CHANGES FROM RFCv4: ================== (https://lkml.org/lkml/2016/4/7/87) * Removing the RFC since I think this is getting ready. * Rebase to latest tip.git. * Rename vm_deinit to vm_destroy. * Replace svm_vcpu_avic_enabled() with kvm_vcpu_apicv_active(). * Fix the cluster logical APIC ID calculation logic. * Misc clean up based on previous review comments. * (NEW) Rename kvm_lapic_get_reg to kvm_lapic_get_reg. * (NEW) Introduce kvm_x86_ops.apicv_post_state_restore hook. * (NEW) Re-factor the VMEXIT handling code and reuse it in the apicv_post_state_restore to implement support for vmsave/restore, which has been tested migrating: - from AVIC mode to non-AVIC mode - from non-AVIC mode to AVIC mode * (NEW) Add support for the AVIC VMCB clean bit. GITHUB ====== Latest git tree can be found at: http://github.com/ssuthiku/linux.git avic_part1_v5 OVERVIEW ======== This patch set is the first of the two-part patch series to introduce the new AMD Advance Virtual Interrupt Controller (AVIC) support. Basically, SVM AVIC hardware virtualizes local APIC registers of each vCPU via the virtual APIC (vAPIC) backing page. This allows guest access to certain APIC registers without the need to emulate the hardware behavior in the hypervisor. More information about AVIC can be found in the AMD64 Architecture Programmer’s Manual Volume 2 - System Programming. http://support.amd.com/TechDocs/24593.pdf For SVM AVIC, we extend the existing kvm_amd driver to: * Check CPUID to detect AVIC support in the processor * Program new fields in VMCB to enable AVIC * Introduce new AVIC data structures and add code to manage them * Handle two new AVIC #VMEXITs * Add new interrupt intjection code using vAPIC backing page instead of the existing V_IRQ, V_INTR_PRIO, V_INTR_VECTOR, and V_IGN_TPR fields Currently, this patch series does not enable AVIC by default. Users can enable SVM AVIC by specifying avic=1 during insmod kvm-amd. Later, in part 2, we will introduce the IOMMU AVIC support, which provides speed up for PCI device pass-through use case by allowing the IOMMU hardware to inject interrupt directly into the guest via the vAPIC backing page. PERFORMANCE RESULTS =================== Currently, AVIC is supported in the AMD family 15h models 6Xh (Carrizo) processors. Therefore, it is used to collect the perforamance data shown below. Generaly, SVM AVIC alone (w/o IOMMU AVIC) should provide speedup for IPI interrupt since hypervisor does not require VMEXIT to inject these interrupts. Also, it should speed up the case when hypervisor wants to inject an interrupt into a running guest by setting the corresponded IRR bit in the vAPIC backing page and trigger AVIC_DOORBELL MSR. IPI PERFORMANCE =============== * BENCHMARK 1: HACKBENCH For IPI, I have collected some performance number on 2 and 4 CPU running hackbech with the following detail: hackbench -p -l 100000 Running in process mode with 10 groups using 40 file descriptors each (== 400 tasks) Each sender will pass 100000 messages of 100 bytes | 2 vcpus | 4 vcpus ------------------------------------------------ Vanila | 273.76 | 190.21 AVIC disabled | 260.51 (~5%) | 184.40 (~5%) AVIC | 248.53 (~10%) | 155.01 (~20%) OVERALL PERFORMANCE =================== Enabling AVIC should helps speeding up workloads, which generate large amount of interrupts. However, it requires additional logics to maintain AVIC-specific data structures during vCPU load/unload due to vcpu scheduling. The goal is to minimize the overhead of AVIC in most cases, so that we can achieve equivalent or improvement in overall performance when enabling AVIC. * BENCHMARK 1: TAR DECOMPRESSION This test measures the average running time (of 10 runs) of the following tar decompression command with 1, 2, and 4 vcpus. tar xf linux-4.3.3.tar.xz | 4 vcpus --------------------------------- Vanila | 10.26 AVIC disabled | 10.10 (~1.5%) AVIC | 10.07 (~1.8%) Note: The unit of result below is in seconds (lower is better). * BENCHMARK 2: NETPERF w/ virtual network This test creates a virtual network by setting up bridge and tap device on the host and pass it into the VM as virtio-net-pci device w/ vhost. Then it sets up netserver in the host machine, and run netperf in the VM with following option: netperf -H <netserver ip> -l 60 -t TCP_RR -D 2 | 1 vcpu ------------------------------------ Vanila | 21623.887 AVIC disabled | 21538.09 (~-.4%) AVIC | 21712.68 (~0.4%) Note: The unit of result below is trans/sec (higher is better). Preliminary result of both benchmarks show AVIC performance are slightly better than the other two cases. CURRENT UNTESTED USE-CASES =========================== - Nested VM Any feedback and comments are very much appreciated. Thank you, Suravee Radim Krčmář (1): KVM: split kvm_vcpu_wake_up from kvm_vcpu_kick Suravee Suthikulpanit (12): KVM: x86: Misc LAPIC changes to expose helper functions KVM: x86: Rename kvm_apic_get_reg to kvm_lapic_get_reg KVM: x86: Introducing kvm_x86_ops VM init/destroy hooks KVM: x86: Introducing kvm_x86_ops VCPU blocking/unblocking hooks svm: Introduce new AVIC VMCB registers KVM: x86: Detect and Initialize AVIC support svm: Add interrupt injection via AVIC svm: Add VMEXIT handlers for AVIC KVM: x86: Introducing kvm_x86_ops.apicv_post_state_restore svm: Do not expose x2APIC when enable AVIC svm: Do not intercept CR8 when enable AVIC svm: Manage vcpu load/unload when enable AVIC arch/x86/include/asm/kvm_host.h | 26 +- arch/x86/include/asm/svm.h | 12 +- arch/x86/include/uapi/asm/svm.h | 9 +- arch/x86/kvm/ioapic.c | 2 +- arch/x86/kvm/lapic.c | 187 +++++------- arch/x86/kvm/lapic.h | 38 ++- arch/x86/kvm/svm.c | 660 +++++++++++++++++++++++++++++++++++++++- arch/x86/kvm/trace.h | 57 ++++ arch/x86/kvm/x86.c | 7 + include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 19 +- 11 files changed, 891 insertions(+), 127 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
