linux-kernel - RE: [PATCH 1/3] iommu/vt-d: Use ida to manage domain id

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Message-ID: <BN9PR11MB527656492CD69CA4EA0EC7338C852@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Thu, 24 Apr 2025 07:37:16 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>, "Will
 Deacon" <will@...nel.org>, Robin Murphy <robin.murphy@....com>, "Jason
 Gunthorpe" <jgg@...pe.ca>
CC: "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/3] iommu/vt-d: Use ida to manage domain id

> From: Lu Baolu <baolu.lu@...ux.intel.com>
> Sent: Wednesday, April 23, 2025 11:10 AM
> 
>  static void free_dmar_iommu(struct intel_iommu *iommu)
>  {
> -	if (iommu->domain_ids) {
> -		bitmap_free(iommu->domain_ids);
> -		iommu->domain_ids = NULL;
> -	}
> +	ida_destroy(&iommu->domain_ida);

since ida_init() is in alloc_iommu() now, the destroy can be
moved to free_iommu().

> @@ -1399,14 +1356,13 @@ int domain_attach_iommu(struct dmar_domain
> *domain, struct intel_iommu *iommu)
>  		return 0;
>  	}
> 
> -	ndomains = cap_ndoms(iommu->cap);
> -	num = find_first_zero_bit(iommu->domain_ids, ndomains);
> -	if (num >= ndomains) {
> +	num = ida_alloc_range(&iommu->domain_ida, FLPT_DEFAULT_DID +
> 1,
> +			      cap_ndoms(iommu->cap) - 1, GFP_ATOMIC);

let's define a macro e.g. FIRST_DID for min.

Reviewed-by: Kevin Tian <kevin.tian@...el.com>