From e2b6c1712e08bc5feafb44fdc65ab81ef2630b4b Mon Sep 17 00:00:00 2001 From: Denis Plotnikov Date: Mon, 29 May 2017 13:49:04 +0300 Subject: [PATCH] kvmclock: update system_time_msr address forcibly Do an update of system_time_msr address every time before reading the value of tsc_timestamp from guest's kvmclock page. There is no other code paths which ensure that qemu has an up-to-date value of system_time_msr. So, force this update on guest's tsc_timestamp reading. This bug causes effect on those nested setups which turn off TPR access interception for L2 guests and that access being intercepted by L0 doesn't show up in L1. Linux bootstrap initiate kvmclock before APIC initializing causing TPR access. That's why on L1 guests, having TPR interception turned on for L2, the effect of the bug is not revealed. This patch fixes this problem by making sure it knows the correct system_time_msr address every time it is needed. Signed-off-by: Denis Plotnikov Message-Id: <1496054944-25623-1-git-send-email-dplotnikov@virtuozzo.com> Signed-off-by: Paolo Bonzini --- hw/i386/kvm/clock.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 13eca374cd..363d1b5743 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -19,6 +19,7 @@ #include "qemu/host-utils.h" #include "sysemu/sysemu.h" #include "sysemu/kvm.h" +#include "sysemu/hw_accel.h" #include "kvm_i386.h" #include "hw/sysbus.h" #include "hw/kvm/clock.h" @@ -69,6 +70,8 @@ static uint64_t kvmclock_current_nsec(KVMClockState *s) uint64_t nsec_hi; uint64_t nsec; + cpu_synchronize_state(cpu); + if (!(env->system_time_msr & 1ULL)) { /* KVM clock not active */ return 0;