xen/arm: Data abort exception (R/W) mem_events.

This patch enables to store, set, check and deliver LPAE R/W mem_events.
As the LPAE PTE's lack enough available software programmable bits,
we store the permissions in a Radix tree, where the key is the pfn
of a 4k page. Only settings other than p2m_access_rwx are saved
in the Radix tree.

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
---
v5: - Move p2m_set_entry's logic into apply_one_level via
      a new p2m_op, MEMACCESS.
v4: - Add p2m_mem_access_radix_set function to be called
      when inserting new PTE's and when updating existing entries.
    - Switch p2m_mem_access_check to return bool_t.
    - Use new struct npfec to pass violation info.
v3: - Add new function for updating the PTE entries, p2m_set_entry.
    - Use the new struct npfec to pass violation information.
    - Implement n2rwx, rx2rw and listener required routines.
v2: - Patch been split to ease the review process.
    - Add definitions of data abort data fetch status codes (enum dabt_dfsc)
      and only call p2m_mem_access_check for traps caused by permission violations.
    - Only call p2m_write_pte in p2m_lookup if the PTE permission actually changed.
    - Properly save settings in the Radix tree and pause the VCPU with
      mem_event_vcpu_pause.
xen/arm: Instruction prefetch abort (X) mem_event handling

Add missing structure definition for iabt and update the trap handling
mechanism to only inject the exception if the mem_access checker
decides to do so.

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
---
v4: - Don't mark instruction fetch violation as read violation.
    - Use new struct npfec to pass violation info.
v2: - Add definition for instruction abort instruction fetch status codes
       (enum iabt_ifsc) and only call p2m_mem_access_check for traps triggered
       for permission violations.
xen/arm: Enable the compilation of mem_access and mem_event on ARM.

This patch sets up the infrastructure to support mem_access and mem_event
on ARM and turns on compilation. We define the required XSM functions.

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
---
v3: Wrap mem_event related functions in XSM into #ifdef HAS_MEM_ACCESS
       blocks.
    Update XSM hooks in flask to properly wire it up on ARM.

v2: Add CONFIG_MEM_PAGING and CONFIG_MEM_SHARING definitions and
       use them instead of CONFIG_X86.
    Split domctl copy-back and p2m type definitions into separate
       patches and move this patch to the end of the series.
xen: Extend getdomaininfo to return the domain's max_gpfn

On ARM determining a domains max_gpfn thus far required the user to be aware
of how the guest's memory is mapped with potential holes and estimate the max
gpfn accordingly. Extending getdomaininfo to just return this value simplifies
the process for the user.

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
tools/libxc: Allocate magic page for mem access on ARM

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
tools/tests: Enable xen-access on ARM

On ARM the guest memory doesn't start from 0 and has multiple banks
of memory, thus we adjust the setting/unsetting routines accordingly.
We also define the ARM specific test_and_set_bit function.

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
---
v5: - Use the new information returned by getdomaininfo, max_gpfn, to
      set access permissions. On ARM this will include the potential
      memory hole as well which the hypervisor just loops over.
v4: - Take into account multiple guest ram banks on ARM.
    - Move HAS_MEM_ACCESS definition into config/*.mk and only compile
      xen-access when it is defined.
    - Pass CONFIG_X86/CONFIG_ARM flags during compilation in xen-access
      Makefile.