linux-kernel - RE: [PATCH v5 08/10] x86: hyperv: Add mshv_handler irq handler and setup function

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Message-ID:
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Date: Fri, 7 Mar 2025 17:44:50 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
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Subject: RE: [PATCH v5 08/10] x86: hyperv: Add mshv_handler irq handler and
 setup function

From: Nuno Das Neves <nunodasneves@...ux.microsoft.com> Sent: Wednesday, February 26, 2025 3:08 PM

> 
> This will handle SYNIC interrupts such as intercepts, doorbells, and
> scheduling messages intended for the mshv driver.

Could you provide a bit more detailed commit message? How does
the mshv_handler() relate to the vmbus_handler()? From the code
mshv_handler() goes first, and I'm assuming it processes what it
knows about (intercepts, doorbells, scheduling messages?) and
then hands off control to the vmbus_handler() to handle the usual
VMbus-related message and channel interrupts. But it would be
nice to have the commit message or code comments describe the
overall intent and any obscure aspects of the relationship.

And avoid references to "This" or "This patch". :-)

> 
> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
> Reviewed-by: Wei Liu <wei.liu@...nel.org>
> Reviewed-by: Tianyu Lan <tiala@...rosoft.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 9 +++++++++
>  drivers/hv/hv_common.c         | 5 +++++
>  include/asm-generic/mshyperv.h | 1 +
>  3 files changed, 15 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 0116d0e96ef9..616e9a5d77b4 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -107,6 +107,7 @@ void hv_set_msr(unsigned int reg, u64 value)
>  }
>  EXPORT_SYMBOL_GPL(hv_set_msr);
> 
> +static void (*mshv_handler)(void);
>  static void (*vmbus_handler)(void);
>  static void (*hv_stimer0_handler)(void);
>  static void (*hv_kexec_handler)(void);
> @@ -117,6 +118,9 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
>  	struct pt_regs *old_regs = set_irq_regs(regs);
> 
>  	inc_irq_stat(irq_hv_callback_count);
> +	if (mshv_handler)
> +		mshv_handler();
> +
>  	if (vmbus_handler)
>  		vmbus_handler();
> 
> @@ -126,6 +130,11 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
>  	set_irq_regs(old_regs);
>  }
> 
> +void hv_setup_mshv_handler(void (*handler)(void))
> +{
> +	mshv_handler = handler;
> +}
> +
>  void hv_setup_vmbus_handler(void (*handler)(void))
>  {
>  	vmbus_handler = handler;
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index 2763cb6d3678..f5a07fd9a03b 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -677,6 +677,11 @@ void __weak hv_remove_vmbus_handler(void)
>  }
>  EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
> 
> +void __weak hv_setup_mshv_handler(void (*handler)(void))
> +{
> +}
> +EXPORT_SYMBOL_GPL(hv_setup_mshv_handler);
> +
>  void __weak hv_setup_kexec_handler(void (*handler)(void))
>  {
>  }
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index 1f46d19a16aa..a05f12e63ccd 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -208,6 +208,7 @@ void hv_setup_kexec_handler(void (*handler)(void));
>  void hv_remove_kexec_handler(void);
>  void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs));
>  void hv_remove_crash_handler(void);
> +void hv_setup_mshv_handler(void (*handler)(void));
> 
>  extern int vmbus_interrupt;
>  extern int vmbus_irq;
> --
> 2.34.1