Thus far mem_access and mem_sharing memops had been able to signal
to Xen to start pulling responses off the corresponding rings. In this patch
we retire these memops and add them to the option to the vm_event_op domctl.
The vm_event_op domctl suboptions are the same for each ring thus we
consolidate them into XEN_VM_EVENT_ENABLE/DISABLE/RESUME.
As part of this patch in libxc we also rename the mem_access_enable/disable
functions to monitor_enable/disable and move them into xc_monitor.c.
Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>
In preparation for allowing for introspecting ARM and PV domains the old
control interface via the hvm_op hypercall is retired. A new control mechanism
is introduced via the domctl hypercall: monitor_op.
This patch aims to establish a base API on which future applications can build
on.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Tim Deegan <tim@xen.org>
In this patch we mechanically rename mem_event to vm_event. This patch
introduces no logic changes to the code. Using the name vm_event better
describes the intended use of this subsystem, which is not limited to memory
events. It can be used for off-loading the decision making logic into helper
applications when encountering various events during a VM's execution.
Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
The name of one of the mem_event rings still implies it is used only
for memory accesses, which is no longer the case. It is also used to
deliver various HVM events, thus the name "monitor" is more appropriate
in this setting.
Couple functions incorrectly labeled as part of mem_event is also renamed
to reflect that they belong to mem_access.
The mem_event subop definitions are also shortened to be more meaningful.
The tool side changes are only mechanical renaming to match these new names.
Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Vmx_disable_intercept_for_msr() will now refuse to disable interception of
MSRs needed for memory introspection. It is not possible to gate this on
mem_access being active for the domain, since by the time mem_access does
become active the interception for the interesting MSRs has already been
disabled (vmx_disable_intercept_for_msr() runs very early on).
Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Tim Deegan <tim@xen.org>
tools/libxc: Add helper function to setup ring for mem events
This patch adds a helper function that maps the ring, enables mem_event
and removes the ring from the guest physmap while the domain is paused.
This can be used by all mem_events but is only enabled for mem_access at
the moment.
tests/xen-access: Use helper API to setup ring and enable mem_access
Prior to this patch, xen-access was setting up the ring page in a way
that would give a malicous guest a window to write in to the shared ring
page. This patch fixes this by using the helper API that does it safely
on behalf of xen-access.
This is XSA-99.
Signed-off-by: Aravindh Puthiyaparambil <aravindp@cisco.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The emacs variable to set the C style from a local variable block is
c-file-style, not c-set-style.
Signed-off-by: David Vrabel <david.vrabel@citrix.com
This solves a long-standing issue in which the pages backing these rings were
pages belonging to dom0 user-space processes. Thus, if the process would die
unexpectedly, Xen would keep posting events to a page now belonging to some
other process.
We update all API-consumers in tree (xenpaging and xen-access).
This is an API/ABI change, so please speak up if it breaks your accumptions.
The patch touches tools, hypervisor x86/hvm bits, and hypervisor x86/mm bits.
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Tim Deegan <tim@xen.org>
Don't use the superfluous shared page, return the event channel directly as
part of the domctl struct, instead.
In-tree consumers (xenpaging, xen-access) updated. This is an ABI/API change,
so please voice any concerns.
Known pending issues:
- pager could die and its ring page could be used by some other process, yet
Xen retains the mapping to it.
- use a saner interface for the paging_load buffer.
This change also affects the x86/mm bits in the hypervisor that process the
mem_event setup domctl.
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Tim Deegan <tim@xen.org>
Per page operations in the paging, sharing, and access tracking subsystems are
all implemented with domctls (e.g. a domctl to evict one page, or to share one
page).
Under heavy load, the domctl path reveals a lack of scalability. The domctl
lock serializes dom0's vcpus in the hypervisor. When performing thousands of
per-page operations on dozens of domains, these vcpus will spin in the
hypervisor. Beyond the aggressive locking, an added inefficiency of blocking
vcpus in the domctl lock is that dom0 is prevented from re-scheduling any of
its other work-starved processes.
We retain the domctl interface for setting up and tearing down
paging/sharing/mem access for a domain. But we migrate all the per page
operations to use the memory_op hypercalls (e.g XENMEM_*).
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla>
Signed-off-by: Adin Scannell <adin@scannell.ca>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Tim Deegan <tim@xen.org>
Up to now a single ring buffer was used for mem_share, xenpaging and
xen-access. Each helper would have to cooperate and pull only its own
requests from the ring. Unfortunately this was not implemented. And
even if it was, it would make the whole concept fragile because a crash
or early exit of one helper would stall the others.
What happend up to now is that active xenpaging + memory_sharing would
push memsharing requests in the buffer. xenpaging is not prepared for
such requests.
This patch creates an independet ring buffer for mem_share, xenpaging
and xen-access and adds also new functions to enable xenpaging and
xen-access. The xc_mem_event_enable/xc_mem_event_disable functions will
be removed. The various XEN_DOMCTL_MEM_EVENT_* macros were cleaned up.
Due to the removal the API changed, so the SONAME will be changed too.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Tim Deegan <tim@xen.org>
* Creates HVMOPs for setting and getting memory access. The hypercalls
can set individual pages or the default access for new/refreshed
pages.
* Added functions to libxc to access these hypercalls.
Signed-off-by: Joe Epstein <jepstein98@gmail.com>
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
Acked-by: Tim Deegan <Tim.Deegan@citrix.com>
Tamas K Lengyel
Razvan Cojocaru
Aravindh Puthiyaparambil
David Vrabel
Tim Deegan
Andres Lagar-Cavilla
Olaf Hering
Joe Epstein