pv_eoi; > > + u64 msr_kvm_poll_control; > + > /* > * Indicate whether the access faults on its page table in guest > * which is set when fix page fault and used to detect unhandeable > Index: linux-2.6.git/arch/x86/include/uapi/asm/kvm_para.h > =================================================================== > --- linux-2.6.git.orig/arch/x86/include/uapi/asm/kvm_para.h 2019-01-04 12:07:15.936947406 -0200 > +++ linux-2.6.git/arch/x86/include/uapi/asm/kvm_para.h 2019-06-03 19:37:49.620543534 -0300 > @@ -29,6 +29,7 @@ > #define KVM_FEATURE_PV_TLB_FLUSH 9 > #define KVM_FEATURE_ASYNC_PF_VMEXIT 10 > #define KVM_FEATURE_PV_SEND_IPI 11 > +#define KVM_FEATURE_POLL_CONTROL 12 > > #define KVM_HINTS_REALTIME 0 > > @@ -47,6 +48,7 @@ > #define MSR_KVM_ASYNC_PF_EN 0x4b564d02 > #define MSR_KVM_STEAL_TIME 0x4b564d03 > #define MSR_KVM_PV_EOI_EN 0x4b564d04 > +#define MSR_KVM_POLL_CONTROL 0x4b564d05 > > struct kvm_steal_time { > __u64 steal; > Index: linux-2.6.git/arch/x86/kvm/Kconfig > =================================================================== > --- linux-2.6.git.orig/arch/x86/kvm/Kconfig 2019-05-29 14:46:14.530005593 -0300 > +++ linux-2.6.git/arch/x86/kvm/Kconfig 2019-06-03 19:37:49.620543534 -0300 > @@ -41,6 +41,7 @@ > select PERF_EVENTS > select HAVE_KVM_MSI > select HAVE_KVM_CPU_RELAX_INTERCEPT > + select HAVE_KVM_NO_POLL > select KVM_GENERIC_DIRTYLOG_READ_PROTECT > select KVM_VFIO > select SRCU > Index: linux-2.6.git/arch/x86/kvm/cpuid.c > =================================================================== > --- linux-2.6.git.orig/arch/x86/kvm/cpuid.c 2019-05-29 14:46:14.530005593 -0300 > +++ linux-2.6.git/arch/x86/kvm/cpuid.c 2019-06-03 19:37:49.621543537 -0300 > @@ -643,7 +643,8 @@ > (1 << KVM_FEATURE_PV_UNHALT) | > (1 << KVM_FEATURE_PV_TLB_FLUSH) | > (1 << KVM_FEATURE_ASYNC_PF_VMEXIT) | > - (1 << KVM_FEATURE_PV_SEND_IPI); > + (1 << KVM_FEATURE_PV_SEND_IPI) | > + (1 << KVM_FEATURE_POLL_CONTROL); > > if (sched_info_on()) > entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); > Index: linux-2.6.git/arch/x86/kvm/x86.c > =================================================================== > --- linux-2.6.git.orig/arch/x86/kvm/x86.c 2019-05-29 14:46:14.537005616 -0300 > +++ linux-2.6.git/arch/x86/kvm/x86.c 2019-06-03 19:37:49.624543547 -0300 > @@ -1177,6 +1177,7 @@ > MSR_IA32_POWER_CTL, > > MSR_K7_HWCR, > + MSR_KVM_POLL_CONTROL, > }; > > static unsigned num_emulated_msrs; > @@ -2628,6 +2629,14 @@ > return 1; > break; > > + case MSR_KVM_POLL_CONTROL: > + /* only enable bit supported */ > + if (data & (-1ULL << 1)) > + return 1; > + > + vcpu->arch.msr_kvm_poll_control = data; > + break; > + > case MSR_IA32_MCG_CTL: > case MSR_IA32_MCG_STATUS: > case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1: > @@ -2877,6 +2886,9 @@ > case MSR_KVM_PV_EOI_EN: > msr_info->data = vcpu->arch.pv_eoi.msr_val; > break; > + case MSR_KVM_POLL_CONTROL: > + msr_info->data = vcpu->arch.msr_kvm_poll_control; > + break; > case MSR_IA32_P5_MC_ADDR: > case MSR_IA32_P5_MC_TYPE: > case MSR_IA32_MCG_CAP: > @@ -8874,6 +8886,10 @@ > msr.host_initiated = true; > kvm_write_tsc(vcpu, &msr); > vcpu_put(vcpu); > + > + /* poll control enabled by default */ > + vcpu->arch.msr_kvm_poll_control = 1; > + > mutex_unlock(&vcpu->mutex); > > if (!kvmclock_periodic_sync) > @@ -9948,6 +9964,13 @@ > } > EXPORT_SYMBOL_GPL(kvm_vector_hashing_enabled); > > +bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) > +{ > + return (vcpu->arch.msr_kvm_poll_control & 1) == 0; > +} > +EXPORT_SYMBOL_GPL(kvm_arch_no_poll); > + > + > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq); > >