Re: [PATCH v3 1/4] xen: arm: Add a new helper update_boot_mapping()

[Ayan Kumar Halder]

On 14/08/2024 13:50, Michal Orzel wrote:

Hi Ayan,

Hi Michal,

On 13/08/2024 19:13, Ayan Kumar Halder wrote:

update_boot_mapping() invokes update_identity_mapping() for the MMU specific
code.
Later when the MPU code is added, update_boot_mapping() would invoke the
equivalent.

The common code now invokes update_boot_mapping() instead of
update_identity_mapping(). So, that there is clear abstraction between the
common and MMU/MPU specific logic.

This is in continuation to commit
f661a20aa880: "Extract MMU-specific MM code".

update_identity_mapping() is now marked as static as it is called within
xen/arch/arm/arm64/mmu/mm.c only. Also, updated the prototype to
update_boot_mapping() which is now invoked from other files.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.hal...@amd.com>
---
Changes from :-

v1 - 1. Introduced update_boot_mapping() which invokes
update_identity_mapping() in MMU specific code.

v2 - 1. Make update_identity_mapping() static and update the prototype.

  xen/arch/arm/arm64/mmu/mm.c         | 7 ++++++-
  xen/arch/arm/arm64/smpboot.c        | 6 +++---
  xen/arch/arm/include/asm/arm64/mm.h | 2 +-
  3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/arm64/mmu/mm.c b/xen/arch/arm/arm64/mmu/mm.c
index 293acb67e0..1afbbeda5a 100644
--- a/xen/arch/arm/arm64/mmu/mm.c
+++ b/xen/arch/arm/arm64/mmu/mm.c
@@ -111,7 +111,7 @@ void __init arch_setup_page_tables(void)
      prepare_runtime_identity_mapping();
  }

-void update_identity_mapping(bool enable)

+static void update_identity_mapping(bool enable)
  {
      paddr_t id_addr = virt_to_maddr(_start);
      int rc;
@@ -125,6 +125,11 @@ void update_identity_mapping(bool enable)
      BUG_ON(rc);
  }

+void update_boot_mapping(bool enable)

+{
+    update_identity_mapping(enable);
+}
+
  extern void switch_ttbr_id(uint64_t ttbr);

typedef void (switch_ttbr_fn)(uint64_t ttbr);

diff --git a/xen/arch/arm/arm64/smpboot.c b/xen/arch/arm/arm64/smpboot.c
index a225fae64d..789f352ab6 100644
--- a/xen/arch/arm/arm64/smpboot.c
+++ b/xen/arch/arm/arm64/smpboot.c
@@ -112,18 +112,18 @@ int arch_cpu_up(int cpu)
      if ( !smp_enable_ops[cpu].prepare_cpu )
          return -ENODEV;

- update_identity_mapping(true);

+    update_boot_mapping(true);

rc = smp_enable_ops[cpu].prepare_cpu(cpu);

      if ( rc )
-        update_identity_mapping(false);
+        update_boot_mapping(false);

return rc;

  }

void arch_cpu_up_finish(void)

  {
-    update_identity_mapping(false);
+    update_boot_mapping(false);
  }

/*

diff --git a/xen/arch/arm/include/asm/arm64/mm.h 
b/xen/arch/arm/include/asm/arm64/mm.h
index e0bd23a6ed..ac8d1f5c78 100644
--- a/xen/arch/arm/include/asm/arm64/mm.h
+++ b/xen/arch/arm/include/asm/arm64/mm.h
@@ -21,7 +21,7 @@ void arch_setup_page_tables(void);
   * Note that nested call (e.g. enable=true, enable=true) is not
   * supported.
   */
-void update_identity_mapping(bool enable);
+void update_boot_mapping(bool enable);

The whole point of adding a wrapper was to avoid ambiguity \wrt identity 
mapping and MPU.
You changed the name of a function but left the comment which is pretty MMU 
specific. I think
it should be moved to update_identity_mapping.

Yes, you are correct. I will move the comment before

static void update_identity_mapping(bool enable)

{...}

Apart from that:
Reviewed-by: Michal Orzel <michal.or...@amd.com>

I will keep your R-b

- Ayan