From: Penny Zheng <penny.zh...@arm.com> VMAP is widely used in ALTERNATIVE feature to remap a range of memory with new memory attributes. Since this is highly dependent on virtual address translation, we choose to fold VMAP in MMU system.
In this patch, we introduce a new Kconfig CONFIG_HAS_VMAP, and make it only support in MMU system on ARM architecture. And ALTERNATIVE now depend on VMAP. HARDEN_BRANCH_PREDICTOR is now gated on HAS_VMAP as speculative attacks are not possible on non MMU based systems (ie Cortex-R52, R82). See https://developer.arm.com/Arm%20Security%20Center/Speculative%20Processor%20Vulnerability. Split "https://patchwork.kernel.org/project/xen-devel/patch/20230626033443.2943270-16-penny.zh...@arm.com/"; into Arm specific Signed-off-by: Penny Zheng <penny.zh...@arm.com> Signed-off-by: Wei Chen <wei.c...@arm.com> Signed-off-by: Ayan Kumar Halder <ayan.kumar.hal...@amd.com> --- Changes from :- v1 - 1. HARDEN_BRANCH_PREDICTOR is now gated on HAS_VMAP. 2. cpuerrata.c is not gated on HAS_VMAP. xen/arch/arm/Kconfig | 7 ++++++- xen/arch/arm/setup.c | 2 ++ xen/include/xen/vmap.h | 2 ++ 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index 21d03d9f44..7d1dde89d7 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -12,7 +12,7 @@ config ARM_64 config ARM def_bool y select FUNCTION_ALIGNMENT_4B - select HAS_ALTERNATIVE + select HAS_ALTERNATIVE if HAS_VMAP select HAS_DEVICE_TREE select HAS_PASSTHROUGH select HAS_UBSAN @@ -58,9 +58,13 @@ config PADDR_BITS default 40 if ARM_PA_BITS_40 default 48 if ARM_64 +config HAS_VMAP + def_bool y + config MMU def_bool y select HAS_PMAP + select HAS_VMAP source "arch/Kconfig" @@ -171,6 +175,7 @@ config ARM_SSBD config HARDEN_BRANCH_PREDICTOR bool "Harden the branch predictor against aliasing attacks" if EXPERT + depends on HAS_VMAP default y help Speculation attacks against some high-performance processors rely on diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index cb2c0a16b8..7f686d2cca 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -447,7 +447,9 @@ void asmlinkage __init start_xen(unsigned long boot_phys_offset, * It needs to be called after do_initcalls to be able to use * stop_machine (tasklets initialized via an initcall). */ +#ifdef CONFIG_HAS_ALTERNATIVE apply_alternatives_all(); +#endif enable_errata_workarounds(); enable_cpu_features(); diff --git a/xen/include/xen/vmap.h b/xen/include/xen/vmap.h index fdae37e950..4c7dfe58ba 100644 --- a/xen/include/xen/vmap.h +++ b/xen/include/xen/vmap.h @@ -141,7 +141,9 @@ void *arch_vmap_virt_end(void); /* Initialises the VMAP_DEFAULT virtual range */ static inline void vm_init(void) { +#ifdef CONFIG_MMU vm_init_type(VMAP_DEFAULT, (void *)VMAP_VIRT_START, arch_vmap_virt_end()); +#endif } #endif /* __XEN_VMAP_H__ */ -- 2.25.1
