[PATCH v2 0/2] Clean and invalidate dcache for boot pagetables during setup

[PATCH v2 0/2] Clean and invalidate dcache for boot pagetables during setup

[Oleksandr Tyshchenko]

Hello, all.

This small patch series are needed to avoid possible hangs during bringing up non-boot CPU.
This solution was suggested by Julien Grall and Ian Campbell.   

Discussion in Xen project Mailing List:
http://lists.xen.org/archives/html/xen-devel/2014-02/msg01575.html

The first patch introduces a new macro clean_and_invalidate_xen_dcache().
Unlike existing macro clean_xen_dcache() this macro performs clean and invalidate dcache.
The second patch replaces clean_xen_dcache() macro by a clean_and_invalidate_xen_dcache()
for boot pagetables after cleaning them.

This patch series was tested on DRA7 platform manufactured by TI.

v2:
 - modify flush_page_to_ram() to call clean_and_invalidate_xen_dcache_va_range() function
 - some changes related to coding-style 

Oleksandr Tyshchenko (2):
  xen/arm: Introduce clean_and_invalidate_xen_dcache() macro
  xen/arm: Clean and invalidate dcache for boot pagetables

 xen/arch/arm/mm.c          |   14 +++++---------
 xen/include/asm-arm/page.h |   26 ++++++++++++++++++++++++--
 2 files changed, 29 insertions(+), 11 deletions(-)

-- 
1.7.9.5

[PATCH v2 1/2] xen/arm: Introduce clean_and_invalidate_xen_dcache() macro

[Oleksandr Tyshchenko]

This macro is very similar to clean_xen_dcache(), but it performs
clean and invalidate dcache.

Also modify flush_page_to_ram() to call
clean_and_invalidate_xen_dcache_va_range() function.

Signed-off-by: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
CC: Ian Campbell <ian.campbell@citrix.com>
---
 xen/arch/arm/mm.c          |    8 ++------
 xen/include/asm-arm/page.h |   26 ++++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 308a798..544aa87 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -344,13 +344,9 @@ unsigned long domain_page_map_to_mfn(const void *ptr)
 
 void flush_page_to_ram(unsigned long mfn)
 {
-    void *p, *v = map_domain_page(mfn);
-
-    dsb();           /* So the CPU issues all writes to the range */
-    for ( p = v; p < v + PAGE_SIZE ; p += cacheline_bytes )
-        asm volatile (__clean_and_invalidate_xen_dcache_one(0) : : "r" (p));
-    dsb();           /* So we know the flushes happen before continuing */
+    void *v = map_domain_page(mfn);
 
+    clean_and_invalidate_xen_dcache_va_range(v, PAGE_SIZE);
     unmap_domain_page(v);
 }
 
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index e00be9e..dfac003 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -226,7 +226,7 @@ static inline lpae_t mfn_to_xen_entry(unsigned long mfn)
 /* Actual cacheline size on the boot CPU. */
 extern size_t cacheline_bytes;
 
-/* Function for flushing medium-sized areas.
+/* Functions for flushing medium-sized areas.
  * if 'range' is large enough we might want to use model-specific
  * full-cache flushes. */
 static inline void clean_xen_dcache_va_range(void *p, unsigned long size)
@@ -238,7 +238,17 @@ static inline void clean_xen_dcache_va_range(void *p, unsigned long size)
     dsb();           /* So we know the flushes happen before continuing */
 }
 
-/* Macro for flushing a single small item.  The predicate is always
+static inline void clean_and_invalidate_xen_dcache_va_range
+    (void *p, unsigned long size)
+{
+    void *end;
+    dsb();           /* So the CPU issues all writes to the range */
+    for ( end = p + size; p < end; p += cacheline_bytes )
+        asm volatile (__clean_and_invalidate_xen_dcache_one(0) : : "r" (p));
+    dsb();           /* So we know the flushes happen before continuing */
+}
+
+/* Macros for flushing a single small item.  The predicate is always
  * compile-time constant so this will compile down to 3 instructions in
  * the common case. */
 #define clean_xen_dcache(x) do {                                        \
@@ -253,6 +263,18 @@ static inline void clean_xen_dcache_va_range(void *p, unsigned long size)
             : : "r" (_p), "m" (*_p));                                   \
 } while (0)
 
+#define clean_and_invalidate_xen_dcache(x) do {                         \
+    typeof(x) *_p = &(x);                                               \
+    if ( sizeof(x) > MIN_CACHELINE_BYTES || sizeof(x) > alignof(x) )    \
+        clean_and_invalidate_xen_dcache_va_range(_p, sizeof(x));        \
+    else                                                                \
+        asm volatile (                                                  \
+            "dsb sy;"   /* Finish all earlier writes */                 \
+            __clean_and_invalidate_xen_dcache_one(0)                    \
+            "dsb sy;"   /* Finish flush before continuing */            \
+            : : "r" (_p), "m" (*_p));                                   \
+} while (0)
+
 /* Flush the dcache for an entire page. */
 void flush_page_to_ram(unsigned long mfn);
 
-- 
1.7.9.5

Re: [PATCH v2 1/2] xen/arm: Introduce clean_and_invalidate_xen_dcache() macro

[Julien Grall]

Hello Oleksandr,

On 03/11/2014 01:19 PM, Oleksandr Tyshchenko wrote:
> This macro is very similar to clean_xen_dcache(), but it performs
> clean and invalidate dcache.
> 
> Also modify flush_page_to_ram() to call
> clean_and_invalidate_xen_dcache_va_range() function.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
> Reviewed-by: Julien Grall <julien.grall@linaro.org>

Please remove this "Reviewed-by". I have only gave my "reviewed-by" on
patch #2 (see V1).

Regards,

-- 
Julien Grall

Re: [PATCH v2 1/2] xen/arm: Introduce clean_and_invalidate_xen_dcache() macro

[Oleksandr Tyshchenko]

On Tue, Mar 11, 2014 at 3:37 PM, Julien Grall <julien.grall@linaro.org> wrote:
> Hello Oleksandr,
>
> On 03/11/2014 01:19 PM, Oleksandr Tyshchenko wrote:
>> This macro is very similar to clean_xen_dcache(), but it performs
>> clean and invalidate dcache.
>>
>> Also modify flush_page_to_ram() to call
>> clean_and_invalidate_xen_dcache_va_range() function.
>>
>> Signed-off-by: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
>> Reviewed-by: Julien Grall <julien.grall@linaro.org>
>
> Please remove this "Reviewed-by". I have only gave my "reviewed-by" on
> patch #2 (see V1).
>
> Regards,
>
> --
> Julien Grall

Sorry, I will correct
-- 

Oleksandr Tyshchenko | Embedded Developer
GlobalLogic
www.globallogic.com

Re: [PATCH v2 1/2] xen/arm: Introduce clean_and_invalidate_xen_dcache() macro

[Ian Campbell]

On Wed, 2014-03-12 at 16:05 +0200, Oleksandr Tyshchenko wrote:
> On Tue, Mar 11, 2014 at 3:37 PM, Julien Grall <julien.grall@linaro.org> wrote:
> > Hello Oleksandr,
> >
> > On 03/11/2014 01:19 PM, Oleksandr Tyshchenko wrote:
> >> This macro is very similar to clean_xen_dcache(), but it performs
> >> clean and invalidate dcache.
> >>
> >> Also modify flush_page_to_ram() to call
> >> clean_and_invalidate_xen_dcache_va_range() function.
> >>
> >> Signed-off-by: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
> >> Reviewed-by: Julien Grall <julien.grall@linaro.org>
> >
> > Please remove this "Reviewed-by". I have only gave my "reviewed-by" on
> > patch #2 (see V1).

> Sorry, I will correct

I replaced it with my Ack and applied this and the second patch.

Thanks,
Ian.

Re: [PATCH v2 1/2] xen/arm: Introduce clean_and_invalidate_xen_dcache() macro

[Oleksandr Tyshchenko]

>
> I replaced it with my Ack and applied this and the second patch.
>
> Thanks,
> Ian.
>

Thank you
-- 

Oleksandr Tyshchenko | Embedded Developer
GlobalLogic
www.globallogic.com

[PATCH v2 2/2] xen/arm: Clean and invalidate dcache for boot pagetables

[Oleksandr Tyshchenko]

We need to invalidate dcache too after zeroing boot pagetables
to avoid unpredictable behavior which may take place after
non-boot CPUs enable their caches.

So, replace clean_xen_dcache() macro by a clean_and_invalidate_xen_dcache()
for boot pagetables.

Signed-off-by: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
CC: Ian Campbell <ian.campbell@citrix.com>
---
 xen/arch/arm/mm.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 544aa87..305879f 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -480,13 +480,13 @@ void __init setup_pagetables(unsigned long boot_phys_offset, paddr_t xen_paddr)
     /* Clear the copy of the boot pagetables. Each secondary CPU
      * rebuilds these itself (see head.S) */
     memset(boot_pgtable, 0x0, PAGE_SIZE);
-    clean_xen_dcache(boot_pgtable);
+    clean_and_invalidate_xen_dcache(boot_pgtable);
 #ifdef CONFIG_ARM_64
     memset(boot_first, 0x0, PAGE_SIZE);
-    clean_xen_dcache(boot_first);
+    clean_and_invalidate_xen_dcache(boot_first);
 #endif
     memset(boot_second, 0x0, PAGE_SIZE);
-    clean_xen_dcache(boot_second);
+    clean_and_invalidate_xen_dcache(boot_second);
 
     /* Break up the Xen mapping into 4k pages and protect them separately. */
     for ( i = 0; i < LPAE_ENTRIES; i++ )
-- 
1.7.9.5