linux-kernel - Re: [PATCH v4 6/6] iommu/amd: Lock DTE before updating the entry with WRITE

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Message-ID: <20240926195813.GB229871@nvidia.com>
Date: Thu, 26 Sep 2024 16:58:13 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc: linux-kernel@...r.kernel.org, iommu@...ts.linux.dev, joro@...tes.org,
	robin.murphy@....com, vasant.hegde@....com, kevin.tian@...el.com,
	jon.grimm@....com, santosh.shukla@....com, pandoh@...gle.com,
	kumaranand@...gle.com
Subject: Re: [PATCH v4 6/6] iommu/amd: Lock DTE before updating the entry
 with WRITE_ONCE()

On Mon, Sep 16, 2024 at 05:18:05PM +0000, Suravee Suthikulpanit wrote:
> When updating only within a 64-bit tuple of a DTE, just lock the DTE and
> use WRITE_ONCE() because it is writing to memory read back by HW.
> 
> Suggested-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  drivers/iommu/amd/iommu.c | 42 ++++++++++++++++++++++-----------------
>  1 file changed, 24 insertions(+), 18 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason