From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range}
Date: Mon, 13 Sep 2021 01:53:27 -0400
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To: Andi Kleen <ak@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>, "Kuppuswamy, Sathyanarayanan" <sathyanarayanan.kuppuswamy@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Peter Zijlstra <peterz@infradead.org>, Andy Lutomirski <luto@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>, Richard Henderson <rth@twiddle.net>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, James E J Bottomley <James.Bottomley@hansenpartnership.com>, Helge Deller <deller@gmx.de>, "David S . Miller" <davem@davemloft.net>, Arnd Bergmann <arnd@arndb.de>, Jonathan Corbet <corbet@lwn.net>, Peter H Anvin <hpa@zytor.com>, Dave Hansen <dave.hansen@intel.com>, Tony Luck <tony.luck@intel.com>, Kirill Shutemov <kirill.shutemov@lin>

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
>