linux-kernel - Re: [PATCH RESEND] kvm: make kvm_vcpu_(un)map dependency on CONFIG_HAS

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Date:   Mon, 20 May 2019 15:45:29 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Michal Kubecek <mkubecek@...e.cz>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krcmar <rkrcmar@...hat.com>,
        KarimAllah Ahmed <karahmed@...zon.de>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] kvm: make kvm_vcpu_(un)map dependency on
 CONFIG_HAS_IOMEM explicit

On Mon, May 20, 2019 at 9:44 AM Michal Kubecek <mkubecek@...e.cz> wrote:
>
> Recently introduced functions kvm_vcpu_map() and kvm_vcpu_unmap() call
> memremap() and memunmap() which are only available if HAS_IOMEM is enabled
> but this dependency is not explicit, so that the build fails with HAS_IOMEM
> disabled.
>
> As both function are only used on x86 where HAS_IOMEM is always enabled,
> the easiest fix seems to be to only provide them when HAS_IOMEM is enabled.
>
> Fixes: e45adf665a53 ("KVM: Introduce a new guest mapping API")
> Signed-off-by: Michal Kubecek <mkubecek@...e.cz>

Hi Michal,

I see the same build issue on arm64 and as CONFIG_HAS_IOMEM is set
there this patch has no effect on solving that. Instead I had to
include linux/io.h in kvm_main.c to make it compile.

Regards,
Bjorn

> ---
>  include/linux/kvm_host.h | 6 +++++-
>  virt/kvm/kvm_main.c      | 2 ++
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 79fa4426509c..371d68fef5e1 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -759,9 +759,13 @@ struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu);
>  struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn);
>  kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
>  kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
> +
> +#ifdef CONFIG_HAS_IOMEM
>  int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
> -struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
>  void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
> +#endif
> +
> +struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
>  unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
>  unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
>  int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset,
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f0d13d9d125d..4a2c813e75d6 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1743,6 +1743,7 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
>  }
>  EXPORT_SYMBOL_GPL(gfn_to_page);
>
> +#ifdef CONFIG_HAS_IOMEM
>  static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
>                          struct kvm_host_map *map)
>  {
> @@ -1806,6 +1807,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
>         map->page = NULL;
>  }
>  EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
> +#endif /* CONFIG_HAS_IOMEM */
>
>  struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)
>  {
> --
> 2.21.0
>