linux-kernel - Re: [PATCH v11 04/10] iommu/vt-d: functions to copy data from old mem

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Message-ID: <1433772935.2952.47.camel@infradead.org>
Date:	Mon, 08 Jun 2015 15:15:35 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	"Li, Zhen-Hua" <zhen-hual@...com>
Cc:	indou.takao@...fujitsu.com, bhe@...hat.com, joro@...tes.org,
	vgoyal@...hat.com, dyoung@...hat.com,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
	alex.williamson@...hat.com, ddutile@...hat.com,
	ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
	doug.hatch@...com, jerry.hoemann@...com, tom.vaden@...com,
	li.zhang6@...com, lisa.mitchell@...com, billsumnerlinux@...il.com,
	rwright@...com
Subject: Re: [PATCH v11 04/10] iommu/vt-d: functions to copy data from old
 mem

On Mon, 2015-05-11 at 17:52 +0800, Li, Zhen-Hua wrote:
> Add some functions to copy the data from old kernel.
> These functions are used to copy context tables and page tables.
> 
> To avoid calling iounmap between spin_lock_irqsave and 
> spin_unlock_irqrestore,
> use a link here, store the pointers , and then use iounmap to free 
> them in
> another place.
> 
> Li, Zhen-hua:
>     The functions and logics.

Surely this isn't specific to the Intel IOMMU? Shouldn't it live
elsewhere — either in generic IOMMU code or perhaps in generic kexec
support code?

Don't we need to solve the same kexec problem on *all* platforms with
an IOMMU, and won't they all need something like this?

And I think you're misusing VTD_PAGE_{SHIFT,MASK} when you should be
using the normal PAGE_{SHIFT,MASK}. And shouldn't physical addresses be
phys_addr_t?

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation

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