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Re: [PATCH v3 28/52] xen/mpu: plump virt/maddr conversion in MPU system
- To: Julien Grall <julien@xxxxxxx>, Ayan Kumar Halder <ayankuma@xxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Penny Zheng <penny.zheng@xxxxxxx>
- Date: Fri, 30 Jun 2023 10:40:06 +0800
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Wei Chen <wei.chen@xxxxxxx>
- Delivery-date: Fri, 30 Jun 2023 02:40:45 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Nodisclaimer: true
Hi,
On 2023/6/29 23:14, Julien Grall wrote:
Hi,
On 29/06/2023 15:44, Ayan Kumar Halder wrote:
On 29/06/2023 15:23, Andrew Cooper wrote:
On 29/06/2023 3:20 pm, Ayan Kumar Halder wrote:
On 26/06/2023 04:34, Penny Zheng wrote:
diff --git a/xen/arch/arm/include/asm/mm.h
b/xen/arch/arm/include/asm/mm.h
index eb520b49e3..ea4847c12b 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -292,6 +301,12 @@ static inline void *maddr_to_virt(paddr_t ma)
((ma & ma_top_mask) >> pfn_pdx_hole_shift)));
}
#endif
+#else /* CONFIG_HAS_MPU */
+static inline void *maddr_to_virt(paddr_t ma)
+{
+ return (void *)(unsigned long)ma;
Why do you need "(unsigned long)ma" ? Both "unsigned long" and
"paddr_t" are u64.
For when paddr_t really isn't u64.
Sorry, I am missing something
From
https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/arm/include/asm/types.h;h=fb6618ef247fe8e3abe472e50b4877e11cc8a96c;hb=refs/heads/staging
In CONFIG_ARM_64
typedef unsigned long u64;
typedef u64 paddr_t;
So, why do we need to typecast "paddr_t" to "unsigned long" as they
are the same ?
We may decide to restrict paddr_t to 32-bit in the future on Arm64.
Also, when CONFIG_PHYS_ADDR_T_32=n, paddr_t is 64-bit on 32-bit Xen. So
casting directly to (void *) is not possible. Although, this is not a
problem here because for the MPU on 32-bit, you would select
CONFIG_PHYS_ADDR_T_32.
On a side note, I agree with Andrew that we should switch to _p().
Sure. I'll switch to _p().
Cheers,
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