Kvm X2apic, > > > > > > > > > AMD

Kvm X2apic, > > > > > > > > > AMD 工程师周日晚上发布了一个补丁系列，通过基于内核的虚拟机 (KVM) 获得了对 AMD SVM 驱动程序的 x2APIC 虚拟化“x2AVIC”支持。 AMD 对主线内核的虚拟化支持的某些领域并没有像预期的那样准 x2apic 在不同的 CPU 上可能叫法不一样，问题不大。 另外如果你的 CPU 不支持 x2apic 的话，可能是 BIOS 没有开启，我的华南 X99 是需要手动在 BIOS 里面开启的：在 【InterRCSetup】 - 【Processor The creation worked fine, also in the settings it shows "Acceleration: VT-x/AMD-V, Nested Paging, KVM Paravirtualization". This setting is enabled by default. 04(guest) on Ubuntu 20. The following features are enabled by default for any CPU model when KVM acceleration is enabled: kvm-msi-ext-dest-id feature is Unfortunately, QEMU does not emulate x2apic. In general is there significant increase in CPU performance in the host type vs. ) I know that > x2apic feature is in the kvm_default_props and automatically added to all > CPU models when KVM is enabled. Normally we try to keep the CPU model definitions as close as the real CPUs as Introducing AMD x2APIC Virtualization (x2AVIC) support. --x2apic on|off: Enables and disables CPU x2APIC support. 13. An improper check in svm_set_x2apic_msr_interception () may allow direct access to host x2apic msrs when the guest resets its apic, potentially leading to a denial of service IBM给出了答案：Red Hat Enterprise Linux 6 implements x2APIC emulation for KVM guests. We can either handle them all using hardware acceleration through the vgic or we can emulate a gic in user space and only drive CPU * Patch 16: New from Maxim * Patch 17: New from Maxim Best Regards, Suravee Maxim Levitsky (2): KVM: x86: nSVM: always intercept x2apic msrs KVM: x86: nSVM: optimize At the moment, the most concrete one is x2APIC spec, sorry. 4环境下，通过对比不同虚拟网卡和存储设备的性能，提出KVM虚拟化性能优化方案。使用systemtap工具分析vm exit原因及次数，结果表明virtio-net vhost网卡和virtio-blk存储设备性能 qemu -cpu qemu64,+ssse3,+sse4. Virt x2apic is a port of this feature for KVM, improving guest performance, especially for guests with many virtual processors. My host server is set up with kvm and is functioning well. When I create. Though regardless of whether your host CPU supports it, KVM can unconditionally emulate it for x86 guests, giving an Without it I had to switch video output before starting VM for some reason. Otherwise, KVM treats 0xff as a broadcast even Introducing support for AMD x2APIC virtualization. This feature is indicated by the CPUID Fn8000_000A EDX[14], and it can be activated by setting bit 31 (enable AVIC) and bit 30 As the title suggests, the steps you need to follow to speed up your VMs peformance using AMD AVIC. All tests pass when running virt-host-validate. A successful 3dmark score in question (with the 7770): Using hypercall to send IPIs by one vmexit instead of one by one for xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluster mode. GRUB by default boots Debian (5 seconds timeout) 4. 04 LTS minimal server. However, when starting the VM, it shows the green turtle icon and says: "native I'm now working on the initializing code of x2apic, but my qemu gives me this warning: qemu-system-x86_64: warning: TCG doesn't support requested feature: CPUID. Advanced programmable interrupt controllers (APICs) are used in symmetric multiprocessor (SMP) computer kvm的物理中断号来自于vfio，vfio_msi_set_vector_signal向系统申请物理中断号，传递给kvm，当外设触发中断后，IOMMU先处理，再给vcpu所有的物理cpu This page provides details about libvirt's domain XML format used for configuring and managing virtualized domains. 2,+x2apic To see the difference between the capabilities of the host CPU versus the guest, just compare the output of the following commands on each system: "AMD-Vi: Interrupt remapping enabled" "DMAR-IR: Enabled IRQ remapping in x2apic mode" ('x2apic' can be different on old CPUs, but should still work) 本文总结了KVM虚拟机启动时常见错误及注意事项，帮助用户快速解决问题，提高效率。 virtualize x2APIC mode：使能基于MSR方式对APIC寄存器的访问（x2API虚拟化）； APIC register virtualization： 控制APIC寄存器的访问方式（MMIO/MSR I am using ubuntu 22. 5. 7k次。本文解析了在KVM环境中启用x2APIC的原因，强调了虚拟化场景下性能提升，并详细介绍了不需中断重映射的条件和技术细节。 [ Upstream commit 73b42dc69be8564d4951a14d00f827929fe5ef79 ] Re-introduce the "split" x2APIC ICR storage that KVM used prior to Intel's IPI virtualization support KVM: X86: Implement PV IPIs support Using hypercall to send IPIs by one vmexit instead of one by one for xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluster The ioapic_debug and apic_debug have been not used for years, and kvm tracepoints are enough for debugging, so remove them as Paolo suggested. -machine type=pc-1. 15. 3 LTS I follow the following steps: 1 install qemu sudo apt-get install qemu 2 run 启用 X2APIC：IntelRCSetup - Processor Configuration - X2APIC X2APIC 在显卡直通的时候需要 另外就是跑大模型还可能需要 CPU 支持 AVX 指令集，精粤 X99 主板 BIOS 找不到这个设置项，实际上是 The kvm_amd driver needs to also keep track and set the VMCB bit 30 accordingly. Collection of scripts and tweaks for making a Windows 10 virtual machine run with QEMU/KVM/libvirt with GPU passthrough. 3-4 Kernel Version : Linux 5. 4 on Ubuntu 16. 2. Previously, with AVIC, guest needs to disable x2APIC capability and can only run in APIC mode to activate hardware-accelerated interrupt kvm: warning: host doesn't support requested feature: CPUID. See Section 3. Current software version: PVE: 7. Bug 2248122 (CVE-2023-5090) - CVE-2023-5090 kernel: KVM: SVM: improper check in svm_set_x2apic_msr_interception allows direct access to host x2apic msrs The guest can write the ‘MSR_KVM_PV_IPI’ to enable/disable this feature. Previously, with AVIC, guest needs to disable x2APIC capability and can only run in APIC mode to activate hardware Enabling KVM_X2APIC_API_USE_32BIT_IDS changes the behavior of KVM_SET_GSI_ROUTING, KVM_SIGNAL_MSI, KVM_SET_LAPIC, and KVM_GET_LAPIC, allowing the use of 32-bit APIC IDs. I have tested this +KVM_FEATURE_HC_MAP_GPA_RANGE 16 guest checks this feature bit before + using the map gpa range hypercall Hi there, I've used Proxmox for years on an old HP DL380 G6 which needs a patch to disable IOMMU RMRR checking and allow unsafe interrupts in order to passthrough GPU's to VM's. 04(host) with Intel® Core™ i3-1115G4. 0开始，任何x86 KVM VM都将自动启用x2apic，因此不需要显式选择。 来自qemu. It supports multiple QEMU accelerators: software emulation also known as TCG, hardware-assisted The article explores KVM virtualization infrastructure used by CocCoc, focusing on improving performance and stability through guest CPU flags. Keep this off as it's basically useless for retail products. Previously, with AVIC, guest needs to disable x2APIC capability and can only run in APIC mode to activate hardware-accelerated interrupt x2apic is a performance and scalability feature available in many modern Intel CPUs. An improper check in svm_set_x2apic_msr_interception () may allow direct access to host x2apic msrs when the guest resets its apic, potentially leading to a denial of service 本文参考：PVE开启硬件直通功能、PVE 7. Explanation of guest behavior 1. So 文章浏览阅读1. dd This is a quick example of how to configure Nvidia GPGPU pass through to a Linux KVM VM. If the guest disable this feature it will intercept ‘X2APIC_MSR (APIC_ICR)’ MSR and 中断虚拟化-内核端 由于历史原因，QEMU和KVM均独立实现了PIC、APIC(IOAPIC+LAPIC). (The x2APIC interface that you might see is paravirtualized. XMHF starts GRUB as a nested guest 3. The second half fixes a variety of AVIC and optimized APIC map bugs where KVM doesn't play nice with various PVE开启网卡直通，显卡直通，USB直通。 2021年9月更新 新版本的pve，例如pve7. Advanced programmable interrupt controllers (APICs) are used in A flaw was found in KVM. 1, “Motherboard Tab”. If you "PCI passthrough" a device, the device is not available to the host virsh adding x2apic, cache specific options to kvm config Ask Question Asked 10 years, 5 months ago Modified 9 years, 10 months ago AMD engineers on Sunday night sent out a patch series getting x2APIC virtualization 'x2AVIC' support for the AMD SVM driver with the Kernel-based IBM给出了答案： Red Hat Enterprise Linux 6 implements x2APIC emulation for KVM guests. 0. You can enable kvm_apic_set_state invokes kvm_lapic_set_base to disable x2APIC mode firstly, but don't change APIC_ID, APIC_ID is 32 bits in x2APIC mode and 8 bist(bit 24 ~ bit 31) in xAPIC x2apic feature is in the kvm_default_props and automatically added to all CPU models when KVM is enabled. 83-1 My Re: 7750 VSR-I 15. - PiMaker/Win10-VFIO Linux Kernel: [PATCH v5 13/33] KVM: SVM: Fix x2APIC Logical ID calculation for avic_kick_target_vcpus_fast 从QEMU2. IBM lab tests show that enabling the x2APIC support for Red Hat Enterprise Linux 6 guests can result in 2% to 5% throughput improvement for many I/O workloads. x2apic [bit 21] When I I have all nodes with exactly the same CPUs model , core count etc. 0，无需做驱动屏 How can I tell whether my processor has a particular feature? (64-bit instruction set, hardware-assisted virtualization, cryptographic accelerators, etc. virtual machine i want this to 可以配置是否启用“Intel超线程”、禁用内核和 x2APIC 支持。 x2APIC模式中，采用了 MSR （Model-specific register）方式来读取APIC的寄存器，取消了内存映 The libvirt KVM/QEMU driver can manage any QEMU emulator from version 6. Here is my story (or just KVM: x86: add a flag to disable KVM x2apic broadcast quirk Add KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK as a feature flag to The KVM API grew over time. But userspace devices don't support x2apic which can't be enabled Enabling Virtual-Interrupt Delivery in KVM What KVM does in software today: −Emulates APIC with the state maintained in Virtual-APIC page − Evaluates pending virtual interrupts − KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK must be enabled for x2APIC to work in logical mode or with more than 255 VCPUs. x2apic [bit 21] When I PCI passthrough allows you to use a physical PCI device (graphics card, network card) inside a VM (KVM virtualization only). 029291] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping. 0,accel=kvm -cpu qemu64,+x2apic -serial 深入解析IOMMU DMA重映射与中断处理机制，详解MSI中断原理、中断重映射技术优势及Linux内核实现。涵盖物理中断投递流程、中断隔离迁移方案，分析KVM From where the cpu capabilites are exposed to libvirt VM's? We are able the see different cpu capabilities from different sources. 2k次。最近给服务器装了kvm虚拟机，服务器上有多张显卡，想透传给虚拟机使用我的环境是ubuntu16. For this reason, KVM defines many constants of the form KVM_CAP_*, each corresponding to a set of functionality provided by one or more ioctls. 01H:ECX. intremap=no_x2apic_optout kernel option added to bypass motherboard firmware falsely reporting x2APIC method is not [ 0. ) vcpu_id is APIC ID I've checked qemu's source, and I've found a stupid patch that silently disables x2apic when irqchip is not used, so I've tried Code: Select all qemu-system-x86_64 -m 32 -d guest_errors -hda bin/disk. 文章浏览阅读3. 0 or later. You might not need to switch to a physical machine. 1,+sse4. But userspace devices don't support x2apic > which can't be enabled without the in-kernel A flaw was found in KVM. aes [bit 25] kvm: Host doesn't support requested features TASK ERROR: start failed: I suspect it's because kvm with a ryzen cpu appears to treat it as an EPYC cpu and the model just isn't recognized. x2apic is a performance and scalability feature available in many modern Intel CPUs. The kvm_amd driver needs to also keep track and set the VMCB bit 30 accordingly. 106591] DMAR-IR: Enabled IRQ x2apic is an x86 feature that improves performance, especially on large systems. 106413] DMAR-IR: x2apic is disabled because BIOS sets x2apic opt out bit. git: commit ef02ef5f4536dba090b12360a6c862ef0e57e3bc作者: Eduardo Habkost日期: Wed Feb 19 Trying to launch an SNP guest following the latest snp-latest branch (commit f801acaf89a45529d1a0985d2510c04a61fcda2c). Variants The xAPIC was introduced with the Pentium 4, while the x2APIC is the most recent generation of the Intel's programmable interrupt controller, 虚拟机IPI中断是虚拟化性能瓶颈，测试表明禁用HLT指令可大幅提升性能，但会降低物理机资源利用率。优化方案需平衡虚拟机性能与物理机经济效益，私有云可 Direct interrupt delivery Issue #3 The host and the guest use different vectors for the same devices Normal KVM host converts the host’s vector to the guest’s vector For Direct IRQ, PCI devices must This is an example of how to set up GPU passthrough in a virtual environment using KVM on Debian 12 Bookworm and use the GPU from a virtual machine. 041735] DMAR: No ATSR found [ Set x2apic=off (new patch-series are being reviewed, that would remove this requirement, but until then, you'll have to disable it). Debian executes 0xffffffff81062179 (can set a Yet Another IOMMU Not Detected Thread This is solved. CPU x2APIC support helps operating systems run more efficiently on This enables x2apic on the following CPU models: Conroe, Penryn, Nehalem, Westmere, Opteron_G[12345]. Availability of these The first half or so patches fix semi-urgent, real-world relevant APICv and AVIC bugs. 本文探讨了在Linux 4. You have to use KVM (or a different emulator). I installed qemu, qemu-kvm, bridge-utils and added my user to kvm The message "IRQ remapping doesn't support X2APIC mode, disable x2apic" is generated by kernel function `try_to_enable_x2apic () when there is environment where x2apic mode can't be enabled for 查了一些资料，当参数kvmintel nested=Y，KVM是基于host cpu的硬件特性进行虚拟化的，如果主机CPU不支持A [ 0. I have: Verified the BIOS settings Built and Introducing AMD x2APIC Virtualization (x2AVIC) support. 030627] DMAR-IR: Enabled IRQ remapping in x2apic mode [ 1. Paravirtualized KVM features are represented as CPU flags. This I'm tying to install Ubuntu 22. We have 2 modes for dealing with interrupts in the ARM world. 04. Some VMs support nested Introducing AMD x2APIC Virtualization (x2AVIC) support. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and I want to use QEMU to debug my compiled kernel linux-4. [ 0. More details on AMD's x2APIC virtualization support for Linux KVM usage via this patch series. 106414] DMAR-IR: Use 'intremap=no_x2apic_optout' to override the BIOS setting. This guid is for Intel hardware, but a similar approach can be take for 然后使用虚拟中断向量，将 PID: PIR(PID[255:0]) 中 V 对应的位置 1。 最后将 PID: NDST(PID[319:288]) 和 PID: NV(PID[279:272]) 填入 ICR (xAPIC 和 x2APIC 有略微区别)，以发送 IPI 通知。 由于 IPIv 大 TL;DR: KVM's AVIC and optimized APIC map code doesn't correctly handle various edge cases that are architecturally legal(ish), but are unlikely to occur in most real world scenarios. KVM currently supports only xAPIC, which has 8 bit APIC ID. BIOS boots XMHF 2. default kvm64 . 0R4 in EVE-NG by mienk » Thu Nov 12, 2020 4:55 am add "+x2apic" with following sample. 01IOMMUdmesg | grep -i -e kvm_apic_set_state invokes kvm_lapic_set_base to disable x2APIC mode firstly, but don't change APIC_ID, APIC_ID is 32 bits in x2APIC mode and 8 bist(bit 24 ~ bit 31) in xAPIC mode. Though regardless of whether your host CPU supports it, KVM can unconditionally emulate it With x2AVIC, the guest OS can also switch between APIC and x2APIC modes during runtime. We created a VM with cpu mode 'host-passthrough' which didn't KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. 3 优化和显卡直通、PVE开启硬件显卡直通功能、PVE设置显卡直通、proxmox PCI Passthrough、Proxmox VE 11代-12 Hello dear Proxmox Community! :) I'm trying to set up GPU Passthrough with my Nvidia RTX 3090, but i can't get my card to work. I was going to post this as a question but I solved it so now I'm posting it so that others will not follow in my footsteps. Intel guest can enter x2apic cluster mode when I'm now working on the initializing code of x2apic, but my qemu gives me this warning: qemu-system-x86_64: warning: TCG doesn't support requested feature: CPUID. 本文档试图说明清楚KVM中实现的PIC和APIC的逻辑。 文章浏览阅读6. 8k次。本节分析APIC控制器在kvm/qemu中的虚拟化原理与流程_apic虚拟化 The guest timer interrupt is > > > > > > > > injected > > > > > > > > by posted-interrupt which is delivered by housekeeping cpu once > > > > > > > > the emulated > > > > > > > > timer fires. glzb5, mrkhca, dyzt0n, jdqfb, vxdid, wgbp, 2udxz2, iwnrx, of2w6, bkky,