linux-kernel - Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support

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Date:   Mon, 02 May 2022 14:40:26 +1200
From:   Kai Huang <kai.huang@...el.com>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Cc:     "H . Peter Anvin" <hpa@...or.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Wander Lairson Costa <wander@...hat.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        marcelo.cerri@...onical.com, tim.gardner@...onical.com,
        khalid.elmously@...onical.com, philip.cox@...onical.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support


> +
> +	/* Get order for Quote buffer page allocation */
> +	order = get_order(quote_req.len);
> +
> +	/*
> +	 * Allocate buffer to get TD Quote from the VMM.
> +	 * Size needs to be 4KB aligned (which is already
> +	 * met in page allocation).
> +	 */
> +	tdquote = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
> +	if (!tdquote) {
> +		ret = -ENOMEM;
> +		goto quote_failed;
> +	}

You can use alloc_pages_exact().

> +
> +	/*
> +	 * Since this buffer will be shared with the VMM via GetQuote
> +	 * hypercall, decrypt it.
> +	 */
> +	ret = set_memory_decrypted((unsigned long)tdquote, 1UL << order);
> +	if (ret)
> +		goto quote_failed;


Again, Dave and Andi already commented you should use vmap() to avoid breaking
up the direct-mapping.  Please use vmap() instead.

https://lore.kernel.org/all/ce0feeec-a949-35f8-3010-b0d69acbbc2e@linux.intel.com/

Will review the rest later.


-- 
Thanks,
-Kai