All of lore.kernel.org
 help / color / mirror / Atom feed
From: Fuad Tabba <tabba@google.com>
To: Quentin Perret <qperret@google.com>
Cc: maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com,
	suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	ardb@kernel.org, qwandor@google.com, dbrazdil@google.com,
	kernel-team@android.com
Subject: Re: [PATCH v3 13/21] KVM: arm64: Expose host stage-2 manipulation helpers
Date: Mon, 2 Aug 2021 13:13:20 +0200	[thread overview]
Message-ID: <CA+EHjTxTaPc=bt_kyXf0TE85v5eyHnq0o3KQ3Pd6+kOwmm5oMw@mail.gmail.com> (raw)
In-Reply-To: <20210729132818.4091769-14-qperret@google.com>

Hi Quentin,

On Thu, Jul 29, 2021 at 3:28 PM Quentin Perret <qperret@google.com> wrote:
>
> We will need to manipulate the host stage-2 page-table from outside
> mem_protect.c soon. Introduce two functions allowing this, and make
> them usable to users of mem_protect.h.
>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 ++
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 17 ++++++++++++++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> index ae355bfd8c01..47c2a0c51612 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> @@ -49,6 +49,8 @@ extern struct host_kvm host_kvm;
>  int __pkvm_prot_finalize(void);
>  int __pkvm_mark_hyp(phys_addr_t start, phys_addr_t end);
>
> +int host_stage2_idmap_locked(u64 start, u64 end, enum kvm_pgtable_prot prot);
> +int host_stage2_set_owner_locked(u64 start, u64 end, u8 owner_id);
>  int kvm_host_prepare_stage2(void *pgt_pool_base);
>  void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index 70c57d2c3024..a7f6134789e0 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -272,6 +272,21 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
>         return 0;
>  }
>
> +int host_stage2_idmap_locked(u64 start, u64 end, enum kvm_pgtable_prot prot)
> +{
> +       hyp_assert_lock_held(&host_kvm.lock);
> +
> +       return host_stage2_try(__host_stage2_idmap, start, end, prot);
> +}
> +
> +int host_stage2_set_owner_locked(u64 start, u64 end, u8 owner_id)
> +{
> +       hyp_assert_lock_held(&host_kvm.lock);
> +
> +       return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
> +                              start, end - start, &host_s2_pool, owner_id);
> +}

This is a potential issue elsewhere as well, but all functions in
kvm_pgtable.h, including kvm_pgtable_stage2_set_owner, specify an
address range via address and size. The two you have introduced here
take a start and an end. I'm not sure if making these two consistent
with the ones in kvm_pgtable.h would be good, or would just complicate
things in other places.

Thanks,
/fuad

>  static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
>  {
>         /*
> @@ -309,7 +324,7 @@ static int host_stage2_idmap(u64 addr)
>         if (ret)
>                 goto unlock;
>
> -       ret = host_stage2_try(__host_stage2_idmap, range.start, range.end, prot);
> +       ret = host_stage2_idmap_locked(range.start, range.end, prot);
>  unlock:
>         hyp_spin_unlock(&host_kvm.lock);
>
> --
> 2.32.0.432.gabb21c7263-goog
>

WARNING: multiple messages have this Message-ID
From: Fuad Tabba <tabba@google.com>
To: Quentin Perret <qperret@google.com>
Cc: kernel-team@android.com, qwandor@google.com, maz@kernel.org,
	linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
	will@kernel.org, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 13/21] KVM: arm64: Expose host stage-2 manipulation helpers
Date: Mon, 2 Aug 2021 13:13:20 +0200	[thread overview]
Message-ID: <CA+EHjTxTaPc=bt_kyXf0TE85v5eyHnq0o3KQ3Pd6+kOwmm5oMw@mail.gmail.com> (raw)
In-Reply-To: <20210729132818.4091769-14-qperret@google.com>

Hi Quentin,

On Thu, Jul 29, 2021 at 3:28 PM Quentin Perret <qperret@google.com> wrote:
>
> We will need to manipulate the host stage-2 page-table from outside
> mem_protect.c soon. Introduce two functions allowing this, and make
> them usable to users of mem_protect.h.
>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 ++
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 17 ++++++++++++++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> index ae355bfd8c01..47c2a0c51612 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> @@ -49,6 +49,8 @@ extern struct host_kvm host_kvm;
>  int __pkvm_prot_finalize(void);
>  int __pkvm_mark_hyp(phys_addr_t start, phys_addr_t end);
>
> +int host_stage2_idmap_locked(u64 start, u64 end, enum kvm_pgtable_prot prot);
> +int host_stage2_set_owner_locked(u64 start, u64 end, u8 owner_id);
>  int kvm_host_prepare_stage2(void *pgt_pool_base);
>  void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index 70c57d2c3024..a7f6134789e0 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -272,6 +272,21 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
>         return 0;
>  }
>
> +int host_stage2_idmap_locked(u64 start, u64 end, enum kvm_pgtable_prot prot)
> +{
> +       hyp_assert_lock_held(&host_kvm.lock);
> +
> +       return host_stage2_try(__host_stage2_idmap, start, end, prot);
> +}
> +
> +int host_stage2_set_owner_locked(u64 start, u64 end, u8 owner_id)
> +{
> +       hyp_assert_lock_held(&host_kvm.lock);
> +
> +       return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
> +                              start, end - start, &host_s2_pool, owner_id);
> +}

This is a potential issue elsewhere as well, but all functions in
kvm_pgtable.h, including kvm_pgtable_stage2_set_owner, specify an
address range via address and size. The two you have introduced here
take a start and an end. I'm not sure if making these two consistent
with the ones in kvm_pgtable.h would be good, or would just complicate
things in other places.

Thanks,
/fuad

>  static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
>  {
>         /*
> @@ -309,7 +324,7 @@ static int host_stage2_idmap(u64 addr)
>         if (ret)
>                 goto unlock;
>
> -       ret = host_stage2_try(__host_stage2_idmap, range.start, range.end, prot);
> +       ret = host_stage2_idmap_locked(range.start, range.end, prot);
>  unlock:
>         hyp_spin_unlock(&host_kvm.lock);
>
> --
> 2.32.0.432.gabb21c7263-goog
>
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID
From: Fuad Tabba <tabba@google.com>
To: Quentin Perret <qperret@google.com>
Cc: maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com,
	 suzuki.poulose@arm.com, catalin.marinas@arm.com,
	will@kernel.org,  linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu,  linux-kernel@vger.kernel.org,
	ardb@kernel.org, qwandor@google.com,  dbrazdil@google.com,
	kernel-team@android.com
Subject: Re: [PATCH v3 13/21] KVM: arm64: Expose host stage-2 manipulation helpers
Date: Mon, 2 Aug 2021 13:13:20 +0200	[thread overview]
Message-ID: <CA+EHjTxTaPc=bt_kyXf0TE85v5eyHnq0o3KQ3Pd6+kOwmm5oMw@mail.gmail.com> (raw)
In-Reply-To: <20210729132818.4091769-14-qperret@google.com>

Hi Quentin,

On Thu, Jul 29, 2021 at 3:28 PM Quentin Perret <qperret@google.com> wrote:
>
> We will need to manipulate the host stage-2 page-table from outside
> mem_protect.c soon. Introduce two functions allowing this, and make
> them usable to users of mem_protect.h.
>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 ++
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 17 ++++++++++++++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> index ae355bfd8c01..47c2a0c51612 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> @@ -49,6 +49,8 @@ extern struct host_kvm host_kvm;
>  int __pkvm_prot_finalize(void);
>  int __pkvm_mark_hyp(phys_addr_t start, phys_addr_t end);
>
> +int host_stage2_idmap_locked(u64 start, u64 end, enum kvm_pgtable_prot prot);
> +int host_stage2_set_owner_locked(u64 start, u64 end, u8 owner_id);
>  int kvm_host_prepare_stage2(void *pgt_pool_base);
>  void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index 70c57d2c3024..a7f6134789e0 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -272,6 +272,21 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
>         return 0;
>  }
>
> +int host_stage2_idmap_locked(u64 start, u64 end, enum kvm_pgtable_prot prot)
> +{
> +       hyp_assert_lock_held(&host_kvm.lock);
> +
> +       return host_stage2_try(__host_stage2_idmap, start, end, prot);
> +}
> +
> +int host_stage2_set_owner_locked(u64 start, u64 end, u8 owner_id)
> +{
> +       hyp_assert_lock_held(&host_kvm.lock);
> +
> +       return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
> +                              start, end - start, &host_s2_pool, owner_id);
> +}

This is a potential issue elsewhere as well, but all functions in
kvm_pgtable.h, including kvm_pgtable_stage2_set_owner, specify an
address range via address and size. The two you have introduced here
take a start and an end. I'm not sure if making these two consistent
with the ones in kvm_pgtable.h would be good, or would just complicate
things in other places.

Thanks,
/fuad

>  static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
>  {
>         /*
> @@ -309,7 +324,7 @@ static int host_stage2_idmap(u64 addr)
>         if (ret)
>                 goto unlock;
>
> -       ret = host_stage2_try(__host_stage2_idmap, range.start, range.end, prot);
> +       ret = host_stage2_idmap_locked(range.start, range.end, prot);
>  unlock:
>         hyp_spin_unlock(&host_kvm.lock);
>
> --
> 2.32.0.432.gabb21c7263-goog
>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-08-02 11:14 UTC|newest]

Thread overview: 135+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 13:27 [PATCH v3 00/21] Track shared pages at EL2 in protected mode Quentin Perret
2021-07-29 13:27 ` Quentin Perret
2021-07-29 13:27 ` Quentin Perret
2021-07-29 13:27 ` [PATCH v3 01/21] KVM: arm64: Add hyp_spin_is_locked() for basic locking assertions at EL2 Quentin Perret
2021-07-29 13:27   ` Quentin Perret
2021-07-29 13:27   ` Quentin Perret
2021-07-29 13:27 ` [PATCH v3 02/21] KVM: arm64: Introduce hyp_assert_lock_held() Quentin Perret
2021-07-29 13:27   ` Quentin Perret
2021-07-29 13:27   ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 03/21] KVM: arm64: Provide the host_stage2_try() helper macro Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02  9:36   ` Fuad Tabba
2021-08-02  9:36     ` Fuad Tabba
2021-08-02  9:36     ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 04/21] KVM: arm64: Introduce helper to retrieve a PTE and its level Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 05/21] KVM: arm64: Expose page-table helpers Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 06/21] KVM: arm64: Optimize host memory aborts Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02  9:37   ` Fuad Tabba
2021-08-02  9:37     ` Fuad Tabba
2021-08-02  9:37     ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 07/21] KVM: arm64: Rename KVM_PTE_LEAF_ATTR_S2_IGNORED Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02  9:37   ` Fuad Tabba
2021-08-02  9:37     ` Fuad Tabba
2021-08-02  9:37     ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 08/21] KVM: arm64: Don't overwrite software bits with owner id Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02  9:38   ` Fuad Tabba
2021-08-02  9:38     ` Fuad Tabba
2021-08-02  9:38     ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 09/21] KVM: arm64: Tolerate re-creating hyp mappings to set software bits Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02  9:50   ` Fuad Tabba
2021-08-02  9:50     ` Fuad Tabba
2021-08-02  9:50     ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 10/21] KVM: arm64: Enable forcing page-level stage-2 mappings Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02  9:49   ` Fuad Tabba
2021-08-02  9:49     ` Fuad Tabba
2021-08-02  9:49     ` Fuad Tabba
2021-08-03 10:13     ` Quentin Perret
2021-08-03 10:13       ` Quentin Perret
2021-08-03 10:13       ` Quentin Perret
2021-08-03 10:43       ` Fuad Tabba
2021-08-03 10:43         ` Fuad Tabba
2021-08-03 10:43         ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 11/21] KVM: arm64: Allow populating software bits Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 12/21] KVM: arm64: Add helpers to tag shared pages in SW bits Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02 10:30   ` Fuad Tabba
2021-08-02 10:30     ` Fuad Tabba
2021-08-02 10:30     ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 13/21] KVM: arm64: Expose host stage-2 manipulation helpers Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02 11:13   ` Fuad Tabba [this message]
2021-08-02 11:13     ` Fuad Tabba
2021-08-02 11:13     ` Fuad Tabba
2021-08-03 10:20     ` Quentin Perret
2021-08-03 10:20       ` Quentin Perret
2021-08-03 10:20       ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 14/21] KVM: arm64: Expose pkvm_hyp_id Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 15/21] KVM: arm64: Introduce addr_is_memory() Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02 14:52   ` Fuad Tabba
2021-08-02 14:52     ` Fuad Tabba
2021-08-02 14:52     ` Fuad Tabba
2021-08-03 10:23     ` Quentin Perret
2021-08-03 10:23       ` Quentin Perret
2021-08-03 10:23       ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 16/21] KVM: arm64: Enable retrieving protections attributes of PTEs Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-02 14:52   ` Fuad Tabba
2021-08-02 14:52     ` Fuad Tabba
2021-08-02 14:52     ` Fuad Tabba
2021-08-03 10:24     ` Quentin Perret
2021-08-03 10:24       ` Quentin Perret
2021-08-03 10:24       ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 17/21] KVM: arm64: Mark host bss and rodata section as shared Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-03  5:02   ` Fuad Tabba
2021-08-03  5:02     ` Fuad Tabba
2021-08-03  5:02     ` Fuad Tabba
2021-08-03 10:34     ` Quentin Perret
2021-08-03 10:34       ` Quentin Perret
2021-08-03 10:34       ` Quentin Perret
2021-08-03 10:54       ` Fuad Tabba
2021-08-03 10:54         ` Fuad Tabba
2021-08-03 10:54         ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 18/21] KVM: arm64: Remove __pkvm_mark_hyp Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 19/21] KVM: arm64: Refactor protected nVHE stage-1 locking Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-03  5:31   ` Fuad Tabba
2021-08-03  5:31     ` Fuad Tabba
2021-08-03  5:31     ` Fuad Tabba
2021-08-03 10:37     ` Quentin Perret
2021-08-03 10:37       ` Quentin Perret
2021-08-03 10:37       ` Quentin Perret
2021-08-03 10:51       ` Fuad Tabba
2021-08-03 10:51         ` Fuad Tabba
2021-08-03 10:51         ` Fuad Tabba
2021-07-29 13:28 ` [PATCH v3 20/21] KVM: arm64: Restrict EL2 stage-1 changes in protected mode Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-08-03  8:22   ` Fuad Tabba
2021-08-03  8:22     ` Fuad Tabba
2021-08-03  8:22     ` Fuad Tabba
2021-08-03 10:43     ` Quentin Perret
2021-08-03 10:43       ` Quentin Perret
2021-08-03 10:43       ` Quentin Perret
2021-07-29 13:28 ` [PATCH v3 21/21] KVM: arm64: Make __pkvm_create_mappings static Quentin Perret
2021-07-29 13:28   ` Quentin Perret
2021-07-29 13:28   ` Quentin Perret

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CA+EHjTxTaPc=bt_kyXf0TE85v5eyHnq0o3KQ3Pd6+kOwmm5oMw@mail.gmail.com' \
    --to=tabba@google.com \
    --cc=alexandru.elisei@arm.com \
    --cc=ardb@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=dbrazdil@google.com \
    --cc=james.morse@arm.com \
    --cc=kernel-team@android.com \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=maz@kernel.org \
    --cc=qperret@google.com \
    --cc=qwandor@google.com \
    --cc=suzuki.poulose@arm.com \
    --cc=will@kernel.org \
    --subject='Re: [PATCH v3 13/21] KVM: arm64: Expose host stage-2 manipulation helpers' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.