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Re: [Qemu-devel] [PATCH] ahci: map memory via device's address space ins

From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH] ahci: map memory via device's address space instead of address_space_memory
Date: Thu, 26 Feb 2015 23:02:24 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0

On 26/02/2015 22:31, Jordan Hargrave wrote:
> My OS initializes DMAR page tables and then enables the IOMMU translation. 
> Then OS initializes AHCI driver.  Writes VIRTUAL DMA to FIS registers.
> eg. FIS DMA address is 0x10000 (maps to some hardware physical address
> via iommu)
> The OS writes 0x00 PORT_FIS_ADDR_HI -> qemu calls map_page (0x00 << 32)
> | 0x7fae0000... 0x7fae0000 is stale, and is not in the IOMMU page map. 
> Causes a non-recoverable IOMMU fault.

That's a bug in QEMU.  map_page must be skipped unless PORT_CMD_FIS_ON
is set in pr->cmd (also, QEMU is never resetting PORT_CMD_FIS_ON when
PORT_CMD_FIS_RX goes down).


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