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From: Pavel Fedin <p.fedin@samsung.com>
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Date: Mon, 07 Dec 2015 13:53:41 +0300
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Subject: Re: [Qemu-devel] [PATCH] vfio: Align iova also to IOMMU page size
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To: 'Alex Williamson' <alex.williamson@redhat.com>, 'Peter Maydell' <peter.maydell@linaro.org>
Cc: 'QEMU Developers' <qemu-devel@nongnu.org>

 Hello!

> TAGET_PAGE_ALIGN tells us that it *could* be a valid DMA target =
though.
> The VM model is capable of using that as a page size, which means we
> assume it is and want to generate a fault.

 We seem to have looped back. So...
 It is possible to fix this according to this assumption. In this case =
we would need to make TARGET_PAGE_BITS a variable. If we are emulating =
ancient armv5te, it will be set to 10. For modern targets, ARMv6 and =
newer, it will be 12.
 Peter, would you ACK this approach? BTW, we even have a kind of hack in =
target-arm/cpu.h:
--- cut ---
#if defined(CONFIG_USER_ONLY)
#define TARGET_PAGE_BITS 12
#else
/* The ARM MMU allows 1k pages.  */
/* ??? Linux doesn't actually use these, and they're deprecated in =
recent
   architecture revisions.  Maybe a configure option to disable them.  =
*/
#define TARGET_PAGE_BITS 10
#endif
--- cut ---

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia