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[Xen-devel] [VTD] [PATCH] Ignore USB RMRR for HVM guest


  • To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Han, Weidong" <weidong.han@xxxxxxxxx>
  • Date: Wed, 19 Mar 2008 10:46:28 +0800
  • Cc: "Kay, Allen M" <allen.m.kay@xxxxxxxxx>
  • Delivery-date: Tue, 18 Mar 2008 19:55:59 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AciJa23CI5sdTtz3SJeDbdL+c4ooRA==
  • Thread-topic: [Xen-devel] [VTD] [PATCH] Ignore USB RMRR for HVM guest

USB controller RMRR (0xed000 - 0xeffff) conflicts with HVM guest bios
region. Setting identity mapping for it will cover the guest bios region
in p2m table. This causes system crash. 

As VT-d spec says, USB controller RMRR is used in case of DMA performed
by a USB controller under BIOS SMM control for legacy keyboard
emulation. Whereas, current guest BIOS doesn't support emulating
stardand
Keyboard/mouse, and it also doesn't support SMM mode. Actually it is no
chance to use USB controller RMRR now.

This patch ignores the USB controller RMRR for HVM guest.

Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>

Attachment: usb-rmrr.patch
Description: usb-rmrr.patch

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