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Date:   Wed, 2 Nov 2022 13:05:36 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Pankaj Gupta <pankaj.gupta@amd.com>
Cc:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <dan.j.williams@intel.com>, <thomas.lendacky@amd.com>
Subject: Re: [PATCH] mm/memremap.c: map FS_DAX device memory as decrypted
Message-Id: <20221102130536.96c487d341544b7482eed038@linux-foundation.org>
In-Reply-To: <20221102160728.3184016-1-pankaj.gupta@amd.com>
References: <20221102160728.3184016-1-pankaj.gupta@amd.com>
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On Wed, 2 Nov 2022 11:07:28 -0500 Pankaj Gupta <pankaj.gupta@amd.com> wrote:

> virtio_pmem use devm_memremap_pages() to map the device memory.
> By default this memory is mapped as encrypted with SEV. Guest
> reboot changes the current encryption key and guest no longer
> properly decrypts the FSDAX device meta data.
> 
> Mark the corresponding device memory region for FSDAX devices
> (mapped with memremap_pages) as decrypted to retain the persistent
> memory property.
> 
> ...
>
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -335,6 +335,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
>  			WARN(1, "File system DAX not supported\n");
>  			return ERR_PTR(-EINVAL);
>  		}
> +		params.pgprot = pgprot_decrypted(params.pgprot);
>  		break;
>  	case MEMORY_DEVICE_GENERIC:
>  		break;

Should this be backported into earlier kernels?

Is b7b3c01b19159 a suitable Fixes: target?