Messages in this thread | | | Subject | Re: [PATCH v8 0/3] KVM: x86: Enable user wait instructions | From | Tao Xu <> | Date | Sat, 20 Jul 2019 15:14:20 +0800 |
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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 > Thank you Paolo!
>> 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(-) >>> >> >
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