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From:   Fuad Tabba <tabba@google.com>
Date:   Wed, 1 Nov 2023 12:46:02 +0000
Message-ID: <CA+EHjTy5tmgGmVNGTX4a2Engb+r1AQizsMxwb8xqOi1f9+VQLA@mail.gmail.com>
Subject: Re: [PATCH v13 01/35] KVM: Tweak kvm_hva_range and hva_handler_t to
 allow reusing for gfn ranges
To:     Sean Christopherson <seanjc@google.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>, Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Huacai Chen <chenhuacai@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Anup Patel <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>, kvm@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Xiaoyao Li <xiaoyao.li@intel.com>,
        Xu Yilun <yilun.xu@intel.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
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        David Matlack <dmatlack@google.com>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Isaku Yamahata <isaku.yamahata@intel.com>,
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        Maciej Szmigiero <mail@maciej.szmigiero.name>,
        David Hildenbrand <david@redhat.com>,
        Quentin Perret <qperret@google.com>,
        Michael Roth <michael.roth@amd.com>,
        Wang <wei.w.wang@intel.com>,
        Liam Merwick <liam.merwick@oracle.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
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On Fri, Oct 27, 2023 at 7:22=E2=80=AFPM Sean Christopherson <seanjc@google.=
com> wrote:
>
> Rework and rename "struct kvm_hva_range" into "kvm_mmu_notifier_range" so
> that the structure can be used to handle notifications that operate on gf=
n
> context, i.e. that aren't tied to a host virtual address.  Rename the
> handler typedef too (arguably it should always have been gfn_handler_t).
>
> Practically speaking, this is a nop for 64-bit kernels as the only
> meaningful change is to store start+end as u64s instead of unsigned longs=
.
>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>

Cheers,
/fuad


>  virt/kvm/kvm_main.c | 34 +++++++++++++++++++---------------
>  1 file changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 486800a7024b..0524933856d4 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -541,18 +541,22 @@ static inline struct kvm *mmu_notifier_to_kvm(struc=
t mmu_notifier *mn)
>         return container_of(mn, struct kvm, mmu_notifier);
>  }
>
> -typedef bool (*hva_handler_t)(struct kvm *kvm, struct kvm_gfn_range *ran=
ge);
> +typedef bool (*gfn_handler_t)(struct kvm *kvm, struct kvm_gfn_range *ran=
ge);
>
>  typedef void (*on_lock_fn_t)(struct kvm *kvm, unsigned long start,
>                              unsigned long end);
>
>  typedef void (*on_unlock_fn_t)(struct kvm *kvm);
>
> -struct kvm_hva_range {
> -       unsigned long start;
> -       unsigned long end;
> +struct kvm_mmu_notifier_range {
> +       /*
> +        * 64-bit addresses, as KVM notifiers can operate on host virtual
> +        * addresses (unsigned long) and guest physical addresses (64-bit=
).
> +        */
> +       u64 start;
> +       u64 end;
>         union kvm_mmu_notifier_arg arg;
> -       hva_handler_t handler;
> +       gfn_handler_t handler;
>         on_lock_fn_t on_lock;
>         on_unlock_fn_t on_unlock;
>         bool flush_on_ret;
> @@ -581,7 +585,7 @@ static const union kvm_mmu_notifier_arg KVM_MMU_NOTIF=
IER_NO_ARG;
>              node =3D interval_tree_iter_next(node, start, last))      \
>
>  static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
> -                                                 const struct kvm_hva_ra=
nge *range)
> +                                                 const struct kvm_mmu_no=
tifier_range *range)
>  {
>         bool ret =3D false, locked =3D false;
>         struct kvm_gfn_range gfn_range;
> @@ -608,9 +612,9 @@ static __always_inline int __kvm_handle_hva_range(str=
uct kvm *kvm,
>                         unsigned long hva_start, hva_end;
>
>                         slot =3D container_of(node, struct kvm_memory_slo=
t, hva_node[slots->node_idx]);
> -                       hva_start =3D max(range->start, slot->userspace_a=
ddr);
> -                       hva_end =3D min(range->end, slot->userspace_addr =
+
> -                                                 (slot->npages << PAGE_S=
HIFT));
> +                       hva_start =3D max_t(unsigned long, range->start, =
slot->userspace_addr);
> +                       hva_end =3D min_t(unsigned long, range->end,
> +                                       slot->userspace_addr + (slot->npa=
ges << PAGE_SHIFT));
>
>                         /*
>                          * To optimize for the likely case where the addr=
ess
> @@ -660,10 +664,10 @@ static __always_inline int kvm_handle_hva_range(str=
uct mmu_notifier *mn,
>                                                 unsigned long start,
>                                                 unsigned long end,
>                                                 union kvm_mmu_notifier_ar=
g arg,
> -                                               hva_handler_t handler)
> +                                               gfn_handler_t handler)
>  {
>         struct kvm *kvm =3D mmu_notifier_to_kvm(mn);
> -       const struct kvm_hva_range range =3D {
> +       const struct kvm_mmu_notifier_range range =3D {
>                 .start          =3D start,
>                 .end            =3D end,
>                 .arg            =3D arg,
> @@ -680,10 +684,10 @@ static __always_inline int kvm_handle_hva_range(str=
uct mmu_notifier *mn,
>  static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_noti=
fier *mn,
>                                                          unsigned long st=
art,
>                                                          unsigned long en=
d,
> -                                                        hva_handler_t ha=
ndler)
> +                                                        gfn_handler_t ha=
ndler)
>  {
>         struct kvm *kvm =3D mmu_notifier_to_kvm(mn);
> -       const struct kvm_hva_range range =3D {
> +       const struct kvm_mmu_notifier_range range =3D {
>                 .start          =3D start,
>                 .end            =3D end,
>                 .handler        =3D handler,
> @@ -771,7 +775,7 @@ static int kvm_mmu_notifier_invalidate_range_start(st=
ruct mmu_notifier *mn,
>                                         const struct mmu_notifier_range *=
range)
>  {
>         struct kvm *kvm =3D mmu_notifier_to_kvm(mn);
> -       const struct kvm_hva_range hva_range =3D {
> +       const struct kvm_mmu_notifier_range hva_range =3D {
>                 .start          =3D range->start,
>                 .end            =3D range->end,
>                 .handler        =3D kvm_unmap_gfn_range,
> @@ -835,7 +839,7 @@ static void kvm_mmu_notifier_invalidate_range_end(str=
uct mmu_notifier *mn,
>                                         const struct mmu_notifier_range *=
range)
>  {
>         struct kvm *kvm =3D mmu_notifier_to_kvm(mn);
> -       const struct kvm_hva_range hva_range =3D {
> +       const struct kvm_mmu_notifier_range hva_range =3D {
>                 .start          =3D range->start,
>                 .end            =3D range->end,
>                 .handler        =3D (void *)kvm_null_fn,
> --
> 2.42.0.820.g83a721a137-goog
>