b097186fd2
This patchset: PV guests under Xen are running in an non-contiguous memory architecture. When PCI pass-through is utilized, this necessitates an IOMMU for translating bus (DMA) to virtual and vice-versa and also providing a mechanism to have contiguous pages for device drivers operations (say DMA operations). Specifically, under Xen the Linux idea of pages is an illusion. It assumes that pages start at zero and go up to the available memory. To help with that, the Linux Xen MMU provides a lookup mechanism to translate the page frame numbers (PFN) to machine frame numbers (MFN) and vice-versa. The MFN are the "real" frame numbers. Furthermore memory is not contiguous. Xen hypervisor stitches memory for guests from different pools, which means there is no guarantee that PFN==MFN and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are allocated in descending order (high to low), meaning the guest might never get any MFN's under the 4GB mark. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Albert Herranz <albert_herranz@yahoo.es> Cc: Ian Campbell <Ian.Campbell@citrix.com>
70 lines
2.1 KiB
Plaintext
70 lines
2.1 KiB
Plaintext
menu "Xen driver support"
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depends on XEN
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config XEN_BALLOON
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bool "Xen memory balloon driver"
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default y
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help
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The balloon driver allows the Xen domain to request more memory from
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the system to expand the domain's memory allocation, or alternatively
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return unneeded memory to the system.
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config XEN_SCRUB_PAGES
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bool "Scrub pages before returning them to system"
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depends on XEN_BALLOON
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default y
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help
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Scrub pages before returning them to the system for reuse by
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other domains. This makes sure that any confidential data
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is not accidentally visible to other domains. Is it more
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secure, but slightly less efficient.
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If in doubt, say yes.
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config XEN_DEV_EVTCHN
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tristate "Xen /dev/xen/evtchn device"
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default y
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help
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The evtchn driver allows a userspace process to triger event
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channels and to receive notification of an event channel
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firing.
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If in doubt, say yes.
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config XENFS
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tristate "Xen filesystem"
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default y
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help
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The xen filesystem provides a way for domains to share
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information with each other and with the hypervisor.
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For example, by reading and writing the "xenbus" file, guests
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may pass arbitrary information to the initial domain.
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If in doubt, say yes.
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config XEN_COMPAT_XENFS
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bool "Create compatibility mount point /proc/xen"
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depends on XENFS
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default y
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help
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The old xenstore userspace tools expect to find "xenbus"
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under /proc/xen, but "xenbus" is now found at the root of the
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xenfs filesystem. Selecting this causes the kernel to create
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the compatibility mount point /proc/xen if it is running on
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a xen platform.
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If in doubt, say yes.
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config XEN_SYS_HYPERVISOR
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bool "Create xen entries under /sys/hypervisor"
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depends on SYSFS
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select SYS_HYPERVISOR
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default y
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help
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Create entries under /sys/hypervisor describing the Xen
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hypervisor environment. When running native or in another
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virtual environment, /sys/hypervisor will still be present,
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but will have no xen contents.
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config SWIOTLB_XEN
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def_bool y
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depends on SWIOTLB
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endmenu
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