[Xen-devel] [PATCH v9 00/13] arm/mem_access: Walk guest page tables in SW

[Sergej Proskurin <proskurin@xxxxxxxxxxxxx>]

The function p2m_mem_access_check_and_get_page is called from the
function get_page_from_gva if mem_access is active and the
hardware-aided translation of the given guest virtual address (gva) into
machine address fails. That is, if the stage-2 translation tables
constrain access to the guests's page tables, hardware-assisted
translation will fail. The idea of the function
p2m_mem_access_check_and_get_page is thus to translate the given gva and
check the requested access rights in software. However, as the current
implementation of p2m_mem_access_check_and_get_page makes use of the
hardware-aided gva to ipa translation, the translation might also fail
because of reasons stated above and will become equally relevant for the
altp2m implementation on ARM.  As such, we provide a software guest
translation table walk to address the above mentioned issue.

The current version of the implementation supports translation of both
the short-descriptor as well as the long-descriptor translation table
format on ARMv7 and ARMv8 (AArch32/AArch64).

This revised version incorporates the comments of the previous patch
series, which mainly comprise minor cosmetic fixes. All changes have
been discussed with the associated maintainers and accordingly stated in
the individual patches.

The following patch series can be found on Github[0].

Cheers,
~Sergej

[0] https://github.com/sergej-proskurin/xen (branch arm-gpt-walk-v9)

Sergej Proskurin (13):
  arm/mem_access: Add and cleanup (TCR_|TTBCR_)* defines
  arm/mem_access: Add defines supporting PTs with varying page sizes
  arm/lpae: Introduce lpae_is_page helper
  arm/mem_access: Add short-descriptor pte typedefs and macros
  arm/mem_access: Introduce GV2M_EXEC permission
  arm/mem_access: Introduce BIT_ULL bit operation
  arm/mem_access: Introduce GENMASK_ULL bit operation
  arm/guest_access: Move vgic_access_guest_memory to guest_access.h
  arm/guest_access: Rename vgic_access_guest_memory
  arm/mem_access: Add software guest-page-table walk
  arm/mem_access: Add long-descriptor based gpt
  arm/mem_access: Add short-descriptor based gpt
  arm/mem_access: Walk the guest's pt in software

 xen/arch/arm/Makefile              |   1 +
 xen/arch/arm/guest_walk.c          | 636 +++++++++++++++++++++++++++++++++++++
 xen/arch/arm/guestcopy.c           |  50 +++
 xen/arch/arm/mem_access.c          |  31 +-
 xen/arch/arm/vgic-v3-its.c         |  37 +--
 xen/arch/arm/vgic.c                |  49 ---
 xen/include/asm-arm/bitops.h       |   1 +
 xen/include/asm-arm/config.h       |   2 +
 xen/include/asm-arm/guest_access.h |   4 +
 xen/include/asm-arm/guest_walk.h   |  19 ++
 xen/include/asm-arm/lpae.h         |  66 ++++
 xen/include/asm-arm/p2m.h          |   8 +-
 xen/include/asm-arm/page.h         |   1 +
 xen/include/asm-arm/processor.h    |  69 +++-
 xen/include/asm-arm/short-desc.h   | 130 ++++++++
 xen/include/asm-arm/vgic.h         |   3 -
 xen/include/asm-x86/config.h       |   2 +
 xen/include/xen/bitops.h           |   3 +
 18 files changed, 1036 insertions(+), 76 deletions(-)
 create mode 100644 xen/arch/arm/guest_walk.c
 create mode 100644 xen/include/asm-arm/guest_walk.h
 create mode 100644 xen/include/asm-arm/short-desc.h

-- 
2.13.3


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