From: Avi Kivity Date: Mon, 7 Sep 2009 08:12:18 +0000 (+0300) Subject: KVM: x86 shared msr infrastructure X-Git-Tag: v2.6.33-rc1~387^2~20 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=18863bdd60f895f3b3ba16b15e8331aee781e8ec;p=pandora-kernel.git KVM: x86 shared msr infrastructure The various syscall-related MSRs are fairly expensive to switch. Currently we switch them on every vcpu preemption, which is far too often: - if we're switching to a kernel thread (idle task, threaded interrupt, kernel-mode virtio server (vhost-net), for example) and back, then there's no need to switch those MSRs since kernel threasd won't be exiting to userspace. - if we're switching to another guest running an identical OS, most likely those MSRs will have the same value, so there's little point in reloading them. - if we're running the same OS on the guest and host, the MSRs will have identical values and reloading is unnecessary. This patch uses the new user return notifiers to implement last-minute switching, and checks the msr values to avoid unnecessary reloading. Signed-off-by: Avi Kivity --- Reading git-diff-tree failed