On Thu, Sep 26, 2013 at 07:47:33PM +0200, Paolo Bonzini wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Il 26/09/2013 19:19, Jan Kiszka ha scritto: > > On 2013-09-26 17:04, Paolo Bonzini wrote: > >> Il 16/09/2013 10:11, Arthur Chunqi Li ha scritto: > >>> This patch contains the following two changes: > >>> 1. Fix the bug in nested preemption timer support. If vmexit L2->L0 > >>> with some reasons not emulated by L1, preemption timer value should > >>> be save in such exits. > >>> 2. Add support of "Save VMX-preemption timer value" VM-Exit controls > >>> to nVMX. > >>> > >>> With this patch, nested VMX preemption timer features are fully > >>> supported. > >>> > >>> Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx> > >>> --- > >>> ChangeLog to v4: > >>> Format changes and remove a flag in nested_vmx. > >>> arch/x86/include/uapi/asm/msr-index.h | 1 + > >>> arch/x86/kvm/vmx.c | 44 +++++++++++++++++++++++++++++++-- > >>> 2 files changed, 43 insertions(+), 2 deletions(-) > >> > >> Hi all, > >> > >> the test fails for me if the preemption timer value is set to a value > >> that is above ~2000 (which means ~65000 TSC cycles on this machine). > >> The preemption timer seems to count faster than what is expected, for > >> example only up to 4 million cycles if you set it to one million. > >> So, I am leaving the patch out of kvm/queue for now, until I can > >> test it on more processors. > > > > So this behaviour is a regression of this patch (and your own version as > > well)? > > Without this patch Arthur's preemption timer test doesn't work at all. > Have you ruled out test bugs? I see things like: + int i, j; ... + // Consume enough time to let L2->L0->L2 occurs + for(i = 0; i < 100000; i++) + for (j = 0; j < 10000; j++); which can be optimized out. Or use of rdtsc() which can be problematic if host tsc is not synchronised. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
