Messages in this thread | | | Date | Fri, 28 Sep 2012 16:25:55 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH 05/16] iommu/amd: Split device table initialization into irq and dma part |
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On Fri, Sep 28, 2012 at 10:17:53AM -0400, Konrad Rzeszutek Wilk wrote: > On Fri, Sep 28, 2012 at 02:23:55PM +0200, Joerg Roedel wrote: > > When the IOMMU is enabled very early (as with irq-remapping) > > some devices are still in BIOS hand. When dma is blocked > > early this can cause lots of IO_PAGE_FAULTs. So delay the > > DMA initialization and do it right before the dma_ops are > > initialized. > > To be secure, block all interrupts by default when irq-remapping is > > What are you trying to be secure against?
Against attacks of faked MSI msgs that could DoS the system. MSI messages are only specific DMA transactions in the end and a guest with a device assigned has control over its DMA engine and can thus send arbitrary interrupt requests to the host. There is a whole paper about such attacks. I can't find right now, but I send you a link when I find it.
Joerg
-- AMD Operating System Research Center
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