Re: [PATCH v7 09/17] KVM: s390: pv: clear the state without memset

Janosch Frank
2022-02-07T10:18:49Z

On 2/4/22 16:53, Claudio Imbrenda wrote:
> Do not use memset to clean the whole struct kvm_s390_pv; instead,
> explicitly clear the fields that need to be cleared.
>
> Upcoming patches will introduce new fields in the struct kvm_s390_pv
> that will not need to be cleared.
>
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
> arch/s390/kvm/pv.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 9e900ce7387d..f1e812a45acb 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -16,6 +16,15 @@
> #include <linux/sched/mm.h>
> #include "kvm-s390.h"
>
> +static void kvm_s390_clear_pv_state(struct kvm *kvm)
> +{
> + kvm->arch.pv.handle = 0;
> + kvm->arch.pv.guest_len = 0;
> + kvm->arch.pv.stor_base = 0;
> + kvm->arch.pv.stor_var = NULL;
> + kvm->arch.pv.handle = 0;

You really want to make sure the handle is zero :)

With this fixed:
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> +}
> +
> int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc)
> {
> int cc;
> @@ -110,7 +119,7 @@ static void kvm_s390_pv_dealloc_vm(struct kvm *kvm)
> vfree(kvm->arch.pv.stor_var);
> free_pages(kvm->arch.pv.stor_base,
> get_order(uv_info.guest_base_stor_len));
> - memset(&kvm->arch.pv, 0, sizeof(kvm->arch.pv));
> + kvm_s390_clear_pv_state(kvm);
> }
>
> static int kvm_s390_pv_alloc_vm(struct kvm *kvm)
>