RE: [PATCH char-misc 1/1] Hyper-V: Remove x86-isms from architecture independent Hyper-V drivers

[KY Srinivasan]

> -----Original Message-----
> From: mikelley@xxxxxxxxxxxxxxxxxxxxxx
> [mailto:mikelley@xxxxxxxxxxxxxxxxxxxxxx]
> Sent: Wednesday, October 25, 2017 3:31 PM
> To: gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx;
> vkuznets@xxxxxxxxxx; jasowang@xxxxxxxxxx;
> leann.ogasawara@xxxxxxxxxxxxx; marcelo.cerri@xxxxxxxxxxxxx; Stephen
> Hemminger <sthemmin@xxxxxxxxxxxxx>; KY Srinivasan
> <kys@xxxxxxxxxxxxx>
> Cc: Michael Kelley (EOSG) <Michael.H.Kelley@xxxxxxxxxxxxx>
> Subject: [PATCH char-misc 1/1] Hyper-V: Remove x86-isms from architecture
> independent Hyper-V drivers
> 
> [This sender failed our fraud detection checks and may not be who they
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> 
> From: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> 
> 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(). Use this function
> instead of direct references to x86-specific data structures in
> vmbus_drv.c, and remove 'x86' from the string name passed to
> cpuhp_setup_state().
> 
> Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> ---
>  arch/x86/hyperv/hv_init.c       | 4 ++--
>  arch/x86/include/asm/mshyperv.h | 4 ++--
>  drivers/hv/hv.c                 | 2 +-
>  drivers/hv/vmbus_drv.c          | 5 ++---
>  4 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index a5db63f728a2..38310bd091c2 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -236,7 +236,7 @@ void hyperv_report_panic(struct pt_regs *regs)
>  }
>  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;
> 
> @@ -249,4 +249,4 @@ bool hv_is_hypercall_page_setup(void)
> 
>         return true;
>  }
> -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 530f448fddaf..b001f898ccf3 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -311,11 +311,11 @@ void hyperv_init(void);
>  void hyperv_setup_mmu_ops(void);
>  void hyper_alloc_mmu(void);
>  void hyperv_report_panic(struct pt_regs *regs);
> -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 8267439dd1ee..ebad26053362 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -49,7 +49,7 @@ struct hv_context hv_context = {
>   */
>  int hv_init(void)
>  {
> -       if (!hv_is_hypercall_page_setup())
> +       if (!hv_is_hyperv_initialized())
>                 return -ENOTSUPP;
> 
>         hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 1da8e818f4de..12c51dc6bb7b 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>
> @@ -1047,7 +1046,7 @@ 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;
> @@ -1695,7 +1694,7 @@ static int __init hv_acpi_init(void)
>  {
>         int ret, t;
> 
> -       if (x86_hyper != &x86_hyper_ms_hyperv)
> +       if (!hv_is_hyperv_initialized())

We are checking to see if we are running on MSFT Hyper-V. This check was added to
deal with situations where Xen/KVM were emulating Hyper-V. It may not be safe to
replace this check with the call to hv_is_hyperv_initialized(). Perhaps we can add a new architecture
independent function to check the hypervisor - something like running_on_mshyperv() that can be used
here.

Regards,

K. Y
  
>                 return -ENODEV;
> 
>         init_completion(&probe_event);
> --
> 2.14.1