On 09/10/21 04:11, Sean Christopherson wrote:
This is basically two series smushed into one. The first "half" aims to differentiate between "halt" and a more generic "block", where "halt" aligns with x86's HLT instruction, the halt-polling mechanisms, and associated stats, and "block" means any guest action that causes the vCPU to block/wait. The second "half" overhauls x86's APIC virtualization code (Posted Interrupts on Intel VMX, AVIC on AMD SVM) to do their updates in response to vCPU (un)blocking in the vcpu_load/put() paths, keying off of the vCPU's rcuwait status to determine when a blocking vCPU is being put and reloaded. This idea comes from arm64's kvm_timer_vcpu_put(), which I stumbled across when diving into the history of arm64's (un)blocking hooks. The x86 APICv overhaul allows for killing off several sets of hooks in common KVM and in x86 KVM (to the vendor code). Moving everything to vcpu_put/load() also realizes nice cleanups, especially for the Posted Interrupt code, which required some impressive mental gymnastics to understand how vCPU task migration interacted with vCPU blocking. Non-x86 folks, sorry for the noise. I'm hoping the common parts can get applied without much fuss so that future versions can be x86-only. v2: - Collect reviews. [Christian, David] - Add patch to move arm64 WFI functionality out of hooks. [Marc] - Add RISC-V to the fun. - Add all the APICv fun. v1: https://lkml.kernel.org/r/20210925005528.1145584-1-seanjc@xxxxxxxxxx Jing Zhang (1): KVM: stats: Add stat to detect if vcpu is currently blocking Sean Christopherson (42): KVM: VMX: Don't unblock vCPU w/ Posted IRQ if IRQs are disabled in guest KVM: SVM: Ensure target pCPU is read once when signalling AVIC doorbell KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPU KVM: Force PPC to define its own rcuwait object KVM: Update halt-polling stats if and only if halt-polling was attempted KVM: Refactor and document halt-polling stats update helper KVM: Reconcile discrepancies in halt-polling stats KVM: s390: Clear valid_wakeup in kvm_s390_handle_wait(), not in arch hook KVM: Drop obsolete kvm_arch_vcpu_block_finish() KVM: arm64: Move vGIC v4 handling for WFI out arch callback hook KVM: Don't block+unblock when halt-polling is successful KVM: x86: Tweak halt emulation helper names to free up kvm_vcpu_halt() KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt() KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt() KVM: Don't redo ktime_get() when calculating halt-polling stop/deadline KVM: x86: Directly block (instead of "halting") UNINITIALIZED vCPUs KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states KVM: Add helpers to wake/query blocking vCPU KVM: VMX: Skip Posted Interrupt updates if APICv is hard disabled KVM: VMX: Clean up PI pre/post-block WARNs KVM: VMX: Drop unnecessary PI logic to handle impossible conditions KVM: VMX: Use boolean returns for Posted Interrupt "test" helpers KVM: VMX: Drop pointless PI.NDST update when blocking KVM: VMX: Save/restore IRQs (instead of CLI/STI) during PI pre/post block KVM: VMX: Read Posted Interrupt "control" exactly once per loop iteration KVM: VMX: Move Posted Interrupt ndst computation out of write loop KVM: VMX: Remove vCPU from PI wakeup list before updating PID.NV KVM: VMX: Handle PI wakeup shenanigans during vcpu_put/load KVM: Drop unused kvm_vcpu.pre_pcpu field KVM: Move x86 VMX's posted interrupt list_head to vcpu_vmx KVM: VMX: Move preemption timer <=> hrtimer dance to common x86 KVM: x86: Unexport LAPIC's switch_to_{hv,sw}_timer() helpers KVM: x86: Remove defunct pre_block/post_block kvm_x86_ops hooks KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs KVM: SVM: Unconditionally mark AVIC as running on vCPU load (with APICv) KVM: Drop defunct kvm_arch_vcpu_(un)blocking() hooks KVM: VMX: Don't do full kick when triggering posted interrupt "fails" KVM: VMX: Wake vCPU when delivering posted IRQ even if vCPU == this vCPU KVM: VMX: Pass desired vector instead of bool for triggering posted IRQ KVM: VMX: Fold fallback path into triggering posted IRQ helper KVM: VMX: Don't do full kick when handling posted interrupt wakeup arch/arm64/include/asm/kvm_emulate.h | 2 + arch/arm64/include/asm/kvm_host.h | 1 - arch/arm64/kvm/arch_timer.c | 5 +- arch/arm64/kvm/arm.c | 60 +++--- arch/arm64/kvm/handle_exit.c | 5 +- arch/arm64/kvm/psci.c | 2 +- arch/mips/include/asm/kvm_host.h | 3 - arch/mips/kvm/emulate.c | 2 +- arch/powerpc/include/asm/kvm_host.h | 4 +- arch/powerpc/kvm/book3s_pr.c | 2 +- arch/powerpc/kvm/book3s_pr_papr.c | 2 +- arch/powerpc/kvm/booke.c | 2 +- arch/powerpc/kvm/powerpc.c | 5 +- arch/riscv/include/asm/kvm_host.h | 1 - arch/riscv/kvm/vcpu_exit.c | 2 +- arch/s390/include/asm/kvm_host.h | 4 - arch/s390/kvm/interrupt.c | 3 +- arch/s390/kvm/kvm-s390.c | 7 +- arch/x86/include/asm/kvm-x86-ops.h | 4 - arch/x86/include/asm/kvm_host.h | 29 +-- arch/x86/kvm/lapic.c | 4 +- arch/x86/kvm/svm/avic.c | 95 ++++----- arch/x86/kvm/svm/svm.c | 8 - arch/x86/kvm/svm/svm.h | 14 -- arch/x86/kvm/vmx/nested.c | 2 +- arch/x86/kvm/vmx/posted_intr.c | 279 ++++++++++++--------------- arch/x86/kvm/vmx/posted_intr.h | 14 +- arch/x86/kvm/vmx/vmx.c | 63 +++--- arch/x86/kvm/vmx/vmx.h | 3 + arch/x86/kvm/x86.c | 55 ++++-- include/linux/kvm_host.h | 27 ++- include/linux/kvm_types.h | 1 + virt/kvm/async_pf.c | 2 +- virt/kvm/kvm_main.c | 138 +++++++------ 34 files changed, 413 insertions(+), 437 deletions(-)
Queued 1-20 and 22-28. Initially I skipped 21 because I didn't receive it, but I have to think more about whether I agree with it.
In reality the CMPXCHG loops can really fail just once, because they only race with the processor setting ON=1. But if the warnings were to trigger at all, it would mean that something iffy is happening in the pi_desc->control state machine, and having the check on every iteration is (very marginally) more effective.
It's all theoretical, granted. Paolo
