linux-kernel - Re: [PATCH hyperv-next v4 09/16] Drivers: hv: Check message and event pages for non-NULL before iounmap()

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Message-ID: <CAMvTesCWTcXLxjOVyNF4pTqaQkXQsgKBXn1TQdK+n-9TfWfndA@mail.gmail.com>
Date: Fri, 25 Jul 2025 19:14:06 +0800
From: Tianyu Lan <ltykernel@...il.com>
To: Roman Kisel <romank@...ux.microsoft.com>
Cc: alok.a.tiwari@...cle.com, arnd@...db.de, bp@...en8.de, corbet@....net, 
	dave.hansen@...ux.intel.com, decui@...rosoft.com, haiyangz@...rosoft.com, 
	hpa@...or.com, kys@...rosoft.com, mhklinux@...look.com, mingo@...hat.com, 
	rdunlap@...radead.org, tglx@...utronix.de, Tianyu.Lan@...rosoft.com, 
	wei.liu@...nel.org, linux-arch@...r.kernel.org, linux-coco@...ts.linux.dev, 
	linux-doc@...r.kernel.org, linux-hyperv@...r.kernel.org, 
	linux-kernel@...r.kernel.org, x86@...nel.org, apais@...rosoft.com, 
	benhill@...rosoft.com, bperkins@...rosoft.com, sunilmut@...rosoft.com
Subject: Re: [PATCH hyperv-next v4 09/16] Drivers: hv: Check message and event
 pages for non-NULL before iounmap()

On Tue, Jul 15, 2025 at 6:16 AM Roman Kisel <romank@...ux.microsoft.com> wrote:
>
> It might happen that some hyp SynIC pages aren't allocated.
>
> Check for that and only then call iounmap().
>
> Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
> ---
>  drivers/hv/hv.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 820711e954d1..a8669843c56e 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -367,8 +367,10 @@ void hv_synic_disable_regs(unsigned int cpu)
>          */
>         simp.simp_enabled = 0;
>         if (ms_hyperv.paravisor_present || hv_root_partition()) {
> -               iounmap(hv_cpu->hyp_synic_message_page);
> -               hv_cpu->hyp_synic_message_page = NULL;
> +               if (hv_cpu->hyp_synic_message_page) {
> +                       iounmap(hv_cpu->hyp_synic_message_page);
> +                       hv_cpu->hyp_synic_message_page = NULL;
> +               }
>         } else {
>                 simp.base_simp_gpa = 0;
>         }
> @@ -379,8 +381,10 @@ void hv_synic_disable_regs(unsigned int cpu)
>         siefp.siefp_enabled = 0;
>
>         if (ms_hyperv.paravisor_present || hv_root_partition()) {
> -               iounmap(hv_cpu->hyp_synic_event_page);
> -               hv_cpu->hyp_synic_event_page = NULL;
> +               if (hv_cpu->hyp_synic_event_page) {
> +                       iounmap(hv_cpu->hyp_synic_event_page);
> +                       hv_cpu->hyp_synic_event_page = NULL;
> +               }
>         } else {
>                 siefp.base_siefp_gpa = 0;
>         }
> --
> 2.43.0
>
>

Reviewed-by: Tianyu Lan <tiala@...rosoft.com>
-- 
Thanks
Tianyu Lan