From: Jacob Pan <jacob.jun.pan@linux.intel.com>
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: Wed, 12 Jun 2019 12:02:09 -0700 [thread overview]
Message-ID: <20190612120209.29e90efe@jacob-builder> (raw)
In-Reply-To: <20190612175938.16428-1-jean-philippe.brucker@arm.com>
On Wed, 12 Jun 2019 18:59:38 +0100
Jean-Philippe Brucker <jean-philippe.brucker@arm.com> 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(+)
>
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index f45d8e9e59c3..fc00c5d4741b 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -105,15 +105,17 @@ struct iommu_fault_page_request {
> * @type: fault type from &enum iommu_fault_type
> * @padding: reserved for future use (should be zero)
> * @event: fault event, when @type is %IOMMU_FAULT_DMA_UNRECOV
> * @prm: Page Request message, when @type is %IOMMU_FAULT_PAGE_REQ
> + * @padding2: sets the fault size to allow for future extensions
> */
> struct iommu_fault {
> __u32 type;
> __u32 padding;
> union {
> struct iommu_fault_unrecoverable event;
> struct iommu_fault_page_request prm;
> + __u8 padding2[56];
> };
> };
>
Acked-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> /**
[Jacob Pan]
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-06-12 19:01 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-03 14:57 [PATCH v2 0/4] iommu: Add device fault reporting API Jean-Philippe Brucker
2019-06-03 14:57 ` [PATCH v2 1/4] driver core: Add per device iommu param Jean-Philippe Brucker
2019-06-03 14:57 ` [PATCH v2 2/4] iommu: Introduce device fault data Jean-Philippe Brucker
2019-06-03 22:08 ` Jacob Pan
2019-06-05 8:51 ` Tian, Kevin
2019-06-05 11:24 ` Jean-Philippe Brucker
2019-06-05 21:58 ` Jacob Pan
2019-06-05 17:37 ` Jacob Pan
2019-06-06 6:54 ` Tian, Kevin
2019-06-03 14:57 ` [PATCH v2 3/4] iommu: Introduce device fault report API Jean-Philippe Brucker
2019-06-03 14:57 ` [PATCH v2 4/4] iommu: Add recoverable fault reporting Jean-Philippe Brucker
2019-06-03 21:59 ` [PATCH v2 0/4] iommu: Add device fault reporting API Jacob Pan
2019-06-05 11:26 ` Jean-Philippe Brucker
2019-06-12 8:19 ` Joerg Roedel
2019-06-12 11:54 ` Jean-Philippe Brucker
2019-06-12 13:11 ` Joerg Roedel
2019-06-12 17:59 ` [PATCH] iommu: Add padding to struct iommu_fault Jean-Philippe Brucker
2019-06-12 19:02 ` Jacob Pan [this message]
2019-06-12 19:19 ` Auger Eric
2019-06-18 15:15 ` Joerg Roedel
2019-06-12 18:58 ` [PATCH v2 0/4] iommu: Add device fault reporting API Jacob Pan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190612120209.29e90efe@jacob-builder \
--to=jacob.jun.pan@linux.intel.com \
--cc=iommu@lists.linux-foundation.org \
--cc=jean-philippe.brucker@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).