https://bugzilla.kernel.org/show_bug.cgi?id=200877 Bug ID: 200877 Summary: Low 2D graphics performance with Windows 10 (1803) VGA passthrough VM using "Spectre" protection Product: Virtualization Version: unspecified Kernel Version: 4.15.0-32-generic x86_64 Hardware: Intel OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: kvm Assignee: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx Reporter: hs7762@xxxxxxxxx Regression: No Created attachment 278013 --> https://bugzilla.kernel.org/attachment.cgi?id=278013&action=edit Red graph - Windows 10 bare metal; blue graph - Windows 10 VM with Spectre protection enabled; yellow graph - Windows 10 VM with spectre protection disabled After upgrading Windows 10 Pro VM to version 1803, or possibly after applying the March security updates from Microsoft, the VM would show low 2D graphics performance (sluggishness in 2D applications and low Passmark results). Turning off Spectre vulnerability protection in Windows remedies the issue. Expected behavior: kvm hypervisor to expose firmware capabilities of host to guest OS - see https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/CVE-2017-5715-and-hyper-v-vms Background: Starting in March or April Microsoft began to push driver updates in their updates / security updates. See https://support.microsoft.com/en-us/help/4073757/protect-your-windows-devices-against-spectre-meltdown One update concerns the Intel microcode - see https://support.microsoft.com/en-us/help/4100347. It is activated by default within Windows. Once the updates are applied within the Windows guest, 2D graphics performance drops significantly. Other performance benchmarks are not affected. A bare metal Windows installation does not display a performance loss after the update. Hardware: 6 core Intel Core i7-3930K (-MT-MCP-) Host OS: Linux Mint 19/Ubuntu 18.04 Kernel: 4.15.0-32-generic x86_64 Qemu: QEMU emulator version 2.11.1 Intel microcode (host): 0x714 dmesg | grep microcode [ 0.000000] microcode: microcode updated early to revision 0x714, date = 2018-05-08 [ 2.810683] microcode: sig=0x206d7, pf=0x4, revision=0x714 [ 2.813340] microcode: Microcode Update Driver: v2.2. Note: I manually updated the Intel microcode on the host from 0x713 to 0x714. However, both microcode versions produce the same result in the Windows guest. Guest OS: Windows 10 Pro 64 bit, release 1803 -- You are receiving this mail because: You are watching the assignee of the bug.
