Whilst KVM benefits from the kernel randomisation via KASLR, there is
no additional randomisation when the kernel is running at EL1, as we
directly use a fixed offset from the linear mapping. This is not
necessarily a problem, but we could do a bit better by independently
randomizing the HYP placement.
This series proposes to randomise the offset by inserting a few random
bits between the MSB of the RAM linear mapping and the top of the HYP
VA (VA_BITS - 2). That's not a lot of random bits (on my Mustang, I
get 13 bits), but that's better than nothing.
In order to achieve this, we need to be able to patch dynamic values
in the kernel text. This results in a bunch of changes to the
alternative framework, the insn library, and a few more hacks in KVM
itself (we get a new way to map the GIC at EL2). This series used to
depend on a number of cleanups in asm-offsets, which is not the case
anymore. I'm still including them as I think they are still pretty
useful.
This has been tested on the FVP model, Seattle (both 39 and 48bit VA),
Mustang and Thunder-X. I've also done a sanity check on 32bit (which
is only impacted by the HYP IO VA stuff).
Thanks,
M.
* From v3:
- Reworked the alternative code to leave the actual patching to
the callback function. This should allow for more flexibility
should someone or something require it
- Now detects underflows in the IOVA allocator
- Moved the VA patching code to va_layout.c
* From v2:
- Fixed a crapload of bugs in the immediate generation patch
I now have a test harness for it, making sure it generates the
same thing as GAS...
- Fixed a bug in the asm-offsets.h exclusion patch
- Reworked the alternative_cb code to be nicer and avoid generating
pointless nops
* From v1:
- Now works correctly with KASLR
- Dropped the callback field from alt_instr, and reuse one of the
existing fields to store an offset to the callback
- Fix HYP teardown path (depends on fixes previously posted)
- Dropped the VA offset macros
Marc Zyngier (19):
arm64: asm-offsets: Avoid clashing DMA definitions
arm64: asm-offsets: Remove unused definitions
arm64: asm-offsets: Remove potential circular dependency
arm64: alternatives: Enforce alignment of struct alt_instr
arm64: alternatives: Add dynamic patching feature
arm64: insn: Add N immediate encoding
arm64: insn: Add encoder for bitwise operations using literals
arm64: KVM: Dynamically patch the kernel/hyp VA mask
arm64: cpufeatures: Drop the ARM64_HYP_OFFSET_LOW feature flag
KVM: arm/arm64: Do not use kern_hyp_va() with kvm_vgic_global_state
KVM: arm/arm64: Demote HYP VA range display to being a debug feature
KVM: arm/arm64: Move ioremap calls to create_hyp_io_mappings
KVM: arm/arm64: Keep GICv2 HYP VAs in kvm_vgic_global_state
KVM: arm/arm64: Move HYP IO VAs to the "idmap" range
arm64; insn: Add encoder for the EXTR instruction
arm64: insn: Allow ADD/SUB (immediate) with LSL #12
arm64: KVM: Dynamically compute the HYP VA mask
arm64: KVM: Introduce EL2 VA randomisation
arm64: Update the KVM memory map documentation
Documentation/arm64/memory.txt | 8 +-
arch/arm/include/asm/kvm_hyp.h | 6 +
arch/arm/include/asm/kvm_mmu.h | 4 +-
arch/arm64/include/asm/alternative.h | 49 ++++++--
arch/arm64/include/asm/alternative_types.h | 17 +++
arch/arm64/include/asm/asm-offsets.h | 2 +
arch/arm64/include/asm/cpucaps.h | 2 +-
arch/arm64/include/asm/insn.h | 16 +++
arch/arm64/include/asm/kvm_hyp.h | 9 ++
arch/arm64/include/asm/kvm_mmu.h | 57 ++++-----
arch/arm64/kernel/alternative.c | 43 +++++--
arch/arm64/kernel/asm-offsets.c | 17 +--
arch/arm64/kernel/cpufeature.c | 19 ---
arch/arm64/kernel/insn.c | 190 ++++++++++++++++++++++++++++-
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/va_layout.c | 144 ++++++++++++++++++++++
arch/arm64/mm/cache.S | 4 +-
include/kvm/arm_vgic.h | 12 +-
virt/kvm/arm/hyp/vgic-v2-sr.c | 12 +-
virt/kvm/arm/mmu.c | 95 +++++++++++----
virt/kvm/arm/vgic/vgic-init.c | 6 -
virt/kvm/arm/vgic/vgic-v2.c | 40 ++----
22 files changed, 589 insertions(+), 165 deletions(-)
create mode 100644 arch/arm64/include/asm/alternative_types.h
create mode 100644 arch/arm64/kvm/va_layout.c
--
2.14.2
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