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Date: Wed, 19 Dec 2007 16:53:08 +0200 From: Avi Kivity <avi@...ranet.com> To: Ingo Molnar <mingo@...e.hu> CC: Avi Kivity <avi@...ranet.com>, kvm-devel <kvm-devel@...ts.sourceforge.net>, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [kvm-devel] Guest kernel hangs in smp kvm for older kernels prior to tsc sync cleanup Ingo Molnar wrote: > * Avi Kivity <avi@...ranet.com> wrote: > > >> Avi Kivity wrote: >> >>> Testing shows wrmsr and rdtsc function normally. >>> >>> I'll try pinning the vcpus to cpus and see if that helps. >>> >>> >> It does. >> > > do we let the guest read the physical CPU's TSC? That would be trouble. > > vmx (and svm) allow us to add an offset to the physical tsc. We set it on startup to -tsc (so that an rdtsc on boot would return 0), and massage it on vcpu migration so that guest rdtsc is monotonic. The net effect is that tsc on a vcpu can experience large forward jumps and changes in rate, but no negative jumps. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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