linux-kernel - Re: [PATCH v11 12/20] x86/virt/tdx: Allocate and set up PAMTs for TDMRs

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Message-ID: <b516b042-bec8-63fa-2474-72301fec67c7@suse.com>
Date:   Thu, 15 Jun 2023 10:48:17 +0300
From:   Nikolay Borisov <nik.borisov@...e.com>
To:     Kai Huang <kai.huang@...el.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     linux-mm@...ck.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, tony.luck@...el.com,
        peterz@...radead.org, tglx@...utronix.de, seanjc@...gle.com,
        pbonzini@...hat.com, david@...hat.com, dan.j.williams@...el.com,
        rafael.j.wysocki@...el.com, ying.huang@...el.com,
        reinette.chatre@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, bagasdotme@...il.com,
        sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v11 12/20] x86/virt/tdx: Allocate and set up PAMTs for
 TDMRs



On 4.06.23 г. 17:27 ч., Kai Huang wrote:

<snip>

>   /*
>    * Construct a list of TDMRs on the preallocated space in @tdmr_list
>    * to cover all TDX memory regions in @tmb_list based on the TDX module
> @@ -487,10 +684,13 @@ static int construct_tdmrs(struct list_head *tmb_list,
>   	if (ret)
>   		return ret;
>   
> +	ret = tdmrs_set_up_pamt_all(tdmr_list, tmb_list,
> +			sysinfo->pamt_entry_size);
> +	if (ret)
> +		return ret;
>   	/*
>   	 * TODO:
>   	 *
> -	 *  - Allocate and set up PAMTs for each TDMR.
>   	 *  - Designate reserved areas for each TDMR.
>   	 *
>   	 * Return -EINVAL until constructing TDMRs is done
> @@ -547,6 +747,11 @@ static int init_tdx_module(void)
>   	 *  Return error before all steps are done.
>   	 */
>   	ret = -EINVAL;
> +	if (ret)
> +		tdmrs_free_pamt_all(&tdx_tdmr_list);
> +	else
> +		pr_info("%lu KBs allocated for PAMT.\n",
> +				tdmrs_count_pamt_pages(&tdx_tdmr_list) * 4);

Why not put the pr_info right after the 'if (ret)' check following 
tdmrs_setup_pamt_all(). And make the tdmrs_free_pamt_all call 
unconditional.

It seems the main reason for having a bunch of conditionals in the exit 
reason is that you share the put_online_mems(); in both the success and 
failure cases. If you simply add :


put_online_mems();
return 0;

// failure labels follow

Then you can make do without the if (ret) checks and have straight line 
code doing the error handling.

>   out_free_tdmrs:
>   	if (ret)
>   		free_tdmr_list(&tdx_tdmr_list);
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index c20848e76469..e8110e1a9980 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -133,6 +133,7 @@ struct tdx_memblock {
>   	struct list_head list;
>   	unsigned long start_pfn;
>   	unsigned long end_pfn;
> +	int nid;
>   };
>   
>   struct tdmr_info_list {