From 54750f2cf042c42b4223d67b1bd20138464bde0e Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Tue, 20 Jan 2015 15:54:52 -0200 Subject: [PATCH] KVM: x86: workaround SuSE's 2.6.16 pvclock vs masterclock issue SuSE's 2.6.16 kernel fails to boot if the delta between tsc_timestamp and rdtsc is larger than a given threshold: * If we get more than the below threshold into the future, we rerequest * the real time from the host again which has only little offset then * that we need to adjust using the TSC. * * For now that threshold is 1/5th of a jiffie. That should be good * enough accuracy for completely broken systems, but also give us swing * to not call out to the host all the time. */ #define PVCLOCK_DELTA_MAX ((1000000000ULL / HZ) / 5) Disable masterclock support (which increases said delta) in case the boot vcpu does not use MSR_KVM_SYSTEM_TIME_NEW. Upstreams kernels which support pvclock vsyscalls (and therefore make use of PVCLOCK_STABLE_BIT) use MSR_KVM_SYSTEM_TIME_NEW. Signed-off-by: Marcelo Tosatti Signed-off-by: Paolo Bonzini --- Reading git-format-patch failed