Re: [PATCH 1/2] KVM: kvm_is_visible_gfn can be boolean

From: Amos Jianjun Kong
Date: Sat Nov 14 2015 - 05:07:57 EST


On Sat, Nov 14, 2015 at 11:21 AM, Yaowei Bai
<baiyaowei@xxxxxxxxxxxxxxxxxxxx> wrote:
> This patch makes kvm_is_visible_gfn return bool due to this particular
> function only using either one or zero as its return value.
>
> No functional change.
>
> Signed-off-by: Yaowei Bai <baiyaowei@xxxxxxxxxxxxxxxxxxxx>

Hi Yaowei,

> ---
> include/linux/kvm_host.h | 2 +-
> virt/kvm/kvm_main.c | 6 +++---
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 5706a21..4436539 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -623,7 +623,7 @@ int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
> int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
> struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
> -int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn);
> +bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn);
> unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn);
> void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 484079e..73cbb41 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1164,15 +1164,15 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn
> return __gfn_to_memslot(kvm_vcpu_memslots(vcpu), gfn);
> }
>
> -int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
> +bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
> {
> struct kvm_memory_slot *memslot = gfn_to_memslot(kvm, gfn);
>
> if (!memslot || memslot->id >= KVM_USER_MEM_SLOTS ||
> memslot->flags & KVM_MEMSLOT_INVALID)
> - return 0;
> + return false;
>
> - return 1;
> + return true;
> }
> EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);


kvm_is_visible_gfn() is also used in arch/powerpc/kvm/book3s_pr.c:

static int kvmppc_visible_gpa(struct kvm_vcpu *vcpu, gpa_t gpa)
{
......
if (unlikely(mp_pa) && unlikely((mp_pa & KVM_PAM) == (gpa & KVM_PAM))) {
return 1;
}

return kvm_is_visible_gfn(vcpu->kvm, gpa >> PAGE_SHIFT);
}

Do we still need to update that function?

Thanks, Amos
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