[PATCH 00/20] KVM: arm64: Generalise RESx handling
Marc Zyngier
maz at kernel.org
Mon Jan 26 04:16:34 PST 2026
Having spent some time dealing with some dark corners of the
architecture, I have realised that our RESx handling is a bit patchy.
Specially when it comes to RES1 bits, which are not clearly defined in
config.c, and rely on band-aids such as FIXED_VALUE.
This series takes the excuse of adding SCTLR_EL2 sanitisation to bite
the bullet and pursue several goals:
- clearly define bits that are RES1 when a feature is absent
- have a unified data structure to manage both RES0 and RES1 bits
- deal with the annoying complexity of some features being
conditioned on E2H==1
- allow a single bit to take different RESx values depending on the
value of E2H
This allows quite a bit of cleanup, including the total removal of the
FIXED_VALUE horror, which was always a bizarre construct. We also get
a new debugfs file to introspect the RESx settings for a given guest.
Overall, this lowers the complexity of expressing the configuration
constraints, for very little code (most of the extra lines are
introduced by the debugfs stuff, and SCTLR_EL2 being added to the
sysreg file).
Patches on top of my kvm-arm64/vtcr branch (which is currently
simmering in -next).
Marc Zyngier (20):
arm64: Convert SCTLR_EL2 to sysreg infrastructure
KVM: arm64: Remove duplicate configuration for SCTLR_EL1.{EE,E0E}
KVM: arm64: Introduce standalone FGU computing primitive
KVM: arm64: Introduce data structure tracking both RES0 and RES1 bits
KVM: arm64: Extend unified RESx handling to runtime sanitisation
KVM: arm64: Inherit RESx bits from FGT register descriptors
KVM: arm64: Allow RES1 bits to be inferred from configuration
KVM: arm64: Correctly handle SCTLR_EL1 RES1 bits for unsupported
features
KVM: arm64: Convert HCR_EL2.RW to AS_RES1
KVM: arm64: Simplify FIXED_VALUE handling
KVM: arm64: Add REQUIRES_E2H1 constraint as configuration flags
KVM: arm64: Add RESx_WHEN_E2Hx constraints as configuration flags
KVM: arm64: Move RESx into individual register descriptors
KVM: arm64: Simplify handling of HCR_EL2.E2H RESx
KVM: arm64: Get rid of FIXED_VALUE altogether
KVM: arm64: Simplify handling of full register invalid constraint
KVM: arm64: Remove all traces of FEAT_TME
KVM: arm64: Remove all traces of HCR_EL2.MIOCNCE
KVM: arm64: Add sanitisation to SCTLR_EL2
KVM: arm64: Add debugfs file dumping computed RESx values
arch/arm64/include/asm/kvm_host.h | 33 +-
arch/arm64/include/asm/sysreg.h | 7 -
arch/arm64/kvm/config.c | 430 ++++++++++--------
arch/arm64/kvm/emulate-nested.c | 10 +-
arch/arm64/kvm/nested.c | 151 +++---
arch/arm64/kvm/sys_regs.c | 98 ++++
arch/arm64/tools/sysreg | 82 +++-
tools/arch/arm64/include/asm/sysreg.h | 6 -
tools/perf/Documentation/perf-arm-spe.txt | 1 -
.../testing/selftests/kvm/arm64/set_id_regs.c | 1 -
10 files changed, 510 insertions(+), 309 deletions(-)
--
2.47.3
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