Kvm x2apic. org> To: stable@vger.

Kvm x2apic joey@xxxxxxxxxxxxx>; Date: Sat, 5 Sep 2020 20:21:15 +0800; Cc: pbonzini@xxxxxxxxxx, rkrcmar Mar 31, 2021 · I am trying to use KVM with QEMU. Besides, for x2AVIC, kvm_amd driver needs to disable interception for the x2APIC MSR range to allow AVIC hardware to virtualize register accesses. >> > > No, i don't think it is a windows bug, it has nothing to do with x2apic, hv-vapic MSRs doesn't provide any performance improvement over x2apic MSRs. 211053] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping. 096911] DMAR: dmar0: reg_base_addr fbffd000 ver 1:0 cap Why using KVM? • non-KVM solutions –Some RTOS supports Linux guests –Tiny hypervisors just for partitioning • KVM has … –Advanced virtualization features •Sharing and overcommit resources •Support virtualization hardware (EPT, x2APIC, VT-d, ) •Well-defined management / debug interfaces (e. 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 (x2APIC mode) of VMCB offset 60h. 12. device_irq_level +set exactly once per edge signal. 04 KVM GPU Passthrough. 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: grep flags /proc/cpuinfo | uniq For example, the default setting on a 64 bit host machine is "-cpu qemu64". 40GHz x86 kvm64 Common KVM processor x86 qemu32 QEMU Virtual CPU version 2. Dec 26, 2024 · From: Sasha Levin <sashal@kernel. c in int kvm_cpu_exec(CPUState *cpu) in the cycle right before run_ret = kvm_vcpu_ioctl(cpu, KVM_RUN, 0); call. Eariler in the week I posted a thread on reddit about IOMMU AVIC getting some fixes/improvements allowing for easier general usage. ko，分别对应不同的CPU厂商。 在一些Linux发行版中存在名为qemu-kvm的软件包，它提供了一个名为kvm的脚本，在Ubuntu上可以通过apt install -y qemu-kvm来安装。 qemu -cpu qemu64,+ssse3,+sse4. Note If the x2APIC mode is enabled in BIOS, you cannot disable the x2APIC mode by using the options of the bcdedit command. - furthermore, for x2apic: here and here for example. Though regardless of whether your host CPU supports it, KVM can unconditionally emulate it for x86 guests, giving an easy performance win with no downside. Sep 18, 2021 · Subject: Re: [PATCH v4 5/6] KVM: x86: Support interrupt dispatch in x2APIC mode with APIC-write VM exit: From: Zeng Guang <> Date: Sat, 18 Sep 2021 00:00:15 +0800 May 12, 2021 · Hello! I'm currently trying to implement the SMP architecture in an Operating System, with the x86_64 architecture. Disable x2APIC Before Booting Oracle Hardware Installation Assistant (CR 7112255) Documentation Errata; Broken Links in Sun Server X2-8 Documentation Library; Use On 21/12/17 13:51, Paolo Bonzini wrote: Remove duplicate expression in nested_vmx_prepare_msr_bitmap, and make the register names clearer in hardware_setup. lan@intel. Jun 30, 2023 · virsh adding x2apic, cache specific options to kvm config. Performance counter Sep 4, 2019 · The flaw arises from improper handling of x2APIC Machine Specific Register (MSR) access when nested virtualization is enabled, potentially exposing the host to security risks. 3 x86 phenom AMD Phenom(tm) 9550 Quad-Core Processor x86 core2duo Intel(R) Core(TM)2 Duo CPU T7700 @ 2. Feb 12, 2016 · Thank you, Suravee Suravee Suthikulpanit (9): KVM: x86: Misc LAPIC changes to exposes helper functions svm: Introduce new AVIC VMCB registers svm: clean up V_TPR, V_IRQ, V_INTR_PRIO, and V_INTR_MASKING KVM: x86: Detect and Initialize AVIC support svm: Add VMEXIT handlers for AVIC svm: Add interrupt injection via AVIC svm: Do not expose x2APIC Oct 13, 2016 · qemu-system-x86_64 -m 32 -d guest_errors -hda bin/disk. ko或kvm-amd. com> [ Sasha's Feb 25, 2016 · x2apic feature is in the kvm_default_props and automatically added to all CPU models when KVM is enabled. You might not need to switch to a physical machine. 6. Known limitations of CPU virtualization¶. 431646] DMAR: DRHD base: 0x000000fbffd000 flags: 0x0 [ 0. Either via modprobe or as kernel command-line argument when x2apic is exposed to the guest, even on current CPUs - it [PATCH v4 20/32] KVM: x86: Skip redundant x2APIC logical mode optimized cluster setup From: Sean Christopherson Date: Fri Sep 30 2022 - 21:02:50 EST Next message: Sean Christopherson: "[PATCH v4 22/32] KVM: x86: Disable APIC logical map if vCPUs are aliased in logical mode" Sep 20, 2022 · Sean Christopherson (27): KVM: x86: Blindly get current x2APIC reg value on "nodecode write" traps KVM: x86: Purge "highest ISR" cache when updating APICv state KVM: SVM: Flush the "current" TLB when activating AVIC KVM: SVM: Process ICR on AVIC IPI delivery failure due to invalid target KVM: x86: Don't inhibit APICv/AVIC if xAPIC ID mismatch Apr 12, 2022 · With x2AVIC, the guest OS can also switch between APIC and x2APIC modes during runtime. Nov 28, 2014 · x2apic is a performance and scalability feature available in many modern Intel CPUs. 760293-1-gavinguo@igalia. > > There is no hardware virtual timer on Intel for Oct 19, 2024 · the Aspeed as far as I understand is just for IPMI. x2apic is an x86 feature that improves performance, especially on large systems. “-machine …,kernel-irqchip=split -cpu …,x2apic”). 0 x86 kvm32 Common 32-bit KVM processor x86 coreduo Genuine Intel(R) CPU T2600 @ 2 [ 0. Keep reading the rest of the series: How to install KVM on CentOS 7 / RHEL 7 Headless Server; Install KVM on Ubuntu 16. Apr 12, 2014 · I have a VM on a host and want to create another VM within the existing VM (nested). 000000] DMAR: RMRR base: 0x000000dc315000 end Jul 23, 2018 · 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. img,index=1" from QEMU command line. 092607] DMAR: DRHD base: 0x000000fbffd000 flags: 0x0 [ 0. 000000 Sep 10, 2020 · The guest can write the ‘MSR_KVM_PV_IPI’ to enable/disable this feature. Intel guest can enter x2apic cluster mode when interrupt remmaping KVM: X86: Add $ dmesg | egrep 'DMAR|IOMMU' [ 0. When I create. x2apic [bit 21]" when kernel_irqchip is off. This will boot Debian directly (instead of booting XMHF and then boot Debian) 2. Jul 16, 2021 · Patches 1-3 add tertiary processor-based VM-execution support framework. 8. 5. Because of this advantage, KVM can and does emulate the x2APIC for older processors that do not physically support it, and this support is exposed from QEMU going back to Conroe and even for AMD Opteron G-series processors (neither of which natively support x2APIC). xml Add CPUID check for the x2APIC virtualization (x2AVIC) feature. + +The field run->s. org Cc: Gavin Guo <gavinguo@igalia. Feb 20, 2016 · 2016-02-20 17:00 GMT+08:00 Paolo Bonzini <pbonzini@redhat. I managed to find and parse the ACPI tables, I wrote the wake up sequence and the trampoline code, but the AP's do not wake up. Contribute to GiantVM/Book development by creating an account on GitHub. Contribute to intel/kvm-unit-tests-tdx development by creating an account on GitHub. Please refer this discussion. KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. 2. 096904] DMAR: DRHD base: 0x000000fbffd000 flags: 0x0 [ 0. apic; KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. This patch will let KVM think that x2APIC virtualization is not available. conf If you see a lot of warning messages in your 'dmesg' system log, add the following instead: echo "options kvm ignore_msrs=1 report_ignored_msrs=0" > /etc/modprobe. Vulnerability Detail . Unfortunately there is no guest that can take advantage of it since Linux doesn't (yet?) use x2apic if interrupt remapping is not enabled KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. Intel guest can enter x2apic cluster mode when interrupt remmaping is enabled in qemu, however, latest AMD EPYC still just supports xapic mode which can get great improvement by Exit-less IPIs. 092606] DMAR: Host address width 46 [ 0. 000000] DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap c0000020660462 ecap f0101a [ 0. 11. This includes the following flags: I have enabled the x2APIC on the host OS and want to generate the IPI at the host level itself(and not inside a VM). Some VMs support nested virtualization, which would allow you to use KVM inside your VM. 011947] ACPI: Reserving DMAR table memory at [mem 0x5c6ceb70-0x5c6cec43] [ 0. 619936] DMAR: IOMMU feature fl1gp_support inconsistent Feb 21, 2022 · The x2APIC virtualization support allows for VMs to have more than 255 CPU threads and allows for better performance than legacy APIC mode for virtualization. 1(Debian 1:2. User have reported that NVIDIA Kepler K80 GPUs need this in vmid. 009837] ACPI: Reserving DMAR table memory at [mem 0x5c6e6b70-0x5c6e6c33] [ 0. Sep 29, 2014 · KVM does not deliver x2APIC broadcast messages with physical mode. Sep 10, 2020 · The guest can write the ‘MSR_KVM_PV_IPI’ to enable/disable this feature. phys_map to optimize logical mode x2APIC interrupts by * reversing the LDR calculation to get cluster of APICs, i. On the Intel side for KVM virtualization with Linux 6. But beware. All tests pass when running virt-host-validate. 7, 96 CPUS Intel-Xeon, 256GB RAM (nested virt enabled in kvm) L1 VM: op Sep 5, 2020 · On Sat, 5 Sep 2020 at 20:22, 邓桥 <dengqiao. com> [ Sasha's Jul 18, 2018 · 查看 qemu-kvm 支持模拟哪些 CPU model [root@localhost bin]# qemu-kvm -cpu help x86 qemu64 QEMU Virtual CPU version 1. Apr 5, 2022 · With x2AVIC, the guest OS can also switch between APIC and x2APIC modes during runtime. i should mention that the OS is loaded by Multiboot, and it runs on KVM. Clean up the x2APIC MSR bitmap intereption code for L2, which is the last holdout of open coded bitmap manipulations. Set avic=1, nested=0 and sev=0 for kvm_amd. e. I tried to start the KVM machine by calling qemu-system-x86_64 my. The x2apic in /proc/cpuinfo shows capabilities of your CPU chip. 012821] ACPI: DMAR 0x000000005C6E6B70 0000CC (v01 ALASKA A M I 00000001 INTL 20091013) [ 0. 7 - drop add 2. de> >> To: "Eduardo Habkost Dec 26, 2024 · In fact, that commit is when KVM first started treating the x2APIC ID as readonly, apparently to fix some race: static inline u32 kvm_apic_id(struct kvm_lapic *apic) { - return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff; + /* To avoid a race between apic_base and following APIC_ID update when + * switching to x2apic_mode, the x2apic mode Mar 8, 2022 · With x2AVIC, the guest OS can also switch between APIC and x2APIC modes during runtime. Source code for the virtualization book . Virt x2apic is a port of this feature for KVM, improving guest performance, especially for guests with many virtual processors. May 10, 2024 · Ubuntu 24. 000000] ACPI: DMAR 0x00000000DC44CC70 0000BC (v01 A M I OEMDMAR 00000001 INTL 00000001) [ 0. x2apic emulation is available on KVM since 2009 (Linux 2. no * additional work is required. 0. Nov 23, 2021 · @@ -113,14 +113,13 @@ static inline u32 kvm_x2apic_id(struct kvm_lapic *apic) static bool kvm_can_post_timer_interrupt(struct kvm_vcpu *vcpu) Contribute to google/android-emulator-hypervisor-driver development by creating an account on GitHub. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better v Sep 5, 2020 · Subject: [RFC] KVM: X86: implement Passthrough IPI; From: 邓桥 <dengqiao. 022477] DMAR: IOMMU enabled [ 0. 8 machine and linux headers update patches - drop numa related patches (will post separately as unrelated) - change default mc->maxcpus only for q35 Changes since RFC: - use new KVM_CAP_X2APIC_API to detect x2APIC IDs support - rebase on top of 2. device_irq_level is available independent of +run->kvm_valid_regs or run->kvm_dirty_regs bits. You have to call kvm_vcpu_ioctl KVM_SET_CPUID2 with the new features. Add "-machine kernel_irqchip=off" to the QEMU command line 3. 04 LTS minimal server. 010922] ACPI: DMAR 0x000000007A5C3130 000108 (v01 ALASKA A M I 00000001 INTL 20091013) [ 0. max_cstate=0 intel_iommu=on iommu=pt transparent_hugepage=never default_hugepagesz=1GB hugepagesz=1GB hugepages=<number of hugepages> numa_balancing=disable kvm_intel. [PATCH 09/11] KVM: x86: Treat x2APIC's ICR as a 64-bit register, not two 32-bit regs From: Sean Christopherson Date: Fri Feb 04 2022 - 16:42:51 EST Next message: Sean Christopherson: "[PATCH 06/11] KVM: x86: WARN if KVM emulates an IPI without clearing the BUSY flag" $ qemu-system-x86_64 --version QEMU emulator version 2. 2,+x2apic. There is no hardcoding of flags in my solution. My host server is set up with kvm and is functioning well. com> wrote: > > This patch paravirtualize the IPI sending process in guest by exposing > posted interrupt capability to guest directly . 619934] DMAR: No SATC found [ 0. Specifically, support for the x2APIC architecture can be implemented in the local APIC unit. I'm now wondering do I have to switch to the physical machine to enable KVM and x2apic in order to use these features and continue my work Here is my command to start qemu: qemu-system-x86_64 -cpu qemu64,+x2apic -s -S -fda a. Oct 14, 2024 · On Mon, Oct 14, 2024, Sean Christopherson wrote: > On Mon, Oct 14, 2024, Kai Huang wrote: > > On Wed, 2024-10-09 at 11:17 -0700, Sean Christopherson wrote: Jul 27, 2021 · Rocky Linux 8 KVM GPU Passthrough. 0, there is Intel IPI virtualization support after it didn't end up getting pulled into Linux 5. 011924] ACPI: DMAR 0x000000005C6CEB70 0000D4 (v01 ALASKA A M I 00000001 INTL 20091013) [ 0. Besides setting bit VMCB bit 30 and 31, for x2AVIC, kvm_amd driver needs to disable interception for the x2APIC MSR range to allow AVIC hardware to virtualize register accesses. com> > > This patch tries to optimize x2apic physical destination mode, fixed delivery > mode single target IPI by delivering IPI to receiver immediately after sender > writes ICR vmexit to avoid various checks when possible. 16GHz Apr 28, 2022 · Ubuntu 22. 916024] DMAR: Host address width 46 [ 0. Otherwise, KVM treats 0xff as a broadcast even in x2APIC mode in order to support physical x2APIC without interrupt remapping. A flaw was found in the way KVM hypervisor handled x2APIC Machine Specific Rregister (MSR) access with nested(=1) virtualization enabled. qcow2 -enable-kvm but I'm getting this error: qemu-system-x86_64: -machine accel=kvm: No accelerator found. unified_cgroup_hierarchy=1 kvm. Configure GPU Passthrough for Virtual Machines: qemu-system-x86_64 -m 32 -d guest_errors -hda bin/disk. 000000] DMAR: dmar0: reg_base_addr fbffc000 ver 1:0 cap d2078c106f0466 ecap f020de [ 0. All existing PCI/MSI capable devices and IOxAPIC unit should work with the x2APIC extensions defined in this document. I checked sysctl -a | grep machdep. syzkaller, can trip a WARN. When playing a 1080p video using VLC player, the perf stat result of the KVM process is as follows. log: Jul 4, 2018 · From: Jingqi Liu <> Subject [PATCH v2] KVM: Expose the split lock detection feature to guest VM: Date: Wed, 4 Jul 2018 21:06:33 +0800 Re: [PATCH v3 12/14] KVM: x86: add a flag to disable KVM x2apic broadcast quirk From: Paolo Bonzini Date: Wed Jul 13 2016 - 11:31:57 EST Next message: Matthias Dahl: "Re: Page Allocation Failures/OOM with dm-crypt on software RAID10 (Intel Rapid Storage)" Dec 7, 2021 · On Wed, Nov 24, 2021, Aili Yao wrote: > When cpu-pm is successfully enabled, and hlt_in_guest is true and > mwait_in_guest is false, the guest cant't use Monitor/Mwait instruction Jun 23, 2019 · I've only used "-cpu host,+x2apic,+tsc-deadline", and it worked for me, but look: - all of fma, pcid, x2apic, tsc-deadline enabled for cpu "Haswell" here. ple_window=0 mitigations=auto kvm. Current code is srv@local ~$ qemu-system-x86_64 -cpu help x86 qemu64 QEMU Virtual CPU version 2. 619934] DMAR: No ATSR found [ 0. 000000] DMAR: Host address width 39 [ 0. nx_huge_pages=off security=apparmor mmio_stale_data=off tsx=off Feb 4, 2022 · int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data) {struct kvm_lapic *apic = vcpu->arch. The kvm_amd driver needs to also keep track and set the VMCB bit 30 accordingly. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface: - msr exits are faster than mmio (no page table walk, emulation) - no need to read back ICR to look at the busy bit - one 64 bit ICR write Jul 3, 2023 · GRUB_CMDLINE_LINUX_DEFAULT="resume=UUID=eb319a47-23e2-4b2b-ad27-4924407771e0 udev. . A flaw was discovered in the KVM hypervisor's handling of x2APIC MSR access with nested virtualization enabled. A guest could use this flaw to potentially crash the host kernel resulting in DoS issue. GDB stub is not very reliable when using KVM. uk> Currently, Linux as a hypervisor guest will enable x2apic only if there are no CPUs present at boot time with an APIC ID above 255. 39 has KVM support available False. org Bugzilla – Bug 82211 Cannot boot Xen under KVM with X2APIC enabled Last modified: 2015-04-08 08:36:51 UTC Remove "-drive media=disk,file=c. Dec 14, 2018 · We have to compare some measurements between a VM running on KVM and one without KVM. and now it says: gns3 vm 2. Apr 23, 2017 · Edge triggered interrupt +signals will exit to userspace with the bit in run->s. In previous platform, no CPU would produce APIC-write VM exit with exit qulification 300H when the "virtual x2APIC mode" VM-execution control was 1. 000000] ACPI: DMAR 0x00000000BD6483E0 0000B8 (v01 INTEL BDW 00000001 INTL 00000001) [ 0. From yesteday's working gns3 vm 2. ple_gap=0 kvm_intel. x2APIC is architected to ex tend from the xAPIC architecture while minimizing the impact on platform components. 009814] ACPI: DMAR 0x000000005C6E6B70 0000C4 (v01 ALASKA A M I 00000001 INTL 20091013) [ 0. Device (I/O) interrupts acceleration is provided by AVIC and x2AVIC. avic=1. > > Testing on Xeon Skylake server: > > The virtual IPI latency from sender send to receiver Jan 17, 2025 · AFAIK, there's no real world use > > case that benefits from the patch, the fix is purely to plug a hole where fuzzers, > > e. regs. de> >> To: "Eduardo Habkost Jun 23, 2019 · QEMU virtualizes x2APIC mode when using KVM (-enable-kvm option). Host: opensuse Tumbleweed, kernel 4. 0,id=hostpci1. ids=1002:73bf,1002:ab28,10ec:8161 hugepages=16384 systemd. max_cstate=0 processor. " Aug 4, 2022 · There are a few notable changes worth mentioning when it comes to KVM virtualization with Linux 6. In reply to: Eric W. Jan 16, 2025 · intremap=no_x2apic_optout intel_idle. The following features are enabled by default for any CPU model when KVM acceleration is enabled: kvm-msi-ext-dest-id feature is enabled by default in x2apic mode with split irqchip (e. git: commit Jul 23, 2018 · xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluster mode. libvirt) –Large community May 18, 2022 · Introducing support for AMD x2APIC virtualization. eager-split-size=n. I think, your host CPU has to support x2APIC (which is about guaranteed these days) for this to work. Mar 28, 2024 · IOMMU AVIC. sg_display=0 vfio-pci. org> () In-Reply-To: <20241226033847. 01H:ECX. + +If KVM_CAP_ARM_USER_IRQ is supported, the KVM_CHECK_EXTENSION ioctl returns a +number Feb 28, 2023 · AlmaLinux 9 KVM GPU Passthrough. − Decode and emulate guest instructions that access APIC (except x2APIC mode) − Except for Intel® VT FlexPriority, which virtualizes access to one APIC control Nov 12, 2021 · Unfortunately, QEMU does not emulate x2apic. 000000] DMAR: IOMMU enabled [ 0. kvm -cpu ?model x86 Opteron_G3 AMD Opteron 23xx (Gen 3 Class Opteron) x86 Opteron_G2 AMD Opteron 22xx (Gen 2 Class Opteron) x86 Opteron_G1 AMD Opteron 240 (Gen 1 Class Opteron) x86 Nehalem Intel Core i7 9xx (Nehalem Class Core i7) x86 Penryn Intel Core 2 Duo P9xxx (Penryn Class Core 2) x86 Conroe Intel Celeron_4x0 (Conroe/Merom Class Core 2 From: luferry <luferry@xxxxxxx> x2apic_eanbled() costs about 200 cycles when guest trigger halt pretty high, pi ops in hotpath Signed-off-by: luferry <luferry@xxxxxxx> Apr 8, 2015 · Kernel. org> Subject: Re: [PATCH 6. 04 LTS KVM GPU Passthrough. 39 back in today. - and for tsc-deadline msr here. com> > > > > Dedicated instances are currently disturbed by unnecessary jitter due > > to the emulated lapic timers fire on the same pCPUs which vCPUs resident. If available, the SVM driver can support both AVIC and x2AVIC modes when load the kvm_amd driver with avic=1. 1,+sse4. To check if x2APIC is enabled or not, I run the following command: sudo rdmsr 0x1b // IA32_APIC_BASE MSR to check the x2APIC status And according to Intel SDM bit 10 shows the x2APIC status. Enable the "x2APIC" mode in BIOS firmware After you install this hotfix on a computer that is running an x64-based version of Windows Server 2008 R2, you can enable the x2APIC mode in BIOS, and then you can start the computer. 0 x86 phenom AMD Phenom(tm) 9550 Quad-Core Processor x86 core2duo Intel(R) Core(TM)2 Duo CPU T7700 @ 2. lost_tick_policy=discard parameter provided Host environment Operating system: Gentoo Linux 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 Configuration】 里面可以打开 X2APIC 选项。 可以看到我们的 IOMMU 是支持中断映射 Virt x2apic Summary. 0,multifunction=on: vfio 0000:04:00. 212976] DMAR-IR: Enabled IRQ remapping in x2apic mode [ 0. log_priority=3 amd_iommu=force_enable iommu=pt amdgpu. Jun 17, 2019 · On Tue, 18 Jun 2019 at 21:36, Marcelo Tosatti <mtosatti@redhat. Biederman: "Re: [PATCH v5] enable x2APIC without interrupt remapping under KVM" Messages sorted by: Jun 20, 2020 · kvm: -device vfio-pci,host=0000:04:00. cpu. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better v Fixes: 5c127c85472c ("KVM: SVM: Adding support for configuring x2APIC MSRs interception") Cc: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Signed-off-by: Suravee Suthikulpanit <suravee. Freshen up the SDM/PRM comment, rename the function to make it abundantly clear the funky behavior is x2APIC specific, and explain _why_ vmcs01's bitmap is ignored (the previous comment was flat out wrong for x2APIC behavior). Jun 20, 2023 · Debian 12 Bookworm KVM GPU Passthrough. yi59@xxxxxxxxxx> åéï > The ioapic_debug and apic_debug have been not used Jul 5, 2023 · oh, i put gns3 vm 2. 916041] DMAR: dmar0: reg_base_addr fbffc000 ver 1:0 cap Jan 15, 2022 · Date: Sat, 15 Jan 2022 10:08:10 +0800: Subject: Re: [PATCH v5 5/8] KVM: x86: Support interrupt dispatch in x2APIC mode with APIC-write VM exit: From: Zeng Guang <> Jun 8, 2021 · From: Ashish Kalra <> Subject [PATCH v3 1/5] KVM: X86: Introduce KVM_HC_MAP_GPA_RANGE hypercall: Date: Tue, 8 Jun 2021 18:05:43 +0000 Jul 3, 2018 · 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. 195540] DMAR: IOMMU enabled [ 0. [ 0. 04 LTS. IOMMU AVIC will be enabled by default when kvm_amd. Patch 4 implement interrupt dispatch support in x2APIC mode with APIC-write VM exit. Inter-Process Interrupts (IPI) virtualization aims to eliminate VM-exits when issuing IPI A flaw was found in KVM related to improper checks in the function svm_set_x2apic_msr_interception(). If the guest disable this feature it will intercept ‘X2APIC_MSR(APIC_ICR)’ MSR and the ‘pvipi_enabled’ is fale. Re: [PATCH v2 04/23] KVM: x86: Inhibit AVIC SPTEs if any vCPU enables x2APIC From: Paolo Bonzini Date: Mon Sep 05 2022 - 18:02:18 EST Next message: Jason Vas Dias: "SIGIO with si_code==POLL_HUP on read pipe FD with no writers?" Nov 9, 2019 · On 09/11/19 08:05, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent. 0,bus=ich9-pcie-port-2,addr=0x0. 916026] DMAR: DRHD base: 0x000000fbffc000 flags: 0x0 [ 0. 6] KVM: x86: Make x2APIC ID 100% readonly Date: Thu, 26 Dec 2024 11:44:21 -0500 [thread overview] Message-ID: <20241226003046-d8036c5ed2dc4589@stable. conf Nvidia Tips. Hot Network Questions how to combine two math symbols Jul 10, 2018 · Building on Jo-Erlend Schinstad's answer: Install cpu-checker $ sudo apt-get update $ sudo apt-get install cpu-checker Then check: $ kvm-ok If the CPU is enabled, you should see something like: When enabled, KVM will instead record dirty pages in a bitmap. 000000] DMAR: DRHD base: 0x000000fed90000 flags: 0x0 [ 0. 19. Jun 23, 2019 · QEMU virtualizes x2APIC mode when using KVM (-enable-kvm option). joey@bytedance. com> x2apic feature is in the kvm_default_props and automatically added to all CPU models when KVM is enabled. [18][19] May 7, 2022 · Then, it keeps track of each vCPU's APIC mode, and updates VMCB bit 30 to enable/disable x2APIC virtualization mode accordingly. 9 ICR Operation in x2APIC Mode) states: "A destination ID value of FFFF_FFFFH is used for broadcast of interrupts in both logical destination and physical destination modes. But kvm emulation also works for all of these, so if the OP can do kvm, they definitely should. > > > > That said, this is essentially a prerequisite for "KVM: x86: Re-split x2APIC ICR > > into ICR+ICR2 for AMD (x2AVIC)"[*], and it's relatively low risk, so I'm not > > opposed to Re: [PATCH] KVM: SVM: Fix x2apic logical cluster mode decoding and sanity check From: Suthikulpanit, Suravee Date: Thu Sep 15 2022 - 18:47:40 EST Next message: Lad, Prabhakar: "Re: [PATCH v3 08/10] riscv: dts: renesas: Add minimal DTS for Renesas RZ/Five SMARC EVK" $ dmesg | egrep 'DMAR|IOMMU' [ 0. virtual machine i want this to support kvm also and I am trying to make all the checks to pass when running virt-host-validate on the Virtual Machine, which is laso ubuntu 22. Yep, more vCPUs! This code gets AMD x2APIC virtualization (x2AVIC) squared away for their KVM kernel code. com>, Sasha Levin <sashal@kernel. 021188] DMAR: IOMMU enabled [ 0. com>: > > > ----- Original Message ----->> From: "Jan Kiszka" <jan. Because in kvm_vm_ioctl_check_extension function: #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT case KVM_CAP_IOMMU: r = iommu_present(&pci_bus_type); break; #endif No this option, the function returns 0 directly. KVM implements dirty page logging at the PAGE_SIZE granularity and enabling dirty-logging on a huge-page requires breaking it into PAGE_SIZE pages in the first place. _tsc arch_perfmon nopl xtopology tsc_reliable nonstop_tsc cpuid pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe Dec 11, 2014 · On 11/12/2014 13:53, zhanghailiang wrote: > > >> I think it's a Windows bug---it should prefer x2apic to hv-vapic if both >> are available. 012855] ACPI: Reserving DMAR table memory at [mem 0x5c6e6b70-0x5c6e6c3b] [ 0. Whenever perfect emulation of a CPU feature is impossible or too hard, KVM has to choose between not implementing the feature at all or introducing behavioral differences between virtual machines and bare metal systems. com> wrote: > > On Mon, Jun 17, 2019 at 07:24:44PM +0800, Wanpeng Li wrote: > > From: Wanpeng Li <wanpengli@tencent. 0: device is already attached x2apic: IRQ From: luferry <luferry@xxxxxxx> x2apic_eanbled() costs about 200 cycles when guest trigger halt pretty high, pi ops in hotpath Signed-off-by: luferry <luferry@xxxxxxx> [PATCH 09/11] KVM: x86: Treat x2APIC's ICR as a 64-bit register, not two 32-bit regs From: Sean Christopherson Date: Fri Feb 04 2022 - 16:42:51 EST Next message: Sean Christopherson: "[PATCH 06/11] KVM: x86: WARN if KVM emulates an IPI without clearing the BUSY flag" Jan 4, 2023 · I am using ubuntu 22. kiszka@web. 2 Interrupt Virtualization Tables with Guest Virtual APIC Enabled) states that when IOMMU AVC is enabled, certain commonly accessed data fields are not cached by IOMMU * kvm_apic_map. Jan 19, 2017 · I was running a KVM host with Intel(R) Xeon(R) CPU E3-1230 v2 (8 cores total). I did check bios and didn’t see any way to select that video device for primary. suthikulpanit@xxxxxxx> Jul 14, 2020 · flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch cpuid_fault invpcid_single QEMU KVM - GPU Passthrough with AMD APIC - Windows 10 - win10. This vulnerability may allow a guest virtual machine to directly access host x2APIC Model-Specific Registers (MSRs) when it resets its Advanced Programmable Interrupt Controller (APIC). 0. 000000 This is implementation of x2apic for KVM that I wrote a while ago. 50 monitor - type 'help' for more information (qemu) No errors this time, but the guest's eax=1 cpuid returns ecx 21 bit clear, no matter what I do. x2apic feature is in the kvm_default_props and automatically added to all CPU models when KVM is enabled. 7-rc1, since many deps were merged - fix etc/boot-cpus to account for -device provided cpus May 14, 2022 · KVM主要由两个LKM内核模块组成，第一个是kvm. Jun 30, 2009 · KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. conf: Hi Paolo, Would you help to review this patch, plz? Many thanks. Mar 28, 2020 · * Some of the technical info may be wrong as am not an expert which is why I try to include as much sources as I can. You have to use KVM (or a different emulator). It will trigger warning of "host doesn't support requested feature: CPUID. Apply the following patch to KVM and re-compile. [18] [19] Jun 26, 2018 · Here are some links that while not providing me with the solution, gave me some information to point me in the right direction. Paravirtualized KVM features are represented as CPU flags. echo "options kvm ignore_msrs=1" > /etc/modprobe. 096903] DMAR: Host address width 46 [ 0. 0 any x86 KVM VM will have x2apic automatically enabled, so there's no explicit need to opt in. ko，提供主要的虚拟化功能；第二个是kvm-intel. Unable to update APIC_TPR when x2APIC is enabled and -global kvm-pit. A recent update to the AMD I/O Virtualization Technology (IOMMU) Specification(2. In that, L1 guest could access L0's APIC register values via L2 guest, when 'virtualize x2APIC mode' is enabled. 9) $ qemu-system-x86_64 -cpu help Recognized CPUID flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 pn clflush ds acpi mmx fxsr sse sse2 ss ht tm ia64 pbe pni pclmulqdq dtes64 monitor ds-cpl vmx smx est tm2 ssse3 cid fma cx16 Sep 22, 2016 · Changes since v1: - rebase on top of 2. org> To: stable@vger. ---Best wishes Yi Wang > å 2019å7æ6æï01:08ïYi Wang <wang. g. 32-rc1), there's no reason for not enabling x2apic by default KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK must be enabled for x2APIC to work in logical mode or with more than 255 VCPUs. 401716] DMAR: IOMMU enabled [ 0. 000000] DMAR: DRHD base: 0x000000fbffc000 flags: 0x1 [ 0. d/kvm. 431653] DMAR: dmar0: reg_base_addr fbffd000 ver 1:0 cap Feb 19, 2021 · But if you still want it then you can place your changes in accel\kvm\kvm-all. KVM on ARM does this splitting lazily by default. There is an option to select primary video as “onboard” or “offboard” but I tried selecting that last night and whoopsie, had to clear cmos to get it to boot back into bios again - it froze at boot asking for me to connect the dsub to another input. All mentioned flags are already in Apr 9, 2019 · A flaw was found in the way KVM hypervisor handled x2APIC Machine Specific Rregister (MSR) access with nested(=1) virtualization enabled. 092612] DMAR: dmar0: reg_base_addr fbffd000 ver 1:0 cap Oct 9, 2020 · From: David Woodhouse <dwmw@amazon. How to resize kvm vm host. 431643] DMAR: Host address width 46 [ 0. From qemu. kernel. After some discussion it would seem the performance difference I found was due to something else - My gut feeling after testing and reviewing Jan 24, 2010 · Because of this advantage, KVM can and does emulate the x2APIC for older processors that do not physically support it, and this support is exposed from QEMU going back to Conroe and even for AMD Opteron G-series processors (neither of which natively support x2APIC). Jul 2, 2020 · Coccoc uses KVM (Kernel-based pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 sse4_1 sse4_2 x2apic popcnt hypervisor lahf_lm Oct 1, 2022 · Sean Christopherson (31): KVM: x86: Blindly get current x2APIC reg value on "nodecode write" traps KVM: x86: Purge "highest ISR" cache when updating APICv state KVM: SVM: Flush the "current" TLB when activating AVIC KVM: SVM: Process ICR on AVIC IPI delivery failure due to invalid target KVM: x86: Don't inhibit APICv/AVIC on xAPIC ID "change Jul 9, 2015 · As of qemu 2. Intel guest can enter x2apic cluster mode when interrupt remmaping is enabled in qemu, however, latest AMD EPYC still just supports xapic mode which can get great improvement by PV IPIs. 04 LTS Headless Server; Debian 9 - install KVM server headless server; Reset root password for Linux KVM VM; Clone existing KVM virtual machine images [PATCH] enable x2APIC without interrupt remapping under KVM Groups Add CPUID check for the x2APIC virtualization (x2AVIC) feature. 11+dfsg-1ubuntu7. 010958] ACPI: Reserving DMAR table memory at [mem 0x7a5c3130-0x7a5c3237] [ 0. 000000] DMAR: Host address width 46 [ 0. Jan 20, 2014 · Normally we try to keep the CPU model definitions as close as the real CPUs as possible, but x2apic can be emulated by KVM without host CPU support for x2apic, and it improves performance by reducing APIC access overhead. dd -enable-kvm -cpu host,+x2apic -monitor stdio QEMU 2. From: Lan Tianyu <tianyu. Dec 2, 2022 · 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. 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 the required mode. But userspace devices don't support x2apic which can't be enabled without the in-kernel irqchip. 40GHz x86 kvm64 Common KVM processor x86 qemu32 QEMU Virtual CPU version 1. ignore_msrs=1 video=efifb:off,vesafb:off pcie_acs_override=downstream,multifunction vfio_iommu Nov 19, 2024 · This entry is 3 of 10 in the Linux KVM Cloud Computing/VM Tutorial series. co. Intel SDM (10. 39 vbox. 3 x86 kvm32 Common 32-bit KVM processor x86 coreduo Genuine Intel(R) CPU T2600 @ 2. features and that`s my output: KVM: SVM: Adding support for configuring x2APIC MSRs interception KVM: SVM: Update AVIC settings when changing APIC mode KVM: SVM: Introduce helper functions to (de)activate AVIC and x2AVIC KVM: SVM: Do not throw warning when calling avic_vcpu_load on a running vcpu KVM: SVM: Do not inhibit APICv when x2APIC is present kvm/x86: Remove APICV Nov 12, 2021 · My work platform is on a virtual machine, so it does not support KVM. Biederman: "Re: [PATCH v5] enable x2APIC without interrupt remapping under KVM" Next in thread: Eric W. img Nov 1, 2024 · > KVM's xapic_state_test selftest has been fudging the bug since commit > 4b88b1a518b3 ("KVM: selftests: Enhance handling WRMSR ICR register in > x2APIC mode"), which essentially removed the testcase instead of fixing Sep 9, 2015 · The root cause has been found, need to configure KVM_DEVICE_ASSIGNMENT option to build kernel. wstppz ohsddc hmbzytb fkptyv mmmqh aflj gozn pzaujvle bqwpbv ykzk