linux-kernel - Re: [PATCH 2/7] vfio: Export unmap_mapping

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Message-ID: <YRLLx5O6gleDqsMR@t490s>
Date:   Tue, 10 Aug 2021 14:56:07 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Alex Williamson <alex.williamson@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org, jgg@...dia.com
Subject: Re: [PATCH 2/7] vfio: Export unmap_mapping_range() wrapper

On Thu, Aug 05, 2021 at 11:07:22AM -0600, Alex Williamson wrote:
> +void vfio_device_unmap_mapping_range(struct vfio_device *device,
> +				     loff_t start, loff_t len)
> +{
> +	unmap_mapping_range(device->inode->i_mapping, start, len, true);

(not a big deal, but still raise this up)

It seems to me VFIO MMIO regions do not allow private maps, so even_cow==true
should be the same with even_cow==false. even_cow==true will just check the
page mapping for each pte even though they should just all match, imho, so
logically "false" should work the same and should be tiny-little faster.

Thanks,

> +}
> +EXPORT_SYMBOL_GPL(vfio_device_unmap_mapping_range);

-- 
Peter Xu