On Wed, Jun 12, 2024 at 9:19 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > On Mon, 06 May 2024 18:17:48 +0800, Yi Wang wrote: > > From: Yi Wang <foxywang@xxxxxxxxxxx> > > > > We found that it may cost more than 20 milliseconds very accidentally > > to enable cap of KVM_CAP_SPLIT_IRQCHIP on a host which has many vms > > already. > > > > The reason is that when vmm(qemu/CloudHypervisor) invokes > > KVM_CAP_SPLIT_IRQCHIP kvm will call synchronize_srcu_expedited() and > > might_sleep and kworker of srcu may cost some delay during this period. > > One way makes sence is setup empty irq routing when creating vm and > > so that x86/s390 don't need to setup empty/dummy irq routing. > > > > [...] > > Applied to kvm-x86 generic, with a lot of fixup. A sanity check on the end > result would be much appreciated. Thanks! The code LGTM. I did some tests in my Intel machine and found no problems. Thanks for your work :) > > [1/3] KVM: Setup empty IRQ routing when creating a VM > https://github.com/kvm-x86/linux/commit/fbe4a7e881d4 > [2/3] KVM: x86: Don't re-setup empty IRQ routing when KVM_CAP_SPLIT_IRQCHIP > https://github.com/kvm-x86/linux/commit/e3c89f5dd11d > [3/3] KVM: s390: Don't re-setup dummy routing when KVM_CREATE_IRQCHIP > https://github.com/kvm-x86/linux/commit/c4201bd24f4a > > -- > https://github.com/kvm-x86/linux/tree/next --- Best wishes Yi Wang
