linux-kernel - Re: [PATCH v4 4/5] lib/ioremap: Ensure phys_addr actually corresponds to a physical address

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Message-ID: <20181126190009.GG25719@linux.intel.com>
Date:   Mon, 26 Nov 2018 11:00:10 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Will Deacon <will.deacon@....com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        cpandya@...eaurora.org, toshi.kani@....com, tglx@...utronix.de,
        mhocko@...e.com, akpm@...ux-foundation.org
Subject: Re: [PATCH v4 4/5] lib/ioremap: Ensure phys_addr actually
 corresponds to a physical address

On Mon, Nov 26, 2018 at 05:07:46PM +0000, Will Deacon wrote:
> The current ioremap() code uses a phys_addr variable at each level of
> page table, which is confusingly offset by subtracting the base virtual
> address being mapped so that adding the current virtual address back on
> when iterating through the page table entries gives back the corresponding
> physical address.
> 
> This is fairly confusing and results in all users of phys_addr having to
> add the current virtual address back on. Instead, this patch just updates
> phys_addr when iterating over the page table entries, ensuring that it's
> always up-to-date and doesn't require explicit offsetting.
> 
> Cc: Chintan Pandya <cpandya@...eaurora.org>
> Cc: Toshi Kani <toshi.kani@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Will Deacon <will.deacon@....com>

Tested-by: Sean Christopherson <sean.j.christopherson@...el.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>