RE: [PATCH v5 10/16] x86/hyperv: implement and use hv_smp_prepare_cpus

[Michael Kelley via Virtualization <virtualization@lists.linux-foundation.org>]

From: Wei Liu <wei.liu@kernel.org> Sent: Wednesday, January 20, 2021 4:01 AM
> 
> Microsoft Hypervisor requires the root partition to make a few
> hypercalls to setup application processors before they can be used.
> 
> Signed-off-by: Lillian Grassin-Drake <ligrassi@microsoft.com>
> Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
> Co-Developed-by: Lillian Grassin-Drake <ligrassi@microsoft.com>
> Co-Developed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
> Signed-off-by: Wei Liu <wei.liu@kernel.org>
> ---
> CPU hotplug and unplug is not yet supported in this setup, so those
> paths remain untouched.
> 
> v3: Always call native SMP preparation function.
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index c376d191a260..13d3b6dd21a3 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -31,6 +31,7 @@
>  #include <asm/reboot.h>
>  #include <asm/nmi.h>
>  #include <clocksource/hyperv_timer.h>
> +#include <asm/numa.h>
> 
>  /* Is Linux running as the root partition? */
>  bool hv_root_partition;
> @@ -212,6 +213,32 @@ static void __init hv_smp_prepare_boot_cpu(void)
>  	hv_init_spinlocks();
>  #endif
>  }
> +
> +static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +#ifdef CONFIG_X86_64
> +	int i;
> +	int ret;
> +#endif
> +
> +	native_smp_prepare_cpus(max_cpus);
> +
> +#ifdef CONFIG_X86_64
> +	for_each_present_cpu(i) {
> +		if (i == 0)
> +			continue;
> +		ret = hv_call_add_logical_proc(numa_cpu_node(i), i, cpu_physical_id(i));
> +		BUG_ON(ret);
> +	}
> +
> +	for_each_present_cpu(i) {
> +		if (i == 0)
> +			continue;
> +		ret = hv_call_create_vp(numa_cpu_node(i), hv_current_partition_id, i, i);
> +		BUG_ON(ret);
> +	}
> +#endif
> +}
>  #endif
> 
>  static void __init ms_hyperv_init_platform(void)
> @@ -368,6 +395,8 @@ static void __init ms_hyperv_init_platform(void)
> 
>  # ifdef CONFIG_SMP
>  	smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
> +	if (hv_root_partition)
> +		smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
>  # endif
> 
>  	/*
> --
> 2.20.1

Reviewed-by: Michael Kelley <mikelley@microsoft.com>

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