[Qemu-devel] Re: [PATCH v3 11/21] kvm: x86: Reset paravirtual MSRs

[Glauber Costa]

On Tue, 2011-01-04 at 09:32 +0100, Jan Kiszka wrote:
> From: Jan Kiszka <address@hidden>
> 
> Make sure to write the cleared MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
> and MSR_KVM_ASYNC_PF_EN to the kernel state so that a freshly booted
> guest cannot be disturbed by old values.
> 
> Signed-off-by: Jan Kiszka <address@hidden>
> CC: Glauber Costa <address@hidden>

looks good.

>  target-i386/kvm.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index d8f26bf..8267655 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -845,6 +845,13 @@ static int kvm_put_msrs(CPUState *env, int level)
>          if (smp_cpus == 1 || env->tsc != 0) {
>              kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc);
>          }
> +    }
> +    /*
> +     * The following paravirtual MSRs have side effects on the guest or are
> +     * too heavy for normal writeback. Limit them to reset or full state
> +     * updates.
> +     */
> +    if (level >= KVM_PUT_RESET_STATE) {
>          kvm_msr_entry_set(&msrs[n++], MSR_KVM_SYSTEM_TIME,
>                            env->system_time_msr);
>          kvm_msr_entry_set(&msrs[n++], MSR_KVM_WALL_CLOCK, 
> env->wall_clock_msr);