linux_dsm_epyc7002/arch/x86/xen/Kconfig
Juergen Gross c70727a5bc xen: allow more than 512 GB of RAM for 64 bit pv-domains
64 bit pv-domains under Xen are limited to 512 GB of RAM today. The
main reason has been the 3 level p2m tree, which was replaced by the
virtual mapped linear p2m list. Parallel to the p2m list which is
being used by the kernel itself there is a 3 level mfn tree for usage
by the Xen tools and eventually for crash dump analysis. For this tree
the linear p2m list can serve as a replacement, too. As the kernel
can't know whether the tools are capable of dealing with the p2m list
instead of the mfn tree, the limit of 512 GB can't be dropped in all
cases.

This patch replaces the hard limit by a kernel parameter which tells
the kernel to obey the 512 GB limit or not. The default is selected by
a configuration parameter which specifies whether the 512 GB limit
should be active per default for domUs (domain save/restore/migration
and crash dump analysis are affected).

Memory above the domain limit is returned to the hypervisor instead of
being identity mapped, which was wrong anyway.

The kernel configuration parameter to specify the maximum size of a
domain can be deleted, as it is not relevant any more.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
2015-08-20 12:24:24 +01:00

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#
# This Kconfig describes xen options
#
config XEN
bool "Xen guest support"
depends on PARAVIRT
select PARAVIRT_CLOCK
select XEN_HAVE_PVMMU
depends on X86_64 || (X86_32 && X86_PAE)
depends on X86_TSC
help
This is the Linux Xen port. Enabling this will allow the
kernel to boot in a paravirtualized environment under the
Xen hypervisor.
config XEN_DOM0
def_bool y
depends on XEN && PCI_XEN && SWIOTLB_XEN
depends on X86_LOCAL_APIC && X86_IO_APIC && ACPI && PCI
config XEN_PVHVM
def_bool y
depends on XEN && PCI && X86_LOCAL_APIC
config XEN_512GB
bool "Limit Xen pv-domain memory to 512GB"
depends on XEN && X86_64
default y
help
Limit paravirtualized user domains to 512GB of RAM.
The Xen tools and crash dump analysis tools might not support
pv-domains with more than 512 GB of RAM. This option controls the
default setting of the kernel to use only up to 512 GB or more.
It is always possible to change the default via specifying the
boot parameter "xen_512gb_limit".
config XEN_SAVE_RESTORE
bool
depends on XEN
select HIBERNATE_CALLBACKS
default y
config XEN_DEBUG_FS
bool "Enable Xen debug and tuning parameters in debugfs"
depends on XEN && DEBUG_FS
default n
help
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 && XEN_PVHVM
def_bool n