Patchwork [v3,11/21] kvm: x86: Reset paravirtual MSRs

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Submitter Jan Kiszka
Date Jan. 4, 2011, 8:32 a.m.
Message ID <f3323139e2fdb7009f7c5320416c3b937545feec.1294129949.git.jan.kiszka@web.de>
Download mbox | patch
Permalink /patch/77423/
State New
Headers show

Comments

Jan Kiszka - Jan. 4, 2011, 8:32 a.m.
From: Jan Kiszka <jan.kiszka@siemens.com>

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 <jan.kiszka@siemens.com>
CC: Glauber Costa <glommer@redhat.com>
---
 target-i386/kvm.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
Glauber Costa - Jan. 4, 2011, 11:06 a.m.
On Tue, 2011-01-04 at 09:32 +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> 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 <jan.kiszka@siemens.com>
> CC: Glauber Costa <glommer@redhat.com>

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);

Patch

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);