Re: [Xen-devel] [PATCH 24/27] xen/arm: page: Describe the layout of flags used to update page tables

2017-08-23 Thread Julien Grall 



On 08/23/2017 03:08 PM, Andre Przywara wrote:

Hi,

On 14/08/17 15:24, Julien Grall wrote:

Currently, the flags used to update page tables (i.e PAGE_HYPERVISOR_*)
only contains the memory attribute index. Follow-up patches will add
more information in it.

At the same time introduce PAGE_AI_MASK to get the memory attribute
index easily.

Signed-off-by: Julien Grall 


I wonder if that should be merged with the next patch, to explain the
reason for it. As it stands now it just applies a mask to some existing
call, which looks a bit suspicious.
But that's just a nit and the patch itself is fine, so:


Not really it just documents the current behavior rather than hiding 
what is going on.


Cheers,



Reviewed-by: Andre Przywara 

Cheers,
Andre.


---
  xen/arch/arm/mm.c  | 2 +-
  xen/include/asm-arm/page.h | 7 +++
  2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 411fe02842..cd7bcf7aca 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1021,7 +1021,7 @@ static int create_xen_entries(enum xenmap_operation op,
  }
  if ( op == RESERVE )
  break;
-pte = mfn_to_xen_entry(mfn, flags);
+pte = mfn_to_xen_entry(mfn, PAGE_AI_MASK(flags));
  pte.pt.table = 1;
  write_pte(entry, pte);
  break;
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index d9dac92e73..1bf8e9d012 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -63,6 +63,13 @@
  #define MAIR0VAL (MAIRVAL & 0x)
  #define MAIR1VAL (MAIRVAL >> 32)
  
+/*

+ * Layout of the flags used for updating the hypervisor page tables
+ *
+ * [0:2] Memory Attribute Index
+ */
+#define PAGE_AI_MASK(x) ((x) & 0x7U)
+
  #define PAGE_HYPERVISOR (MT_NORMAL)
  #define PAGE_HYPERVISOR_NOCACHE (MT_DEVICE_nGnRE)
  #define PAGE_HYPERVISOR_WC  (MT_NORMAL_NC)



--
Julien Grall

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Re: [Xen-devel] [PATCH 24/27] xen/arm: page: Describe the layout of flags used to update page tables

2017-08-23 Thread Andre Przywara 
Hi,

On 14/08/17 15:24, Julien Grall wrote:
> Currently, the flags used to update page tables (i.e PAGE_HYPERVISOR_*)
> only contains the memory attribute index. Follow-up patches will add
> more information in it.
> 
> At the same time introduce PAGE_AI_MASK to get the memory attribute
> index easily.
> 
> Signed-off-by: Julien Grall 

I wonder if that should be merged with the next patch, to explain the
reason for it. As it stands now it just applies a mask to some existing
call, which looks a bit suspicious.
But that's just a nit and the patch itself is fine, so:

Reviewed-by: Andre Przywara 

Cheers,
Andre.

> ---
>  xen/arch/arm/mm.c  | 2 +-
>  xen/include/asm-arm/page.h | 7 +++
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 411fe02842..cd7bcf7aca 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -1021,7 +1021,7 @@ static int create_xen_entries(enum xenmap_operation op,
>  }
>  if ( op == RESERVE )
>  break;
> -pte = mfn_to_xen_entry(mfn, flags);
> +pte = mfn_to_xen_entry(mfn, PAGE_AI_MASK(flags));
>  pte.pt.table = 1;
>  write_pte(entry, pte);
>  break;
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index d9dac92e73..1bf8e9d012 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -63,6 +63,13 @@
>  #define MAIR0VAL (MAIRVAL & 0x)
>  #define MAIR1VAL (MAIRVAL >> 32)
>  
> +/*
> + * Layout of the flags used for updating the hypervisor page tables
> + *
> + * [0:2] Memory Attribute Index
> + */
> +#define PAGE_AI_MASK(x) ((x) & 0x7U)
> +
>  #define PAGE_HYPERVISOR (MT_NORMAL)
>  #define PAGE_HYPERVISOR_NOCACHE (MT_DEVICE_nGnRE)
>  #define PAGE_HYPERVISOR_WC  (MT_NORMAL_NC)
> 

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[Xen-devel] [PATCH 24/27] xen/arm: page: Describe the layout of flags used to update page tables

2017-08-14 Thread Julien Grall 
Currently, the flags used to update page tables (i.e PAGE_HYPERVISOR_*)
only contains the memory attribute index. Follow-up patches will add
more information in it.

At the same time introduce PAGE_AI_MASK to get the memory attribute
index easily.

Signed-off-by: Julien Grall 
---
 xen/arch/arm/mm.c  | 2 +-
 xen/include/asm-arm/page.h | 7 +++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 411fe02842..cd7bcf7aca 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1021,7 +1021,7 @@ static int create_xen_entries(enum xenmap_operation op,
 }
 if ( op == RESERVE )
 break;
-pte = mfn_to_xen_entry(mfn, flags);
+pte = mfn_to_xen_entry(mfn, PAGE_AI_MASK(flags));
 pte.pt.table = 1;
 write_pte(entry, pte);
 break;
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index d9dac92e73..1bf8e9d012 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -63,6 +63,13 @@
 #define MAIR0VAL (MAIRVAL & 0x)
 #define MAIR1VAL (MAIRVAL >> 32)
 
+/*
+ * Layout of the flags used for updating the hypervisor page tables
+ *
+ * [0:2] Memory Attribute Index
+ */
+#define PAGE_AI_MASK(x) ((x) & 0x7U)
+
 #define PAGE_HYPERVISOR (MT_NORMAL)
 #define PAGE_HYPERVISOR_NOCACHE (MT_DEVICE_nGnRE)
 #define PAGE_HYPERVISOR_WC  (MT_NORMAL_NC)
-- 
2.11.0


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