linux-kernel - Re: [PATCH v7 5/7] Drivers: hv: Improve region overlap detection in partition create

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Message-ID: <aS2vB4QS_VeHrRvB@anirudh-surface.localdomain>
Date: Mon, 1 Dec 2025 15:06:47 +0000
From: Anirudh Rayabharam <anirudh@...rudhrb.com>
To: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
	decui@...rosoft.com, linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 5/7] Drivers: hv: Improve region overlap detection in
 partition create

On Wed, Nov 26, 2025 at 02:09:17AM +0000, Stanislav Kinsburskii wrote:
> Refactor region overlap check in mshv_partition_create_region to use
> mshv_partition_region_by_gfn for both start and end guest PFNs, replacing
> manual iteration.
> 
> This is a cleaner approach that leverages existing functionality to
> accurately detect overlapping memory regions.
> 
> Signed-off-by: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
> ---
>  drivers/hv/mshv_root_main.c |    8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index 5dfb933da981..ae600b927f49 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -1086,13 +1086,9 @@ static int mshv_partition_create_region(struct mshv_partition *partition,
>  	u64 nr_pages = HVPFN_DOWN(mem->size);
>  
>  	/* Reject overlapping regions */
> -	hlist_for_each_entry(rg, &partition->pt_mem_regions, hnode) {
> -		if (mem->guest_pfn + nr_pages <= rg->start_gfn ||
> -		    rg->start_gfn + rg->nr_pages <= mem->guest_pfn)
> -			continue;
> -
> +	if (mshv_partition_region_by_gfn(partition, mem->guest_pfn) ||
> +	    mshv_partition_region_by_gfn(partition, mem->guest_pfn + nr_pages - 1))
>  		return -EEXIST;
> -	}
>  
>  	rg = mshv_region_create(mem->guest_pfn, nr_pages,
>  				mem->userspace_addr, mem->flags,
> 
> 

Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@...rudhrb.com>