Spectre_v1:Mitigation: usercopy/swapgs barriers and _user pointer sanitization Mds:Vulnerable: Clear CPU buffers attempted, no microcode SMT Host state unknown For example, let’s check the content of /sys/devices/system/cpu/vulnerabilities $ cd /sys/devices/system/cpu/vulnerabilities Here you can find out which features are exposed by each QEMU CPU model.Īt this point, it is also quite sensible to check which security mitigations are enabled and which are left vulnerable inside the guest OS. Once you have selected a base QEMU CPU model, you need to check if it satisfies your restrictions. Application Development Guide: Capability information.Driver capabilities XML format: Host capabilities.More info about how to obtain information about the capabilities of the virtualization host via the libvirt toolkit can be found here: According to the official documentation, the best QEMU model we’d have to choose in order to fit the specs of this heterogeneous datacenter would be Haswell-IBRS. This way you’ll make sure you are using the optimum model compatible with all of them while -and this is important -preserving the ability to live migrate VMs.įor example, imagine you have these three different CPU models: Skylake-Client-IBRS, Broadwell-noTSX-IBRS and Haswell-IBRS. Once you have your server specs, follow QEMU docs to select the best QEMU model supported by all your hosts. In that case, just repeat the process described above to find out which QEMU CPU models fits your hardware specs. However, this might not always be an option. You may want to group servers by CPU model in different OpenNebula clusters and then use the virtual CPU model closest to the hypervisor model. Note that the CPU model is r etrieved automatically during the host monitoring process and stored in KVM_CPU_MODEL □ If all your hosts have the same CPU, you can use this CPU model straightaway. You can see below the output when executed on a laptop: īy checking /host/cpu/model we can get the closest QEMU CPU model that fits the hardware of our host, in this case Broadwell-noTSX-IBRS. To do so, we can use the virsh -c qemu:///system capabilities command. The first step is always to find the closest QEMU CPU model that fits our hardware. In this post, I’d like to share my approach for selecting a CPU model for KVM x86 hosts, and some tips on how to deal with the possible restrictions you might face during that process. There are many factors that can limit our options, like security or performance restrictions, or even the hardware you are using in your data center. This can make QEMU difficult to use at first, but this provides flexibility in creating exactly the virtual machine that you want.Sometimes it can be hard to choose a CPU model for VMs. QEMU uses command line options to define everything. Unlike PC emulator systems like VMware or VirtualBox, you need to "build" your virtual system by instructing QEMU to add each component of the virtual machine. $ qemu-img create image.img 200M Run QEMU To create an image file that's about 200MB, type this: To initialize a file that you can use as a virtual C: drive, use the qemu-img command. Under QEMU, virtual drives are image files. Other media, including other hard drives or CD-ROM drives, are assigned D:, E:, and so on. A: and B: are the first and second floppy disk drives, and C: is the first hard drive. In DOS, just as in Windows, drives are represented as letters. You'll need a place to install the legacy system inside QEMU, and for that you'll need a virtual C: drive.
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