Re: [PATCH v6 05/11] xen/arm: define Xen start address for FVP BaseR platform

[Ayan Kumar Halder <ayankuma@xxxxxxx>]

Hi Wei,

On 04/11/2022 10:07, Wei Chen wrote:
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>
> 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 FVP BaseR platform's parameters. So we define default
> `XEN_START_ADDRESS` for FVP BaseR in its platform file.
>
> 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.
>
> And as we introduced Armv8-R platforms to Xen, that means the
> existed Arm64 platforms should not be listed in Armv8-R platform
> list, so we add !ARM_V8R dependency for these platforms.
>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> Signed-off-by: Jiamei.Xie <jiamei.xie@xxxxxxx>
> ---
>   xen/arch/arm/Kconfig                           | 11 +++++++++++
>   xen/arch/arm/include/asm/platforms/fvp_baser.h | 14 ++++++++++++++
>   xen/arch/arm/platforms/Kconfig                 | 16 +++++++++++++---
>   3 files changed, 38 insertions(+), 3 deletions(-)
>   create mode 100644 xen/arch/arm/include/asm/platforms/fvp_baser.h
>
> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> index ad592367bd..ac276307d6 100644
> --- a/xen/arch/arm/Kconfig
> +++ b/xen/arch/arm/Kconfig
> @@ -138,6 +138,17 @@ config TEE
>            This option enables generic TEE mediators support. It allows guests
>            to access real TEE via one of TEE mediators implemented in XEN.
>
> +config XEN_START_ADDRESS
> +       hex "Xen start address: keep default to use platform defined address"
> +       default 0xFFFFFFFF
> +       depends on HAS_MPU
> +       help
> +         This option allows to set the customized address at which Xen will be
> +         linked on MPU systems. 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.
> +
>   source "arch/arm/tee/Kconfig"
>
>   config STATIC_SHM
> diff --git a/xen/arch/arm/include/asm/platforms/fvp_baser.h 
> b/xen/arch/arm/include/asm/platforms/fvp_baser.h
> new file mode 100644
> index 0000000000..9450a411a9
> --- /dev/null
> +++ b/xen/arch/arm/include/asm/platforms/fvp_baser.h
> @@ -0,0 +1,14 @@
> +#ifndef __ASM_ARM_PLATFORMS_FVP_BASER_H__
> +#define __ASM_ARM_PLATFORMS_FVP_BASER_H__
> +
> +/*
> + * 0xFFFFFFFF indicates users haven't customized XEN_START_ADDRESS,
> + * we will use platform defined default address.
> + */
> +#if CONFIG_XEN_START_ADDRESS == 0xFFFFFFFF
> +#define XEN_START_ADDRESS 0x200000
> +#else
> +#define XEN_START_ADDRESS CONFIG_XEN_START_ADDRESS
> +#endif
> +
> +#endif /* __ASM_ARM_PLATFORMS_FVP_BASER_H__ */
> diff --git a/xen/arch/arm/platforms/Kconfig b/xen/arch/arm/platforms/Kconfig
> index c93a6b2756..0904793a0b 100644
> --- a/xen/arch/arm/platforms/Kconfig
> +++ b/xen/arch/arm/platforms/Kconfig
> @@ -1,6 +1,7 @@
>   choice
>          prompt "Platform Support"
>          default ALL_PLAT
> +       default FVP_BASER if ARM_V8R
I could not spot the patch which introduced ARM_V8R.

Can you rename this to ARM64_V8R ? The reason being the underlying code 
is specific to R82 ie 64 bit V8R.
- Ayan

>          ---help---
>          Choose which hardware platform to enable in Xen.
>
> @@ -8,13 +9,14 @@ choice
>
>   config ALL_PLAT
>          bool "All Platforms"
> +       depends on !ARM_V8R
>          ---help---
>          Enable support for all available hardware platforms. It doesn't
>          automatically select any of the related drivers.
>
>   config QEMU
>          bool "QEMU aarch virt machine support"
> -       depends on ARM_64
> +       depends on ARM_64 && !ARM_V8R
>          select GICV3
>          select HAS_PL011
>          ---help---
> @@ -23,7 +25,7 @@ config QEMU
>
>   config RCAR3
>          bool "Renesas RCar3 support"
> -       depends on ARM_64
> +       depends on ARM_64 && !ARM_V8R
>          select HAS_SCIF
>          select IPMMU_VMSA
>          ---help---
> @@ -31,14 +33,22 @@ config RCAR3
>
>   config MPSOC
>          bool "Xilinx Ultrascale+ MPSoC support"
> -       depends on ARM_64
> +       depends on ARM_64 && !ARM_V8R
>          select HAS_CADENCE_UART
>          select ARM_SMMU
>          ---help---
>          Enable all the required drivers for Xilinx Ultrascale+ MPSoC
>
> +config FVP_BASER
> +       bool "Fixed Virtual Platform BaseR support"
> +       depends on ARM_V8R
> +       help
> +         Enable platform specific configurations for Fixed Virtual
> +         Platform BaseR
> +
>   config NO_PLAT
>          bool "No Platforms"
> +       depends on !ARM_V8R
>          ---help---
>          Do not enable specific support for any platform.
>
> --
> 2.25.1