[PATCH 00/12] arm64: Add support for FEAT_E2H0, or lack thereof
Marc Zyngier
maz at kernel.org
Mon Nov 13 09:42:32 PST 2023
Since ARMv8.1, the architecture has grown the VHE feature, which makes
EL2 a superset of EL1. With ARMv9.5 (and retroactively allowed from
ARMv8.1), the architecture allows implementations to have VHE as the
*only* implemented behaviour, meaning that HCR_EL2.E2H can be
implemented as RES1. As a follow-up, HCR_EL2.NV1 can also be
implemented as RES0, making the VHE-ness of the architecture
recursive.
This has a number of consequences, both at boot time and for KVM,
though the changes at that level are pretty minor.
The real meat of this series is on the cpufeature front, as FEAT_E2H0
is a *negative* feature, where 0b1111 (-1) represents E2H being RES1
and 0b1110 (-2) additionally indicates that NV1 is RES0. Fun, isn't
it?
As a bonus, a popular crop of non-compliant HW gets promoted as the
first batch of non-zero E2H0 users, making things easy for KVM.
This series is a prefix for the next drop of NV support.
Marc Zyngier (12):
arm64: cpufeatures: Correctly handle signed values
arm64: cpufeature: Correctly display signed override values
arm64: sysreg: Add layout for ID_AA64MMFR4_EL1
arm64: cpufeature: Add ID_AA64MMFR4_EL1 handling
arm64: cpufeature: Detect E2H0 not being implemented
arm64: cpufeature: Detect HCR_EL2.NV1 being RES0
arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is
non-zero
arm64: Add override for ID_AA64MMFR4_EL1.E2H0
arm64: Add MIDR-based override infrastructure
arm64: Add MIDR-based overrides for ID_AA64MMFR4_EL1.E2H0
KVM: arm64: Expose ID_AA64MMFR4_EL1 to guests
KVM: arm64: Force guest's HCR_EL2.E2H RES1 when NV1 is not implemented
arch/arm64/include/asm/cpu.h | 1 +
arch/arm64/include/asm/cpufeature.h | 2 +
arch/arm64/include/asm/kvm_emulate.h | 3 +-
arch/arm64/kernel/cpufeature.c | 92 +++++++++++++++++++++++++---
arch/arm64/kernel/cpuinfo.c | 1 +
arch/arm64/kernel/head.S | 25 +++++---
arch/arm64/kernel/idreg-override.c | 65 ++++++++++++++++++++
arch/arm64/kvm/nested.c | 4 ++
arch/arm64/kvm/sys_regs.c | 14 ++++-
arch/arm64/tools/cpucaps | 2 +
arch/arm64/tools/sysreg | 37 +++++++++++
11 files changed, 225 insertions(+), 21 deletions(-)
--
2.39.2
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