From: Marcelo Tosatti Date: Wed, 28 Nov 2012 01:29:03 +0000 (-0200) Subject: KVM: x86: require matched TSC offsets for master clock X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~27^2~22 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b48aa97e38206a84bf8485e7c553412274708ce5;p=pandora-kernel.git KVM: x86: require matched TSC offsets for master clock With master clock, a pvclock clock read calculates: ret = system_timestamp + [ (rdtsc + tsc_offset) - tsc_timestamp ] Where 'rdtsc' is the host TSC. system_timestamp and tsc_timestamp are unique, one tuple per VM: the "master clock". Given a host with synchronized TSCs, its obvious that guest TSC must be matched for the above to guarantee monotonicity. Allow master clock usage only if guest TSCs are synchronized. Signed-off-by: Marcelo Tosatti --- Reading git-diff-tree failed