[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v1 2/4] xen/arm: mpu: Define Xen start address for MPU systems
On 28/08/2024 15:49, Julien Grall wrote: Hi, Hi Julien, On 23/08/2024 17:31, Ayan Kumar Halder wrote:From: Wei Chen <wei.chen@xxxxxxx> On Armv8-A, Xen has a fixed virtual start address (link address too) for all Armv8-A platforms. In an MMU based system, Xen can map its loaded address to this virtual start address. So, on Armv8-A platforms, the Xen start address does not need to be configurable. But on Armv8-R platforms, there is no MMU to map loaded address to a fixed virtual address and different platforms will have very different address space layout. So Xen cannot use a fixed physical address on MPU based system and need to have it configurable. So in this patch, we reuse the existing arm/platforms to store Armv8-R platforms' parameters. And `XEN_START_ADDRESS` is one kind of MPU based platform's parameters. So we define default `XEN_START_ADDRESS` in the MPU specific header file.This seems a left-over from as previous work? Yes, this needs to be removed. We also introduce one Kconfig option for users to override the default Xen start address of selected platform, if they think the default address doesn't suit their scenarios. For this Kconfig option, we use an unaligned address "0xffffffff" as the default value to indicate that users haven't used a customized Xen start address. Signed-off-by: Wei Chen <wei.chen@xxxxxxx> Signed-off-by: Jiamei.Xie <jiamei.xie@xxxxxxx> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx> --- xen/arch/arm/Kconfig | 11 +++++++++++ xen/arch/arm/include/asm/mpu/layout.h | 25 +++++++++++++++++++++++++ 2 files changed, 36 insertions(+) create mode 100644 xen/arch/arm/include/asm/mpu/layout.h diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index 686948cefd..d722ca690c 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -23,6 +23,17 @@ config ARCH_DEFCONFIG default "arch/arm/configs/arm32_defconfig" if ARM_32 default "arch/arm/configs/arm64_defconfig" if ARM_64 +config XEN_START_ADDRESS+ hex "Xen start address: keep default to use platform defined address"+ default 0xFFFFFFFF + depends on MPU + help+ This option is allowed to set customized address at which Xen will be+ linked on MPU systems.I don't quite understand what you mean by "allowed". I will rephrase this as ... "Used to set customized address at which which Xen will be linked on MPU systems. This address must be aligned to a page size. 0xFFFFFFFF is used as the default value to indicate that user hasn't customized this address." > This address must be aligned to a page size.> + Use 0xFFFFFFFF as the default value to indicate that user hasn't+ customized this address, and Xen use use the default value that has+ been defined in platform files.At least in this patch, there is no default set. Instead you will throw an error. Ack. See above. + menu "Architecture Features" choicediff --git a/xen/arch/arm/include/asm/mpu/layout.h b/xen/arch/arm/include/asm/mpu/layout.hnew file mode 100644 index 0000000000..82a74b8b5b --- /dev/null +++ b/xen/arch/arm/include/asm/mpu/layout.h @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0-onlyCoding style: /* SPDX-... */ Ack +/* + * config_mpu.h: A Linux-style configuration list for Arm MPU systems,> + * only can be included by config.h+ */I don't understand how this description match the content below. Also, shouldn't you include it from xen/config.h? My bad. This description is incorrect. I will remove the description as it is not needed at this point in time. + +#ifndef __ARM_CONFIG_MPU_H__ +#define __ARM_CONFIG_MPU_H__This doesn't match the name of the file. __ARM_MPU_LAYOUT_H__ + + +#define XEN_START_ADDRESS CONFIG_XEN_START_ADDRESS + +/*+ * All MPU platforms need to provide a XEN_START_ADDRESS for linker. This+ * address indicates where Xen image will be loaded and run from. This + * address must be aligned to a PAGE_SIZE. + */ +#if (XEN_START_ADDRESS % PAGE_SIZE) != 0 +#error "XEN_START_ADDRESS must be aligned to PAGE_SIZE" +#endif + +#define XEN_VIRT_START _AT(paddr_t, XEN_START_ADDRESS) + +#endif /* __ARM_CONFIG_MPU_H__ */ +Cheers, - Ayan
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