On 12/23/2014 10:14 AM, Paolo Bonzini wrote:
On 23/12/2014 16:14, Boris Ostrovsky wrote:
+ do {
+ version = pvti->version;
+
+ /* This is also a read barrier, so we'll read version first. */
+ rdtsc_barrier();
+ tsc = __native_read_tsc();
This will cause VMEXIT on Xen with TSC_MODE_ALWAYS_EMULATE which is
used, for example, after guest migrated (unless HW is capable of scaling
TSC rate).
So does the __pvclock_read_cycles this is replacing (via
pvclock_get_nsec_offset).
Right, I didn't notice that.
-boris
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