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Date:   Mon, 21 Nov 2022 15:40:19 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Michael Kelley <mikelley@microsoft.com>
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Subject: Re: [Patch v3 05/14] x86/mm: Handle decryption/re-encryption of
 bss_decrypted consistently
Message-ID: <Y3uN07qSlGqo0dNO@zn.tnic>
References: <1668624097-14884-1-git-send-email-mikelley@microsoft.com>
 <1668624097-14884-6-git-send-email-mikelley@microsoft.com>
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On Wed, Nov 16, 2022 at 10:41:28AM -0800, Michael Kelley wrote:
> Current code in sme_postprocess_startup() decrypts the bss_decrypted
> section when sme_me_mask is non-zero.  But code in
> mem_encrypt_free_decrytped_mem() re-encrypts the unused portion based
			^^

letters flipped.

> @@ -513,10 +513,14 @@ void __init mem_encrypt_free_decrypted_mem(void)
>  	npages = (vaddr_end - vaddr) >> PAGE_SHIFT;
>  
>  	/*
> -	 * The unused memory range was mapped decrypted, change the encryption
> -	 * attribute from decrypted to encrypted before freeing it.
> +	 * If the unused memory range was mapped decrypted, change the encryption
> +	 * attribute from decrypted to encrypted before freeing it. Base the
> +	 * re-encryption on the same condition used for the decryption in
> +	 * sme_postprocess_startup(). Higher level abstractions, such as
> +	 * CC_ATTR_MEM_ENCRYPT, aren't necessarily equivalent in a Hyper-V VM
> +	 * using vTOM, where sme_me_mask is always zero.

Good, an example why one needs to pay attention here.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette