hvf: RDTSCP capability not passed to guests
Host environment
- Operating system: macOS Monterey 12.3.1
- OS/kernel version: 21E258
- Architecture: x86_64
- QEMU flavor: qemu-system-x86_64
- QEMU version: 6.2.0, master
- QEMU command line:
./qemu-system-x86_64 -cpu host,+rdtscp -machine q35,accel=hvf -m 512 -cdrom ./alpine-standard-3.15.4-x86.iso
Emulated/Virtualized environment
- Operating system: Alpine 3.15.4
- OS/kernel version: 5.15.32-0-virt #1-Alpine SMP
- Architecture: x86_64
Description of problem
Steps to reproduce
-
Run: wget https://dl-cdn.alpinelinux.org/alpine/v3.15/releases/x86/alpine-standard-3.15.4-x86.iso ./qemu-system-x86_64 -cpu host,+rdtscp -machine q35,accel=hvf -m 512 -cdrom ./alpine-standard-3.15.4-x86.iso
-
login as "root"
-
type
cat /etc/cpuinfo | grep rdtscp
Expected result: cpu flag lines including rdtscp Actual result: empty, with:
warning: host doesn't support requested feature: CPUID.80000001H:EDX.rdtscp [bit 27]
Additional information
This patch apparently resolves the issue according to my tests:
https://lore.kernel.org/qemu-devel/20211101054836.21471-1-dirty@apple.com/