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

From: Kai Huang <kai.huang@intel.com>
To: Kuppuswamy Sathyanarayanan 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org
Cc: "H . Peter Anvin" <hpa@zytor.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
	Wander Lairson Costa <wander@redhat.com>,
	Isaku Yamahata <isaku.yamahata@gmail.com>,
	marcelo.cerri@canonical.com, tim.gardner@canonical.com,
	khalid.elmously@canonical.com, philip.cox@canonical.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support
Date: Mon, 02 May 2022 14:40:26 +1200	[thread overview]
Message-ID: <243e918c523320ba3d216cbe22d24fe5ce33f370.camel@intel.com> (raw)
In-Reply-To: <20220501183500.2242828-4-sathyanarayanan.kuppuswamy@linux.intel.com>

> +
> +	/* 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