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Date:   Fri, 15 Oct 2021 16:19:52 -0700
From:   "Luck, Tony" <tony.luck@intel.com>
To:     Sean Christopherson <seanjc@google.com>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        naoya.horiguchi@nec.com, Andrew Morton <akpm@linux-foundation.org>,
        Jarkko Sakkinen <jarkko@kernel.org>,
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        Cathy Zhang <cathy.zhang@intel.com>, linux-sgx@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-mm@kvack.org,
        Reinette Chatre <reinette.chatre@intel.com>
Subject: Re: [PATCH v9 4/7] x86/sgx: Add SGX infrastructure to recover from
 poison
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References: <20211001164724.220532-1-tony.luck@intel.com>
 <20211011185924.374213-1-tony.luck@intel.com>
 <20211011185924.374213-5-tony.luck@intel.com>
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On Fri, Oct 15, 2021 at 11:10:32PM +0000, Sean Christopherson wrote:
> On Mon, Oct 11, 2021, Tony Luck wrote:
> > +	section = &sgx_epc_sections[page->section];
> > +	node = section->node;
> > +
> > +	spin_lock(&node->lock);
> > +
> > +	/* Already poisoned? Nothing more to do */
> > +	if (page->poison)
> > +		goto out;
> > +
> > +	page->poison = 1;
> > +
> > +	/*
> > +	 * If flags is zero, then the page is on a free list.
> > +	 * Move it to the poison page list.
> > +	 */
> > +	if (!page->flags) {
> 
> If the flag is inverted, this becomes
> 
> 	if (page->flags & SGX_EPC_PAGE_FREE) {

I like the inversion. I'll switch to SGX_EPC_PAGE_FREE

> 
> > +		list_del(&page->list);
> > +		list_add(&page->list, &sgx_poison_page_list);
> 
> list_move(), and needs the same protection for sgx_poison_page_list.

Didn't know list_move() existed. Will change all the lis_del+list_add
into list_move.

Also change the sgx_poison_page_list from global to per-node. Then
the adds will be safe (accessed while holding the node->lock).


Thanks for the review.

-Tony