Commit ddc416cb authored Dec 13, 2013 by Mukesh Rathor Committed by Konrad Rzeszutek Wilk Jan 06, 2014

xen/pvh/x86: Define what an PVH guest is (v3).



Which is a PV guest with auto page translation enabled
and with vector callback. It is a cross between PVHVM and PV.

The Xen side defines PVH as (from docs/misc/pvh-readme.txt,
with modifications):

"* the guest uses auto translate:
 - p2m is managed by Xen
 - pagetables are owned by the guest
 - mmu_update hypercall not available
* it uses event callback and not vlapic emulation,
* IDT is native, so set_trap_table hcall is also N/A for a PVH guest.

For a full list of hcalls supported for PVH, see pvh_hypercall64_table
in arch/x86/hvm/hvm.c in xen.  From the ABI prespective, it's mostly a
PV guest with auto translate, although it does use hvm_op for setting
callback vector."

Also we use the PV cpuid, albeit we can use the HVM (native) cpuid.
However, we do have a fair bit of filtering in the xen_cpuid and
we can piggyback on that until the hypervisor/toolstack filters
the appropiate cpuids. Once that is done we can swap over to
use the native one.

We setup a Kconfig entry that is disabled by default and
cannot be enabled.

Note that on ARM the concept of PVH is non-existent. As Ian
put it: "an ARM guest is neither PV nor HVM nor PVHVM.
It's a bit like PVH but is different also (it's further towards
the H end of the spectrum than even PVH).". As such these
options (PVHVM, PVH) are never enabled nor seen on ARM
compilations.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

parent fc590efe

arch/x86/xen/Kconfig

+5 −0

Original line number	Diff line number	Diff line
		@@ -51,3 +51,8 @@ config XEN_DEBUG_FS
		Enable statistics output and various tuning options in debugfs.
		Enabling this option may incur a significant performance overhead.

		config XEN_PVH
		bool "Support for running as a PVH guest"
		depends on X86_64 && XEN && BROKEN
		select XEN_PVHVM
		def_bool n

include/xen/xen.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -29,4 +29,18 @@ extern enum xen_domain_type xen_domain_type;
		#define xen_initial_domain() (0)
		#endif /* CONFIG_XEN_DOM0 */

		#ifdef CONFIG_XEN_PVH
		/* This functionality exists only for x86. The XEN_PVHVM support exists
		* only in x86 world - hence on ARM it will be always disabled.
		* N.B. ARM guests are neither PV nor HVM nor PVHVM.
		* It's a bit like PVH but is different also (it's further towards the H
		* end of the spectrum than even PVH).
		*/
		#include <xen/features.h>
		#define xen_pvh_domain() (xen_pv_domain() && \
		xen_feature(XENFEAT_auto_translated_physmap) && \
		xen_have_vector_callback)
		#else
		#define xen_pvh_domain() (0)
		#endif
		#endif /* _XEN_XEN_H */

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