[PATCH v10 0/5] arm64: ptdump: View the second stage page-tables
From: Sebastian Ene
Date: Mon Sep 09 2024 - 08:47:47 EST
Hi,
This series extends the ptdump support to allow dumping the guest
stage-2 pagetables. When CONFIG_PTDUMP_STAGE2_DEBUGFS is enabled, ptdump
registers the new following files under debugfs:
- /sys/debug/kvm/<guest_id>/stage2_page_tables
- /sys/debug/kvm/<guest_id>/stage2_levels
- /sys/debug/kvm/<guest_id>/ipa_range
This allows userspace tools (eg. cat) to dump the stage-2 pagetables by
reading the 'stage2_page_tables' file.
The output format has the following fields:
<IPA range> <size> <level> <access permissions> <mem_attributes>
Below is the output of a guest stage-2 pagetable dump running under Qemu.
After a VM is created, the following files are available:
# cat /sys/kernel/debug/kvm/256-4/stage2_levels
4
# cat /sys/kernel/debug/kvm/256-4/ipa_range
44
# cat /sys/kernel/debug/kvm/256-4/stage2_page_tables
---[ Guest IPA ]---
0x0000000000000000-0x0000000001000000 16M 2
0x0000000001000000-0x0000000001020000 128K 3
0x0000000001020000-0x0000000001021000 4K 3 R W X AF
0x0000000001021000-0x0000000001200000 1916K 3
0x0000000001200000-0x0000000040000000 1006M 2
0x0000000040000000-0x0000000080000000 1G 0
0x0000000080000000-0x0000000081200000 18M 2 R W AF BLK
0x0000000081200000-0x0000000081a00000 8M 2 R W X AF BLK
0x0000000081a00000-0x0000000081c00000 2M 2 R W AF BLK
0x0000000081c00000-0x0000000082200000 6M 2 R W X AF BLK
0x0000000082200000-0x0000000082400000 2M 2 R W AF BLK
0x0000000082400000-0x0000000082800000 4M 2 R W X AF BLK
0x0000000082800000-0x0000000082a00000 2M 2 R W AF BLK
0x0000000082a00000-0x0000000082c00000 2M 2
0x0000000082c00000-0x0000000083200000 6M 2 R W X AF BLK
0x0000000083200000-0x0000000083400000 2M 2
0x0000000083400000-0x0000000083a00000 6M 2 R W X AF BLK
0x0000000083a00000-0x000000008fe00000 196M 2
0x000000008fe00000-0x0000000090000000 2M 2 R W AF BLK
0x0000000090000000-0x0000000099400000 148M 2
0x0000000099400000-0x0000000099600000 2M 2 R W X AF BLK
0x0000000099600000-0x000000009b600000 32M 2
0x000000009b600000-0x000000009be00000 8M 2 R W X AF BLK
0x000000009be00000-0x000000009c000000 2M 2 R W AF BLK
0x000000009c000000-0x00000000c0000000 576M 2
Changelog:
v9 -> current:
* fixed an issue reported by Mark - when using CONFIG_ARM64_VA_BITS=47
and CONFIG_PAGE_SIZE_16KB=y ptdump was entering a check used for
kernel pagetables to interpret the folded levels, thus overriding the
current page table level. This was resulting in bogus output when ran
on the stage-2 pagetables.
* folded the Kconfig patch in the one that introduces kvm/ptdump.c as
suggested by Vincent. Collected Vincent's Reviewed-by tag, thanks.
* applied Mark's sugegstion to use the callbacks by construct when
interpretting the level and the ipa_bits instead of a string
comparison on the pseudo-file.
* fixed a bunch of nits
v8 -> v9:
* squashed the last 3 patches and separated the Kconfig change as the
last patch.
* updated the commit message of the 3rd patch
* printing level numbers instead of names as suggested by Mark
* fixed one return code to ERR_PTR(-ENOMEM) as spotted by Vincent
* dropped a barely empty header 'kvm_ptdump.h'
* general cosmetic changes
v7 -> v8:
* applied Will's feedback and prefixed the exported structure names
with ptdump_
* dropped PTE_CONT and PTE_NG attribute parsing from Oliver's
suggestion
* fixed spurious BLK annotation reported by Vincent
* repurposed `stage2_levels` debugfs file to show the number of the
levels
* tried changing the order of the patches:
"5/6 Initialize the ptdump parser with stage-2 attributes" before
exposing the debugfs file but ended up keeping the same order
as this depends on the later one.
v6 -> v7:
* Reworded commit for this patch : [PATCH v6 2/6] arm64: ptdump: Expose
the attribute parsing functionality
* fixed minor conflicts in the struct pg_state definition
* moved the kvm_ptdump_guest_registration in the
* kvm_arch_create_vm_debugfs
* reset the parse state before walking the pagetables
* copy the level name to the pg_level buffer
v5 -> v6:
* don't return an error if the kvm_arch_create_vm_debugfs fails to
initialize (ref.
https://lore.kernel.org/all/20240216155941.2029458-1-oliver.upton@xxxxxxxxx/)
* fix use-after-free suggested by getting a reference to the
KVM struct while manipulating the debugfs files
and put the reference on the file close.
* do all the allocations at once for the ptdump parser state tracking
and simplify the initialization.
* move the ptdump parser state initialization as part of the file_open
* create separate files for printing the guest stage-2 pagetable
configuration such as: the start level of the pagetable walk and the
number of bits used for the IPA space representation.
* fixed the wrong header format for the newly added file
* include missing patch which hasn't been posted on the v5:
"KVM-arm64-Move-pagetable-definitions-to-common-heade.patch"
Links to previous versions:
v9:
https://lore.kernel.org/all/20240827084549.45731-1-sebastianene@xxxxxxxxxx/
v8:
https://lore.kernel.org/all/20240816123906.3683425-1-sebastianene@xxxxxxxxxx/
v7:
https://lore.kernel.org/all/20240621123230.1085265-1-sebastianene@xxxxxxxxxx/
v6:
https://lore.kernel.org/all/20240220151035.327199-1-sebastianene@xxxxxxxxxx/
v5:
https://lore.kernel.org/all/20240207144832.1017815-2-sebastianene@xxxxxxxxxx/
Thanks,
Sebastian
Sebastian Ene (5):
KVM: arm64: Move pagetable definitions to common header
arm64: ptdump: Expose the attribute parsing functionality
arm64: ptdump: Use the ptdump description from a local context
arm64: ptdump: Don't override the level when operating on the stage-2
tables
KVM: arm64: Register ptdump with debugfs on guest creation
arch/arm64/include/asm/kvm_host.h | 6 +
arch/arm64/include/asm/kvm_pgtable.h | 42 +++++
arch/arm64/include/asm/ptdump.h | 42 ++++-
arch/arm64/kvm/Kconfig | 17 ++
arch/arm64/kvm/Makefile | 1 +
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/hyp/pgtable.c | 42 -----
arch/arm64/kvm/ptdump.c | 268 +++++++++++++++++++++++++++
arch/arm64/mm/ptdump.c | 70 ++-----
9 files changed, 396 insertions(+), 93 deletions(-)
create mode 100644 arch/arm64/kvm/ptdump.c
--
2.46.0.469.g59c65b2a67-goog