Re: [PATCH] KVM: nVMX: fixes for preemption timer migration

Jim Mattson
2020-07-09T17:23:36Z

On Thu, Jul 9, 2020 at 10:15 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
> 2020-06-01) accidentally broke nVMX live migration from older version
> by changing the userspace ABI. Restore it and, while at it, ensure
> that vmx->nested.has_preemption_timer_deadline is always initialized
> according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.
>
> Cc: Makarand Sonare <makarandsonare@google.com>
> Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/include/uapi/asm/kvm.h | 5 +++--
> arch/x86/kvm/vmx/nested.c | 3 ++-
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 17c5a038f42d..0780f97c1850 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
> };
>
> struct kvm_vmx_nested_state_hdr {
> - __u32 flags;
> __u64 vmxon_pa;
> __u64 vmcs12_pa;
> - __u64 preemption_timer_deadline;
>
> struct {
> __u16 flags;
> } smm;
> +
> + __u32 flags;
> + __u64 preemption_timer_deadline;
> };
>
> struct kvm_svm_nested_state_data {
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index b26655104d4a..3fc2411edc92 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -6180,7 +6180,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
> vmx->nested.has_preemption_timer_deadline = true;
> vmx->nested.preemption_timer_deadline =
> kvm_state->hdr.vmx.preemption_timer_deadline;
> - }
> + } else
> + vmx->nested.has_preemption_timer_deadline = false;

Doesn't the coding standard require braces around the else clause?

Reviewed-by: Jim Mattson <jmattson@google.com>