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Date:   Thu, 10 Feb 2022 02:21:29 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Borislav Petkov <bp@alien8.de>
Cc:     tglx@linutronix.de, mingo@redhat.com, dave.hansen@intel.com,
        luto@kernel.org, peterz@infradead.org,
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        tony.luck@intel.com, vkuznets@redhat.com, wanpengli@tencent.com,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2 23/29] x86/tdx: Add helper to convert memory between
 shared and private
Message-ID: <20220209232129.puktrgtvpovunexc@black.fi.intel.com>
References: <20220124150215.36893-1-kirill.shutemov@linux.intel.com>
 <20220124150215.36893-24-kirill.shutemov@linux.intel.com>
 <YgJePUqMEzHNqrsR@zn.tnic>
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Precedence: bulk

On Tue, Feb 08, 2022 at 01:12:45PM +0100, Borislav Petkov wrote:
> On Mon, Jan 24, 2022 at 06:02:09PM +0300, Kirill A. Shutemov wrote:
> > +	if (ret)
> > +		ret = -EIO;
> > +
> > +	if (ret || !enc)
> 
> Is the second case here after the "||" the conversion-to-shared where it
> only needs to notify with MapGPA and return?

Right. Memory accepting is required on the way to private.

I will rewrite and comment this code to make it more readable.

> > +		return ret;
> > +
> > +	/*
> > +	 * For shared->private conversion, accept the page using
> > +	 * TDX_ACCEPT_PAGE TDX module call.
> > +	 */
> > +	while (start < end) {
> > +		/* Try 2M page accept first if possible */
> > +		if (!(start & ~PMD_MASK) && end - start >= PMD_SIZE &&
> > +		    !tdx_accept_page(start, PG_LEVEL_2M)) {
> 
> What happens here if the module doesn't accept the page? No error
> reporting, no error handling, no warning, nada?

If it fails we fallback to 4k accept below.

We only report error if 4k accept fails.

-- 
 Kirill A. Shutemov