Re: [PATCH] iommu: Add padding to struct iommu_fault

From: Joerg Roedel <joro@8bytes.org>
To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Cc: iommu@lists.linux-foundation.org
Subject: Re: [PATCH] iommu: Add padding to struct iommu_fault
Date: Tue, 18 Jun 2019 17:15:55 +0200	[thread overview]
Message-ID: <20190618151555.GA21128@8bytes.org> (raw)
In-Reply-To: <20190612175938.16428-1-jean-philippe.brucker@arm.com>

On Wed, Jun 12, 2019 at 06:59:38PM +0100, Jean-Philippe Brucker wrote:
> Ease future extensions of struct iommu_fault_page_request and struct
> iommu_fault_unrecoverable by adding a few bytes of padding. That way, a
> new field can be added to either of these structures by simply introducing
> a new flag. To extend it after the size limit is reached, a new fault
> reporting structure will have to be negotiated with userspace.
> 
> With 56 bytes of padding, the total size of iommu_fault is 64 bytes and
> fits in a cache line on a lot of contemporary machines, while providing 16
> and 24 bytes of extension to structures iommu_fault_page_request and
> iommu_fault_unrecoverable respectively.
> 
> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
> ---
>  include/uapi/linux/iommu.h | 2 ++
>  1 file changed, 2 insertions(+)

Applied, thanks.
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