Re: [PATCH v5 08/10] x86: hyperv: Add mshv_handler irq handler and setup function

Stanislav Kinsburskii
2025-02-26T23:43:13Z

On Wed, Feb 26, 2025 at 03:08:02PM -0800, Nuno Das Neves wrote:
> This will handle SYNIC interrupts such as intercepts, doorbells, and
> scheduling messages intended for the mshv driver.
>
> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> Reviewed-by: Wei Liu <wei.liu@kernel.org>
> Reviewed-by: Tianyu Lan <tiala@microsoft.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();

Can mshv_handler be defined as a weak symbol doing nothing instead
of defining it a null pointer?
This should allow to simplify this code and get rid of
hv_setup_mshv_handler, which looks redundant.

Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>

> +
> 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
>