On Wed, Jul 06, 2016 at 04:29:35PM +0200, Paolo Bonzini wrote: > Can you test this in the meanwhile: > > git clone git://git.kernel.org/pub/scm/virt/kvm/kvm-unit-tests.git > cd kvm-unit-tests > ./configure > make > ./x86/run x86/tsc.flat -cpu kvm64,+rdtscp > > On Intel I see: > > enabling apic > rdtsc latency 18 > rdtsc after wrtsc(0): 727124155 > rdtsc after wrtsc(100000000000): 100000001759 > PASS: Test RDTSCP 0 > PASS: Test RDTSCP 10 > PASS: Test RDTSCP 256 > SUMMARY: 3 tests Ok, found it: I need to start the guest with "+rdtscp", see below. Which begs the question: can we readd CPUID_EXT2_RDTSCP to the Opteron_* models as in the second diff here: https://lkml.kernel.org/r/20160706124438.GB7300@xxxxxxx ? Or are we still afraid of "host doesn't support requested feature" messages from: 33b5e8c03ae7 ("target-i386: Disable rdtscp on Opteron_G* CPU models") ? $ ./x86/run x86/tsc.flat -cpu kvm64,+rdtscp qemu-system-x86_64 -enable-kvm -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -kernel x86/tsc.flat -cpu kvm64,+rdtscp enabling apic rdtsc latency 68 rdtsc after wrtsc(0): 988590164 rdtsc after wrtsc(100000000000): 100000002807 PASS: Test RDTSCP 0 PASS: Test RDTSCP 10 PASS: Test RDTSCP 256 SUMMARY: 3 tests latest qemu: $ QEMU=/root/src/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64 ./x86/run x86/tsc.flat -cpu kvm64,+rdtscp /root/src/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -kernel x86/tsc.flat -cpu kvm64,+rdtscp enabling apic rdtsc latency 69 rdtsc after wrtsc(0): 715310314 rdtsc after wrtsc(100000000000): 100000002434 PASS: Test RDTSCP 0 PASS: Test RDTSCP 10 PASS: Test RDTSCP 256 SUMMARY: 3 tests guest booted *without* "+rdtscp": taskset -c 3 ./rdtscp aux1: 0x0 aux2: 0x0 p1: 284683839780, p2: 284684080314, 240534 with "+rdtscp": $ taskset -c 3 ./rdtscp aux1: 0x3 aux2: 0x3 p1: 168907589830, p2: 168907856068, 266238 $ taskset -c 2 ./rdtscp aux1: 0x2 aux2: 0x2 p1: 176251144121, p2: 176251427089, 282968 Ok, all good. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html