[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 1/2] x86/cpu: maintain a parked CPU bitmap
Hi, On 20/11/2019 23:05, Chao Gao wrote: It helps to distinguish parked CPUs from those are really offlined or hot-added. We need to know the parked CPUs in order to do a special check against them to ensure that all CPUs, except those are really offlined or hot-added, have the same ucode version. Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx> --- Note that changes on ARM side are untested. --- xen/arch/arm/smpboot.c | 1 + xen/arch/x86/cpu/common.c | 4 ++++ xen/arch/x86/smpboot.c | 1 + xen/common/cpu.c | 4 ++++ xen/include/asm-arm/smp.h | 1 + xen/include/asm-x86/smp.h | 1 + xen/include/xen/cpumask.h | 1 + 7 files changed, 13 insertions(+) diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c index 00b64c3..1b57ba4 100644 --- a/xen/arch/arm/smpboot.c +++ b/xen/arch/arm/smpboot.c @@ -39,6 +39,7 @@ cpumask_t cpu_online_map; cpumask_t cpu_present_map; cpumask_t cpu_possible_map; +cpumask_var_t cpu_parked_map; You define cpu_parked_map but AFAIK it will never get allocated. The risk here is any access to that variable will result to a fault. Looking at the changes below, it looks like access in common code will be protected by park_offline_cpus. This is always false on Arm, so the compiler should remove any access to cpu_parked_map. With that in mind, I think it would be best to only provide a prototype for cpu_parked_map and so the linker can warn if someone used it. diff --git a/xen/include/asm-arm/smp.h b/xen/include/asm-arm/smp.h index fdbcefa..4b392fa 100644 --- a/xen/include/asm-arm/smp.h +++ b/xen/include/asm-arm/smp.h @@ -19,6 +19,7 @@ DECLARE_PER_CPU(cpumask_var_t, cpu_core_mask); * would otherwise prefer them to be off? */ #define park_offline_cpus false +extern cpumask_var_t cpu_parked_map; The prototype should be the same for all architectures. So is there any reason to duplicate it? Cheers, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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