Messages in this thread | | | Date | Mon, 2 May 2022 18:18:39 +0200 | From | Paolo Bonzini <> | Subject | Re: [PATCH v9 0/9] IPI virtualization support for VM |
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On 4/19/22 17:31, Zeng Guang wrote: > Currently, issuing an IPI except self-ipi in guest on Intel CPU > always causes a VM-exit. It can lead to non-negligible overhead > to some workloads involving frequent IPIs when running in VMs. > > IPI virtualization is a new VT-x feature, targeting to eliminate > VM-exits on source vCPUs when issuing unicast, physical-addressing > IPIs. Once it is enabled, the processor virtualizes following kinds > of operations that send IPIs without causing VM-exits: > - Memory-mapped ICR writes > - MSR-mapped ICR writes > - SENDUIPI execution > > This patch series implements IPI virtualization support in KVM. > > Patches 1-4 add tertiary processor-based VM-execution support > framework, which is used to enumerate IPI virtualization. > > Patch 5 handles APIC-write VM exit due to writes to ICR MSR when > guest works in x2APIC mode. This is a new case introduced by > Intel VT-x. > > Patch 6 cleanup code in vmx_refresh_apicv_exec_ctrl(). Prepare for > IPIv status dynamical update along with APICv status change. > > Patch 7 move kvm_arch_vcpu_precreate() under kvm->lock protection. > This patch is prepared for IPIv PID-table allocation prior to > the creation of vCPUs. > > Patch 8 provide userspace capability to set maximum possible VCPU > ID for current VM. IPIv can refer to this value to allocate memory > for PID-pointer table. > > Patch 9 implements IPI virtualization related function including > feature enabling through tertiary processor-based VM-execution in > various scenarios of VMCS configuration, PID table setup in vCPU > creation and vCPU block consideration.
I queued it, but I am not going to send it to Linus until I get selftests for KVM_CAP_MAX_VCPU_ID. Selftests are generally _not_ optional for new userspace API.
Please send a patch on top of kvm/queue.
Paolo
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