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Message-ID: <96d1a959-95ab-4db0-8afb-baa0c614ac8b@amd.com> Date: Thu, 3 Apr 2025 17:35:46 +0100 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 5/5] xen/arm32: mpu: Stubs to build MPU for arm32 Content-Language: en-GB To: Julien Grall , Ayan Kumar Halder , xen-devel@lists.xenproject.org Cc: Stefano Stabellini , Bertrand Marquis , Michal Orzel , Volodymyr Babchuk References: <20250330180308.2551195-1-ayan.kumar.halder@amd.com> <20250330180308.2551195-6-ayan.kumar.halder@amd.com> <6a767fe1-2d77-4cd4-9726-498fbb27ce87@xen.org> From: Ayan Kumar Halder In-Reply-To: <6a767fe1-2d77-4cd4-9726-498fbb27ce87@xen.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: LO4P123CA0691.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:37b::19) To PH8PR12MB7326.namprd12.prod.outlook.com (2603:10b6:510:216::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR12MB7326:EE_|SN7PR12MB7105:EE_ X-MS-Office365-Filtering-Correlation-Id: 8515328c-99a9-4989-7cfe-08dd72cd9806 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024; 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New patch introduced in v3. >> 2. Should be applied on top of >> https://patchwork.kernel.org/project/xen-devel/cover/20250316192445.2376484-1-luca.fancellu@arm.com/ >> >> >>   xen/arch/arm/Kconfig             |  2 +- >>   xen/arch/arm/arm32/mpu/Makefile  |  2 ++ >>   xen/arch/arm/arm32/mpu/p2m.c     | 18 ++++++++++++++++++ >>   xen/arch/arm/arm32/mpu/smpboot.c | 23 +++++++++++++++++++++++ >>   xen/arch/arm/include/asm/mm.h    |  5 +++++ >>   5 files changed, 49 insertions(+), 1 deletion(-) >>   create mode 100644 xen/arch/arm/arm32/mpu/p2m.c >>   create mode 100644 xen/arch/arm/arm32/mpu/smpboot.c >> >> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig >> index 565f288331..a1dd942091 100644 >> --- a/xen/arch/arm/Kconfig >> +++ b/xen/arch/arm/Kconfig >> @@ -1,7 +1,7 @@ >>   config ARM_32 >>       def_bool y >>       depends on "$(ARCH)" = "arm32" >> -    select ARCH_MAP_DOMAIN_PAGE >> +    select ARCH_MAP_DOMAIN_PAGE if MMU > > If ARCH_MAP_DOMAIN_PAGE is not present, then the assumption is Xen > will be able to access all the memory. Is this what we want long term? > > If not, then I would consider providing stubs rather than disable > ARCH_MAP_DOMAIN_PAGE. I will provide the stubs. > >>     config ARM_64 >>       def_bool y >> diff --git a/xen/arch/arm/arm32/mpu/Makefile >> b/xen/arch/arm/arm32/mpu/Makefile >> index 3340058c08..38797f28af 100644 >> --- a/xen/arch/arm/arm32/mpu/Makefile >> +++ b/xen/arch/arm/arm32/mpu/Makefile >> @@ -1 +1,3 @@ >>   obj-y += head.o >> +obj-y += smpboot.o >> +obj-y += p2m.o >> diff --git a/xen/arch/arm/arm32/mpu/p2m.c b/xen/arch/arm/arm32/mpu/p2m.c >> new file mode 100644 >> index 0000000000..df8de5c7d8 >> --- /dev/null >> +++ b/xen/arch/arm/arm32/mpu/p2m.c >> @@ -0,0 +1,18 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> + >> +#include >> +#include >> + >> +void __init setup_virt_paging(void) >> +{ >> +    BUG_ON("unimplemented"); >> +} >> + >> +/* >> + * Local variables: >> + * mode: C >> + * c-file-style: "BSD" >> + * c-basic-offset: 4 >> + * indent-tabs-mode: nil >> + * End: >> + */ >> diff --git a/xen/arch/arm/arm32/mpu/smpboot.c >> b/xen/arch/arm/arm32/mpu/smpboot.c >> new file mode 100644 >> index 0000000000..3f3e54294e >> --- /dev/null >> +++ b/xen/arch/arm/arm32/mpu/smpboot.c >> @@ -0,0 +1,23 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> + >> +#include >> + >> +int prepare_secondary_mm(int cpu) >> +{ >> +    BUG_ON("unimplemented"); >> +    return -EINVAL; >> +} >> + >> +void update_boot_mapping(bool enable) >> +{ >> +    BUG_ON("unimplemented"); >> +} >> + >> +/* >> + * Local variables: >> + * mode: C >> + * c-file-style: "BSD" >> + * c-basic-offset: 4 >> + * indent-tabs-mode: nil >> + * End: >> + */ >> diff --git a/xen/arch/arm/include/asm/mm.h >> b/xen/arch/arm/include/asm/mm.h >> index fbffaccef4..a894e28ac9 100644 >> --- a/xen/arch/arm/include/asm/mm.h >> +++ b/xen/arch/arm/include/asm/mm.h >> @@ -171,12 +171,17 @@ struct page_info >>   #define PGC_need_scrub    PGC_allocated >>     #ifdef CONFIG_ARM_32 >> +#ifdef CONFIG_MPU >> +#define is_xen_heap_page(page) false >> +#define is_xen_heap_mfn(mfn) false > > Can you clarify whether this is the intended implementation? If not > then we can be use BUG_ON("unimplemented")? yes, we will use BUG_ON("unimplemented"). > > Also... > >> +#else >>   #define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page)) >>   #define is_xen_heap_mfn(mfn) ({                                 \ >>       unsigned long mfn_ = mfn_x(mfn);                            \ >>       (mfn_ >= mfn_x(directmap_mfn_start) &&                      \ >>        mfn_ < mfn_x(directmap_mfn_end));                          \ >>   }) >> +#endif > > ... is the implementation will be similar to is_xen_heap_page() for MMU? > >>   #else >>   #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap) >>   #define is_xen_heap_mfn(mfn) \ > - Ayan > Cheers, >