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 Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/