[v3] xen/arm: Add Armv8-R64 MPU support to Xen - Part#1

[PATCH v3 09/52] xen/arm: use PA == VA for EARLY_UART_VIRTUAL_ADDRESS on MPU systems

Posted by Penny Zheng 2 years, 3 months ago

From: Wei Chen <wei.chen@arm.com>

There is no VMSA support on MPU systems, so we can not map early
UART to FIXMAP_CONSOLE. In stead, we can use PA == VA for early
UART on MPU systems.

Signed-off-by: Wei Chen <wei.chen@arm.com>
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v2:
1. New patch
---
v3:
1. fix comment
2. change CONFIG_ARM_V8R to !CONFIG_HAS_MMU
---
 xen/arch/arm/include/asm/early_printk.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/xen/arch/arm/include/asm/early_printk.h b/xen/arch/arm/include/asm/early_printk.h
index c5149b2976..ec5bcc343c 100644
--- a/xen/arch/arm/include/asm/early_printk.h
+++ b/xen/arch/arm/include/asm/early_printk.h
@@ -15,10 +15,22 @@
 
 #ifdef CONFIG_EARLY_PRINTK
 
+#ifndef CONFIG_HAS_MMU
+
+/*
+ * For MPU systems, there is no VMSA support in EL2, so we use VA == PA
+ * for EARLY_UART_VIRTUAL_ADDRESS.
+ */
+#define EARLY_UART_VIRTUAL_ADDRESS CONFIG_EARLY_UART_BASE_ADDRESS
+
+#else
+
 /* need to add the uart address offset in page to the fixmap address */
 #define EARLY_UART_VIRTUAL_ADDRESS \
     (FIXMAP_ADDR(FIXMAP_CONSOLE) + (CONFIG_EARLY_UART_BASE_ADDRESS & ~PAGE_MASK))
 
+#endif /* CONFIG_HAS_MMU */
+
 #endif /* !CONFIG_EARLY_PRINTK */
 
 #endif
-- 
2.25.1

Re: [PATCH v3 09/52] xen/arm: use PA == VA for EARLY_UART_VIRTUAL_ADDRESS on MPU systems

Posted by Julien Grall 2 years, 3 months ago

Hi Penny,

On 26/06/2023 04:34, Penny Zheng wrote:
> From: Wei Chen <wei.chen@arm.com>
> 
> There is no VMSA support on MPU systems, so we can not map early
> UART to FIXMAP_CONSOLE. In stead, we can use PA == VA for early
> UART on MPU systems.
> 
> Signed-off-by: Wei Chen <wei.chen@arm.com>
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>

Is this change necessary for the MMU split? If not, I will skip the 
review for now.

Cheers,

-- 
Julien Grall

Re: [PATCH v3 09/52] xen/arm: use PA == VA for EARLY_UART_VIRTUAL_ADDRESS on MPU systems

Posted by Penny Zheng 2 years, 3 months ago

Hi Julien

On 2023/7/5 03:25, Julien Grall wrote:
> Hi Penny,
> 
> On 26/06/2023 04:34, Penny Zheng wrote:
>> From: Wei Chen <wei.chen@arm.com>
>>
>> There is no VMSA support on MPU systems, so we can not map early
>> UART to FIXMAP_CONSOLE. In stead, we can use PA == VA for early
>> UART on MPU systems.
>>
>> Signed-off-by: Wei Chen <wei.chen@arm.com>
>> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> 
> Is this change necessary for the MMU split? If not, I will skip the 
> review for now.
> 

It is not necessary. I will not include it in next series focusing on 
MMU split.

> Cheers,
>