| Message ID | 20240918175102.223076-3-ayan.kumar.halder@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Enable early bootup of AArch64 MPU systems | expand |
Hi Ayan, On 18/09/2024 19:51, Ayan Kumar Halder wrote: > From: Wei Chen <wei.chen@arm.com> > > 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, we introduce a Kconfig option for users to set the start address. The start > address needs to be aligned to 4KB. We have a check for this alignment. It would suggest to add some explanation why you want the start address to be 4KB aligned. > > In case if the user forgets to set the start address, then 0xffffffff is used > as default. This is to trigger the error (on alignment check) and thereby prompt > user to set the start address. > > Also updated config.h so that it includes mpu/layout.h when CONFIG_MPU is > defined. > > Signed-off-by: Wei Chen <wei.chen@arm.com> > Signed-off-by: Jiamei.Xie <jiamei.xie@arm.com> > Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com> > --- > Changes from :- > > v1 - 1. Fixed some of the coding style issues. > 2. Reworded the help message. > 3. Updated the commit message. > > xen/arch/arm/Kconfig | 10 ++++++++++ > xen/arch/arm/include/asm/config.h | 4 +++- > xen/arch/arm/include/asm/mpu/layout.h | 27 +++++++++++++++++++++++++++ Looking at this patch again, I don't see any modification in xen.lds.S. Is it intended? > 3 files changed, 40 insertions(+), 1 deletion(-) > create mode 100644 xen/arch/arm/include/asm/mpu/layout.h > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig > index e881f5ba57..ab3ef005a6 100644 > --- a/xen/arch/arm/Kconfig > +++ b/xen/arch/arm/Kconfig > @@ -23,6 +23,16 @@ 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 > + Used to set customized address at which which Xen will be linked on MPU > + systems. Must be aligned to 4KB. > + 0xFFFFFFFF is used as default value to indicate that user has not > + customized this address. > + > menu "Architecture Features" > > choice > diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h > index a2e22b659d..0a51142efd 100644 > --- a/xen/arch/arm/include/asm/config.h > +++ b/xen/arch/arm/include/asm/config.h > @@ -69,8 +69,10 @@ > #include <xen/const.h> > #include <xen/page-size.h> > > -#ifdef CONFIG_MMU > +#if defined(CONFIG_MMU) > #include <asm/mmu/layout.h> > +#elif defined(CONFIG_MPU) > +#include <asm/mpu/layout.h> > #else > # error "Unknown memory management layout" > #endif > diff --git a/xen/arch/arm/include/asm/mpu/layout.h b/xen/arch/arm/include/asm/mpu/layout.h > new file mode 100644 > index 0000000000..f9a5be2d6b > --- /dev/null > +++ b/xen/arch/arm/include/asm/mpu/layout.h > @@ -0,0 +1,27 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > + > +#ifndef __ARM_MPU_LAYOUT_H__ > +#define __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. Strictly speaking, this doesn't match the Kconfig. AFAIU, we still said the internal code may continue to rely on PAGE_SIZE for the time being. But I think we would want to have a BUILD_BUG_ON(PAGE_SIZE != SZ_4K) to catch any value change. > + */ > +#if (XEN_START_ADDRESS % PAGE_SIZE) != 0 > +#error "XEN_START_ADDRESS must be aligned to PAGE_SIZE" In the error message, you want to mention 4KB. Cheers,
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index e881f5ba57..ab3ef005a6 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -23,6 +23,16 @@ 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 + Used to set customized address at which which Xen will be linked on MPU + systems. Must be aligned to 4KB. + 0xFFFFFFFF is used as default value to indicate that user has not + customized this address. + menu "Architecture Features" choice diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h index a2e22b659d..0a51142efd 100644 --- a/xen/arch/arm/include/asm/config.h +++ b/xen/arch/arm/include/asm/config.h @@ -69,8 +69,10 @@ #include <xen/const.h> #include <xen/page-size.h> -#ifdef CONFIG_MMU +#if defined(CONFIG_MMU) #include <asm/mmu/layout.h> +#elif defined(CONFIG_MPU) +#include <asm/mpu/layout.h> #else # error "Unknown memory management layout" #endif diff --git a/xen/arch/arm/include/asm/mpu/layout.h b/xen/arch/arm/include/asm/mpu/layout.h new file mode 100644 index 0000000000..f9a5be2d6b --- /dev/null +++ b/xen/arch/arm/include/asm/mpu/layout.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#ifndef __ARM_MPU_LAYOUT_H__ +#define __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_MPU_LAYOUT_H__ */ +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */