Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range}

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: "Kuppuswamy,
	Sathyanarayanan" <sathyanarayanan.kuppuswamy@linux.intel.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
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	Kirill Shutemov <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range}
Date: Mon, 13 Sep 2021 01:53:27 -0400	[thread overview]
Message-ID: <20210913013815-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20210911195006-mutt-send-email-mst@kernel.org>

On Sat, Sep 11, 2021 at 07:54:43PM -0400, Michael S. Tsirkin wrote:
> On Fri, Sep 10, 2021 at 09:34:45AM -0700, Andi Kleen wrote:
> > > > that's why
> > > > an extra level of defense of ioremap opt-in is useful.
> > > OK even assuming this, why is pci_iomap opt-in useful?
> > > That never happens before probe - there's simply no pci_device then.
> > 
> > 
> > Hmm, yes that's true. I guess we can make it default to opt-in for
> > pci_iomap.
> > 
> > It only really matters for device less ioremaps.
> 
> OK. And same thing for other things with device, such as
> devm_platform_ioremap_resource.
> If we agree on all that, this will basically remove virtio
> changes from the picture ;)

Something else that was pointed out to me:

         fs->window_kaddr = devm_memremap_pages(&vdev->dev, pgmap);
         if (IS_ERR(fs->window_kaddr))
                 return PTR_ERR(fs->window_kaddr);

looks like if we forget to set the shared flag then it will
corrupt the DAX data?

> -- 
> MST
> 

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