Re: [PATCH v3 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr_handler()

[Greg Kroah-Hartman]

On Wed, Sep 09, 2020 at 05:08:21PM +0800, shuo.a.liu@xxxxxxxxx wrote:
> From: Shuo Liu <shuo.a.liu@xxxxxxxxx>
> 
> The ACRN Hypervisor builds an I/O request when a trapped I/O access
> happens in User VM. Then, ACRN Hypervisor issues an upcall by sending
> a notification interrupt to the Service VM. HSM in the Service VM needs
> to hook the notification interrupt to handle I/O requests.
> 
> Notification interrupts from ACRN Hypervisor are already supported and
> a, currently uninitialized, callback called.
> 
> Export two APIs for HSM to setup/remove its callback.
> 
> Originally-by: Yakui Zhao <yakui.zhao@xxxxxxxxx>
> Signed-off-by: Shuo Liu <shuo.a.liu@xxxxxxxxx>
> Reviewed-by: Zhi Wang <zhi.a.wang@xxxxxxxxx>
> Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Fengwei Yin <fengwei.yin@xxxxxxxxx>
> Cc: Zhi Wang <zhi.a.wang@xxxxxxxxx>
> Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
> Cc: Yu Wang <yu1.wang@xxxxxxxxx>
> Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/acrn.h |  8 ++++++++
>  arch/x86/kernel/cpu/acrn.c  | 19 +++++++++++++++++++
>  2 files changed, 27 insertions(+)
>  create mode 100644 arch/x86/include/asm/acrn.h
> 
> diff --git a/arch/x86/include/asm/acrn.h b/arch/x86/include/asm/acrn.h
> new file mode 100644
> index 000000000000..ff259b69cde7
> --- /dev/null
> +++ b/arch/x86/include/asm/acrn.h
> @@ -0,0 +1,8 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_X86_ACRN_H
> +#define _ASM_X86_ACRN_H
> +
> +void acrn_setup_intr_handler(void (*handler)(void));
> +void acrn_remove_intr_handler(void);
> +
> +#endif /* _ASM_X86_ACRN_H */
> diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
> index 0b2c03943ac6..bd1d7e759a0f 100644
> --- a/arch/x86/kernel/cpu/acrn.c
> +++ b/arch/x86/kernel/cpu/acrn.c
> @@ -9,7 +9,11 @@
>   *
>   */
>  
> +#define pr_fmt(fmt) "acrn: " fmt
> +
>  #include <linux/interrupt.h>
> +
> +#include <asm/acrn.h>
>  #include <asm/apic.h>
>  #include <asm/cpufeatures.h>
>  #include <asm/desc.h>
> @@ -55,6 +59,21 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_acrn_hv_callback)
>  	set_irq_regs(old_regs);
>  }
>  
> +void acrn_setup_intr_handler(void (*handler)(void))
> +{
> +	if (acrn_intr_handler)
> +		pr_warn("Overwrite the acrn_intr_handler.\n");

What can someone do with this warning?  If it's really an "error", why
not prevent this from happening?

Don't scare users with things they can do nothing about.

thanks,

greg k-h