linux-kernel - [PATCH 00/11] arm64: ptdump: View the host stage-2 page-tables

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Date:   Wed, 27 Sep 2023 11:25:06 +0000
From:   Sebastian Ene <sebastianene@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com, will@...nel.org, ryan.roberts@....com,
        mark.rutland@....com, maz@...nel.org, vdonnefort@...gle.com,
        Sebastian Ene <sebastianene@...gle.com>
Subject: [PATCH 00/11] arm64: ptdump: View the host stage-2 page-tables

Hi,

This can be used as a debugging tool for dumping the host stage-2
page-tables under pKVM envinronment.

When CONFIG_NVHE_EL2_PTDUMP_DEBUGFS is enabled, ptdump registers the
'host_stage2_kernel_page_tables' entry with debugfs and this allows us
to dump the host stage-2 page-tables with the following command:
cat /sys/kernel/debug/host_stage2_kernel_page_tables

The output is showing the entries in the following format:
<IPA range> <size> <descriptor type> <access permissions> <mem_attributes>

The tool interprets the pKVM ownership annotation stored in the invalid
entries and dumps to the console the ownership information. To be able
to access the host stage-2 page-tables from the kernel, a new hypervisor
call was introduced which allows us to snapshot the page-tables in a host
provided buffer. The hypervisor call is hidden behind CONFIG_NVHE_EL2_DEBUG
as this should be used under debugging environment.

I verified this series with Qemu and Pixel 6 both using kvm-arm.mode=protected.

Thanks,

Sebastian Ene (11):
  KVM: arm64: Add snap shooting the host stage-2 pagetables
  arm64: ptdump: Use the mask from the state structure
  arm64: ptdump: Add the walker function to the ptdump info structure
  KVM: arm64: Move pagetable definitions to common header
  arm64: ptdump: Introduce stage-2 pagetables format description
  arm64: ptdump: Register a debugfs entry for the host stage-2
    page-tables
  arm64: ptdump: Snapshot the host stage-2 pagetables
  arm64: ptdump: Parse the host stage-2 page-tables from the snapshot
  arm64: ptdump: Interpret memory attributes based on runtime
    configuration
  arm64: ptdump: Interpret pKVM ownership annotations
  arm64: ptdump: Fix format output during stage-2 pagetable dumping

 arch/arm64/include/asm/kvm_asm.h              |   1 +
 arch/arm64/include/asm/kvm_pgtable.h          |  85 ++++
 arch/arm64/include/asm/ptdump.h               |   6 +
 arch/arm64/kvm/Kconfig                        |  12 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |   8 +-
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  18 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 103 +++++
 arch/arm64/kvm/hyp/pgtable.c                  |  98 +++--
 arch/arm64/mm/ptdump.c                        | 405 +++++++++++++++++-
 arch/arm64/mm/ptdump_debugfs.c                |  37 +-
 10 files changed, 716 insertions(+), 57 deletions(-)

-- 
2.42.0.515.g380fc7ccd1-goog