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From: David Vrabel <david.vrabel@citrix.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xensource.com, Tim Deegan <tim@xen.org>,
	Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH RFC 0/3] introduce XENMEM_get_dma_buf and XENMEM_put_dma_buf
Date: Thu, 1 Aug 2013 10:41:06 +0100	[thread overview]
Message-ID: <51FA2D32.4050001@citrix.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1307311850010.4893@kaball.uk.xensource.com>

On 31/07/13 18:57, Stefano Stabellini wrote:
> Hi all,
> this patch series introduces two new hypercalls to allow autotranslate
> guests to allocate a contiguous buffer in machine addresses.
> The XENMEM_get_dma_buf returns the mfns and makes sure to pin the pages
> so that the hypervisor won't change their p2m mappings while in use.
> XENMEM_put_dma_buf simply unpins the pages.

Can you expand on what circumstances the hypervisor would otherwise
adjust the p2m?  How has x86 avoided these problems?

> The implementation of XENMEM_put_dma_buf is missing, as it's actually
> unused.
> 
> The page pinning is also missing from this series. I would appreciate
> feedback on the best way to implement it, especially on x86.

David

  parent reply	other threads:[~2013-08-01  9:41 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-31 17:57 [PATCH RFC 0/3] introduce XENMEM_get_dma_buf and XENMEM_put_dma_buf Stefano Stabellini
2013-07-31 17:57 ` [PATCH RFC 1/3] xen/arm: implement steal_page Stefano Stabellini
2013-07-31 17:57 ` [PATCH RFC 2/3] xen: provide empty stubs for guest_physmap_(un)pin_range on arm and x86 Stefano Stabellini
2013-07-31 17:57 ` [PATCH RFC 3/3] xen: introduce XENMEM_get_dma_buf and XENMEM_put_dma_buf Stefano Stabellini
2013-08-01  9:41 ` David Vrabel [this message]
2013-08-01 14:55   ` [PATCH RFC 0/3] " Ian Campbell

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