linux-kernel - Re: [PATCHv2 02/12] x86/virt/tdx: Allocate page bitmap for Dynamic PAMT

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Message-ID: <c3f77974-f1d6-4a22-bd1d-2678427a9fb1@intel.com>
Date: Wed, 25 Jun 2025 11:06:16 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 pbonzini@...hat.com, seanjc@...gle.com, dave.hansen@...ux.intel.com
Cc: rick.p.edgecombe@...el.com, isaku.yamahata@...el.com,
 kai.huang@...el.com, yan.y.zhao@...el.com, chao.gao@...el.com,
 tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, kvm@...r.kernel.org,
 x86@...nel.org, linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 02/12] x86/virt/tdx: Allocate page bitmap for Dynamic
 PAMT

>  /*
>   * Locate a NUMA node which should hold the allocation of the @tdmr
>   * PAMT.  This node will have some memory covered by the TDMR.  The
> @@ -522,7 +534,16 @@ static int tdmr_set_up_pamt(struct tdmr_info *tdmr,
>  	 * and the total PAMT size.
>  	 */
>  	tdmr_pamt_size = 0;
> -	for (pgsz = TDX_PS_4K; pgsz < TDX_PS_NR; pgsz++) {
> +	pgsz = TDX_PS_4K;
> +
> +	/* With Dynamic PAMT, PAMT_4K is replaced with a bitmap */
> +	if (tdx_supports_dynamic_pamt(&tdx_sysinfo)) {
> +		pamt_size[pgsz] = tdmr_get_pamt_bitmap_sz(tdmr);
> +		tdmr_pamt_size += pamt_size[pgsz];
> +		pgsz++;
> +	}

This is the wrong place to do this.

Hide it in tdmr_get_pamt_sz(). Don't inject it in the main code flow
here and complicate the for loop.