linux-kernel - Re: [PATCH]intel-iommu batched iotlb flushes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 12 Feb 2008 07:54:48 -0800
From:	mark gross <mgross@...ux.intel.com>
To:	David Miller <davem@...emloft.net>
Cc:	muli@...ibm.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH]intel-iommu batched iotlb flushes

On Tue, Feb 12, 2008 at 01:00:06AM -0800, David Miller wrote:
> From: Muli Ben-Yehuda <muli@...ibm.com>
> Date: Tue, 12 Feb 2008 10:52:56 +0200
> 
> > The streaming DMA-API was designed to conserve IOMMU mappings for
> > machines where IOMMU mappings are a scarce resource, and is a poor
> > fit for a modern IOMMU such as VT-d with a 64-bit IO address space
> > (or even an IOMMU with a 32-bit address space such as Calgary) where
> > there are plenty of IOMMU mappings available.
> 
> For the 64-bit case what you are suggesting eventually amounts
> to mapping all available RAM in the IOMMU.

Something could be done:
we could enable drivers to have DMA-pools they manage that get mapped
and are re-used.

I would rather the DMA-pools be tied to PID's that way any bad behavior
would be limited to the address space of the process using the device.
I haven't thought about how hard this would be to do but it would be
nice.  I think this could be tricky.

Application sets up ring buffer of device DMA memory, passes this to
driver/stack.  Need to handle hitting high water marks and application
exit clean up sanely... 

--mgross

> 
> Although an extreme version of your suggestion, it would be the
> most efficient as it would require zero IOMMU flush operations.
> 
> But we'd lose things like protection and other benefits.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/