Re: [PATCH 1/2] Drivers: hv: vmbus: Remove x86-isms from arch independent drivers

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Nov 14, 2017 at 10:52:07AM -0700, kys@exchange.microsoft.com wrote:
> From: Michael Kelley <mikelley@microsoft.com>
> 
> hv_is_hypercall_page_setup() is used to check if Hyper-V is
> initialized, but a 'hypercall page' is an x86 implementation detail
> that isn't necessarily present on other architectures. Rename to the
> architecture independent hv_is_hyperv_initialized() and add check
> that x86_hyper is pointing to Hyper-V.  Use this function instead of
> direct references to x86-specific data structures in vmbus_drv.c,
> and remove now redundant call in hv_init(). Also remove 'x86' from
> the string name passed to cpuhp_setup_state().
> 
> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> ---
>  arch/x86/hyperv/hv_init.c       |   21 ++++++++++++++-------
>  arch/x86/include/asm/mshyperv.h |    4 ++--
>  drivers/hv/hv.c                 |    3 ---
>  drivers/hv/vmbus_drv.c          |    5 ++---
>  4 files changed, 18 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index aeb8edf..e5372c9 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -239,17 +239,24 @@ void hyperv_report_panic(struct pt_regs *regs, long err)
>  }
>  EXPORT_SYMBOL_GPL(hyperv_report_panic);
>  
> -bool hv_is_hypercall_page_setup(void)
> +bool hv_is_hyperv_initialized(void)
>  {
>  	union hv_x64_msr_hypercall_contents hypercall_msr;
>  
> -	/* Check if the hypercall page is setup */
> +	/*
> +	 * Ensure that we're really on Hyper-V, and not a KVM or Xen
> +	 * emulation of Hyper-V
> +	 */
> +	if (x86_hyper != &x86_hyper_ms_hyperv)
> +		return false;
> +
> +	/*
> +	 * Verify that earlier initialization succeeded by checking
> +	 * that the hypercall page is setup
> +	 */
>  	hypercall_msr.as_uint64 = 0;
>  	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
>  
> -	if (!hypercall_msr.enable)
> -		return false;
> -
> -	return true;
> +	return hypercall_msr.enable;
>  }
> -EXPORT_SYMBOL_GPL(hv_is_hypercall_page_setup);
> +EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index bd89104..740dc97 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -311,11 +311,11 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
>  void hyperv_setup_mmu_ops(void);
>  void hyper_alloc_mmu(void);
>  void hyperv_report_panic(struct pt_regs *regs, long err);
> -bool hv_is_hypercall_page_setup(void);
> +bool hv_is_hyperv_initialized(void);
>  void hyperv_cleanup(void);
>  #else /* CONFIG_HYPERV */
>  static inline void hyperv_init(void) {}
> -static inline bool hv_is_hypercall_page_setup(void) { return false; }
> +static inline bool hv_is_hyperv_initialized(void) { return false; }
>  static inline void hyperv_cleanup(void) {}
>  static inline void hyperv_setup_mmu_ops(void) {}
>  #endif /* CONFIG_HYPERV */
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 8267439..fe96aab 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -49,9 +49,6 @@ struct hv_context hv_context = {
>   */
>  int hv_init(void)
>  {
> -	if (!hv_is_hypercall_page_setup())
> -		return -ENOTSUPP;
> -
>  	hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
>  	if (!hv_context.cpu_context)
>  		return -ENOMEM;
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 4f3faf5..398643b 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -37,7 +37,6 @@
>  #include <linux/sched/task_stack.h>
>  
>  #include <asm/hyperv.h>
> -#include <asm/hypervisor.h>
>  #include <asm/mshyperv.h>
>  #include <linux/notifier.h>
>  #include <linux/ptrace.h>
> @@ -1053,7 +1052,7 @@ static int vmbus_bus_init(void)
>  	 * Initialize the per-cpu interrupt state and
>  	 * connect to the host.
>  	 */
> -	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv:online",
> +	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
>  				hv_synic_init, hv_synic_cleanup);
>  	if (ret < 0)
>  		goto err_alloc;
> @@ -1717,7 +1716,7 @@ static int __init hv_acpi_init(void)
>  {
>  	int ret, t;
>  
> -	if (x86_hyper != &x86_hyper_ms_hyperv)
> +	if (!hv_is_hyperv_initialized())
>  		return -ENODEV;
>  
>  	init_completion(&probe_event);
> -- 
> 1.7.1


Does not apply to 4.15-rc1 :(