Re: [PATCH 6/6] arm/mpu: Map domain page in AArch64 MPU systems

["Orzel, Michal" <michal.orzel@xxxxxxx>]

On 28/11/2025 10:58, Harry Ramsey wrote:
> From: Penny Zheng <Penny.Zheng@xxxxxxx>
> 
> In MPU systems, we implement map_domain_page()/unmap_domain_page()
> through mapping the domain page with a MPU region on demand.
What prevents you from implementing the remaining few helpers?

~Michal

> 
> Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
> Signed-off-by: Harry Ramsey <harry.ramsey@xxxxxxx>
> ---
>  xen/arch/arm/Kconfig           |  1 +
>  xen/arch/arm/mpu/Makefile      |  1 +
>  xen/arch/arm/mpu/domain-page.c | 53 ++++++++++++++++++++++++++++++++++
>  3 files changed, 55 insertions(+)
>  create mode 100644 xen/arch/arm/mpu/domain-page.c
> 
> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> index a5c111e08e..dac9a16c28 100644
> --- a/xen/arch/arm/Kconfig
> +++ b/xen/arch/arm/Kconfig
> @@ -91,6 +91,7 @@ config MMU
>  
>  config MPU
>       bool "MPU" if UNSUPPORTED
> +     select ARCH_MAP_DOMAIN_PAGE if ARM_64
>       select ARM_SECURE_STATE if ARM_64
>       select STATIC_MEMORY
>       help
> diff --git a/xen/arch/arm/mpu/Makefile b/xen/arch/arm/mpu/Makefile
> index 4963c8b550..940297af3f 100644
> --- a/xen/arch/arm/mpu/Makefile
> +++ b/xen/arch/arm/mpu/Makefile
> @@ -1,5 +1,6 @@
>  obj-$(CONFIG_ARM_32) += arm32/
>  obj-$(CONFIG_ARM_64) += arm64/
> +obj-$(CONFIG_ARM_64) += domain-page.o
>  obj-y += mm.o
>  obj-y += p2m.o
>  obj-y += setup.init.o
> diff --git a/xen/arch/arm/mpu/domain-page.c b/xen/arch/arm/mpu/domain-page.c
> new file mode 100644
> index 0000000000..9248053ff5
> --- /dev/null
> +++ b/xen/arch/arm/mpu/domain-page.c
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/bug.h>
> +#include <xen/domain_page.h>
> +#include <xen/mm.h>
> +#include <xen/mm-frame.h>
> +#include <xen/types.h>
> +
> +void *map_domain_page_global(mfn_t mfn)
> +{
> +    BUG_ON("unimplemented");
> +    return NULL;
> +}
> +
> +/* Map a page of domheap memory */
> +void *map_domain_page(mfn_t mfn)
> +{
> +    paddr_t pa = mfn_to_maddr(mfn);
> +
> +    if ( map_pages_to_xen((unsigned long)pa, mfn, 1, PAGE_HYPERVISOR_RW) )
> +        return NULL;
> +
> +    return maddr_to_virt(pa);
> +}
> +
> +/* Release a mapping taken with map_domain_page() */
> +void unmap_domain_page(const void *ptr)
> +{
> +    paddr_t base = virt_to_maddr(ptr);
> +
> +    if ( destroy_entire_xen_mapping(base) )
> +        panic("Failed to unmap domain page\n");
> +}
> +
> +mfn_t domain_page_map_to_mfn(const void *ptr)
> +{
> +    BUG_ON("unimplemented");
> +    return INVALID_MFN;
> +}
> +
> +void unmap_domain_page_global(const void *va)
> +{
> +    BUG_ON("unimplemented");
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */