Re: [PATCH 2/4] KVM: Introduce hva_to_gfn() for kvm_handle_hva()

Takuya Yoshikawa
2012-06-15T21:49:42Z

On Fri, 15 Jun 2012 20:31:44 +0900
Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> wrote:

...

> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index d03eb6f..53716dd 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -767,15 +767,13 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
>
> slots = kvm_memslots(kvm);
> kvm_for_each_memslot(memslot, slots) {
> - unsigned long start = memslot->userspace_addr;
> - unsigned long end;
> + gfn_t gfn = hva_to_gfn(hva, memslot);
>
> - end = start + (memslot->npages << PAGE_SHIFT);
> - if (hva >= start && hva < end) {
> - gfn_t gfn_offset = (hva - start) >> PAGE_SHIFT;
> + if (gfn >= memslot->base_gfn &&
> + gfn < memslot->base_gfn + memslot->npages) {

Here
...

> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index a2f3969..ba57b3b 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -1199,14 +1199,10 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
> slots = kvm_memslots(kvm);
>
> kvm_for_each_memslot(memslot, slots) {
> - unsigned long start = memslot->userspace_addr;
> - unsigned long end;
> -
> - end = start + (memslot->npages << PAGE_SHIFT);
> - if (hva >= start && hva < end) {
> - gfn_t gfn_offset = (hva - start) >> PAGE_SHIFT;
> - gfn_t gfn = memslot->base_gfn + gfn_offset;
> + gfn_t gfn = hva_to_gfn(hva, memslot);
>
> + if (gfn >= memslot->base_gfn &&
> + gfn < memslot->base_gfn + memslot->npages) {

and here
...

> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 27ac8a4..92b2029 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -740,6 +740,13 @@ static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
> (base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
> }
>
> +static inline gfn_t hva_to_gfn(unsigned long hva, struct kvm_memory_slot *slot)
> +{
> + gfn_t gfn_offset = (hva - slot->userspace_addr) >> PAGE_SHIFT;
> +
> + return slot->base_gfn + gfn_offset;
> +}

Something wrong may happen when hva < slot->userspace_addr.

I will fix this after I get some feedback for other parts.

Takuya