linux-kernel - Re: [PATCH v10 10/16] x86/virt/tdx: Allocate and set up PAMTs for TDMRs

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Message-ID: <ce375c4a84bb0aafae73df8ddbcd1dc7024cee79.camel@intel.com>
Date:   Tue, 21 Mar 2023 08:05:52 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Dong, Eddie" <eddie.dong@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "Hansen, Dave" <dave.hansen@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "imammedo@...hat.com" <imammedo@...hat.com>,
        "Gao, Chao" <chao.gao@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v10 10/16] x86/virt/tdx: Allocate and set up PAMTs for
 TDMRs

On Tue, 2023-03-21 at 07:44 +0000, Dong, Eddie wrote:
> > 
> > +/*
> > + * Calculate PAMT size given a TDMR and a page size.  The returned
> > + * PAMT size is always aligned up to 4K page boundary.
> > + */
> > +static unsigned long tdmr_get_pamt_sz(struct tdmr_info *tdmr, int pgsz,
> > +				      u16 pamt_entry_size)
> > +{
> > +	unsigned long pamt_sz, nr_pamt_entries;
> > +
> > +	switch (pgsz) {
> > +	case TDX_PS_4K:
> > +		nr_pamt_entries = tdmr->size >> PAGE_SHIFT;
> > +		break;
> > +	case TDX_PS_2M:
> > +		nr_pamt_entries = tdmr->size >> PMD_SHIFT;
> > +		break;
> > +	case TDX_PS_1G:
> > +		nr_pamt_entries = tdmr->size >> PUD_SHIFT;
> > +		break;
> > +	default:
> > +		WARN_ON_ONCE(1);
> > +		return 0;
> > +	}
> > +
> > +	pamt_sz = nr_pamt_entries * pamt_entry_size;
> > +	/* TDX requires PAMT size must be 4K aligned */
> > +	pamt_sz = ALIGN(pamt_sz, PAGE_SIZE);
> 
> Should we ALIGN_UP for safe ?

Hi Eddie,

ALIGN() already does align up.

> 
> > +
> > +	return pamt_sz;
> > +}
> > +