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([2001:b07:6468:f312:c46c:2acb:d8d2:21d8]) by smtp.gmail.com with ESMTPSA id c6sm4140610wrb.60.2019.09.17.10.05.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Sep 2019 10:05:19 -0700 (PDT) Subject: Re: [PATCH v8 0/3] KVM: x86: Enable user wait instructions To: Tao Xu , rkrcmar@redhat.com, sean.j.christopherson@intel.com, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, jingqi.liu@intel.com References: <20190716065551.27264-1-tao3.xu@intel.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Tue, 17 Sep 2019 19:05:17 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/09/19 03:28, Tao Xu wrote: > On 7/20/2019 1:18 AM, Paolo Bonzini wrote: >> On 19/07/19 08:31, Tao Xu wrote: >>> Ping for comments :) >> >> Hi, I'll look at it for 5.4, right after the merge window. >> >> Paolo >> > Hi paolo, > > Linux 5.3 has released, could you review these patches. Thank you very > much! > > Tao >>> On 7/16/2019 2:55 PM, Tao Xu wrote: >>>> UMONITOR, UMWAIT and TPAUSE are a set of user wait instructions. >>>> >>>> UMONITOR arms address monitoring hardware using an address. A store >>>> to an address within the specified address range triggers the >>>> monitoring hardware to wake up the processor waiting in umwait. >>>> >>>> UMWAIT instructs the processor to enter an implementation-dependent >>>> optimized state while monitoring a range of addresses. The optimized >>>> state may be either a light-weight power/performance optimized state >>>> (c0.1 state) or an improved power/performance optimized state >>>> (c0.2 state). >>>> >>>> TPAUSE instructs the processor to enter an implementation-dependent >>>> optimized state c0.1 or c0.2 state and wake up when time-stamp counter >>>> reaches specified timeout. >>>> >>>> Availability of the user wait instructions is indicated by the presence >>>> of the CPUID feature flag WAITPKG CPUID.0x07.0x0:ECX[5]. >>>> >>>> The patches enable the umonitor, umwait and tpause features in KVM. >>>> Because umwait and tpause can put a (psysical) CPU into a power saving >>>> state, by default we dont't expose it to kvm and enable it only when >>>> guest CPUID has it. If the instruction causes a delay, the amount >>>> of time delayed is called here the physical delay. The physical >>>> delay is >>>> first computed by determining the virtual delay (the time to delay >>>> relative to the VM’s timestamp counter). >>>> >>>> The release document ref below link: >>>> Intel 64 and IA-32 Architectures Software Developer's Manual, >>>> https://software.intel.com/sites/default/files/\ >>>> managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf >>>> >>>> Changelog: >>>> v8: >>>>      Add vmx_waitpkg_supported() helper (Sean) >>>>      Add an accessor to expose umwait_control_cached (Sean) >>>>      Set msr_ia32_umwait_control in vcpu_vmx u32 and raise #GP when >>>>      [63:32] is set when rdmsr. (Sean) >>>>      Introduce a common exit helper handle_unexpected_vmexit (Sean) >>>> v7: >>>>      Add nested support for user wait instructions (Paolo) >>>>      Use the test on vmx->secondary_exec_control to replace >>>>      guest_cpuid_has (Paolo) >>>> v6: >>>>      add check msr_info->host_initiated in get/set msr(Xiaoyao) >>>>      restore the atomic_switch_umwait_control_msr()(Xiaoyao) >>>> >>>> Tao Xu (3): >>>>     KVM: x86: Add support for user wait instructions >>>>     KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL >>>>     KVM: vmx: Introduce handle_unexpected_vmexit and handle WAITPKG >>>> vmexit >>>> >>>>    arch/x86/include/asm/vmx.h      |  1 + >>>>    arch/x86/include/uapi/asm/vmx.h |  6 ++- >>>>    arch/x86/kernel/cpu/umwait.c    |  6 +++ >>>>    arch/x86/kvm/cpuid.c            |  2 +- >>>>    arch/x86/kvm/vmx/capabilities.h |  6 +++ >>>>    arch/x86/kvm/vmx/nested.c       |  5 ++ >>>>    arch/x86/kvm/vmx/vmx.c          | 83 >>>> ++++++++++++++++++++++++++------- >>>>    arch/x86/kvm/vmx/vmx.h          |  9 ++++ >>>>    arch/x86/kvm/x86.c              |  1 + >>>>    9 files changed, 101 insertions(+), 18 deletions(-) >>>> >>> >> > Queued, thanks. Paolo