Files
linux/arch/arm64/tools/cpucaps
Marc Zyngier 0bc9a9e85f KVM: arm64: Work around x1e's CNTVOFF_EL2 bogosity
It appears that on Qualcomm's x1e CPU, CNTVOFF_EL2 doesn't really
work, specially with HCR_EL2.E2H=1.

A non-zero offset results in a screaming virtual timer interrupt,
to the tune of a few 100k interrupts per second on a 4 vcpu VM.
This is also evidenced by this CPU's inability to correctly run
any of the timer selftests.

The only case this doesn't break is when this register is set to 0,
which breaks VM migration.

When HCR_EL2.E2H=0, the timer seems to behave normally, and does
not result in an interrupt storm.

As a workaround, use the fact that this CPU implements FEAT_ECV,
and trap all accesses to the virtual timer and counter, keeping
CNTVOFF_EL2 set to zero, and emulate accesses to CVAL/TVAL/CTL
and the counter itself, fixing up the timer to account for the
missing offset.

And if you think this is disgusting, you'd probably be right.

Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241217142321.763801-12-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
2025-01-02 19:19:10 +00:00

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# SPDX-License-Identifier: GPL-2.0
#
# Internal CPU capabilities constants, keep this list sorted
ALWAYS_BOOT
ALWAYS_SYSTEM
BTI
# Unreliable: use system_supports_32bit_el0() instead.
HAS_32BIT_EL0_DO_NOT_USE
HAS_32BIT_EL1
HAS_ADDRESS_AUTH
HAS_ADDRESS_AUTH_ARCH_QARMA3
HAS_ADDRESS_AUTH_ARCH_QARMA5
HAS_ADDRESS_AUTH_IMP_DEF
HAS_AMU_EXTN
HAS_ARMv8_4_TTL
HAS_CACHE_DIC
HAS_CACHE_IDC
HAS_CNP
HAS_CRC32
HAS_DCPODP
HAS_DCPOP
HAS_DIT
HAS_E0PD
HAS_ECV
HAS_ECV_CNTPOFF
HAS_EPAN
HAS_EVT
HAS_FPMR
HAS_FGT
HAS_FPSIMD
HAS_GCS
HAS_GENERIC_AUTH
HAS_GENERIC_AUTH_ARCH_QARMA3
HAS_GENERIC_AUTH_ARCH_QARMA5
HAS_GENERIC_AUTH_IMP_DEF
HAS_GIC_CPUIF_SYSREGS
HAS_GIC_PRIO_MASKING
HAS_GIC_PRIO_RELAXED_SYNC
HAS_HCR_NV1
HAS_HCX
HAS_LDAPR
HAS_LPA2
HAS_LSE_ATOMICS
HAS_MOPS
HAS_NESTED_VIRT
HAS_PAN
HAS_S1PIE
HAS_S1POE
HAS_RAS_EXTN
HAS_RNG
HAS_SB
HAS_STAGE2_FWB
HAS_TCR2
HAS_TIDCP1
HAS_TLB_RANGE
HAS_VA52
HAS_VIRT_HOST_EXTN
HAS_WFXT
HAFT
HW_DBM
KVM_HVHE
KVM_PROTECTED_MODE
MISMATCHED_CACHE_TYPE
MPAM
MPAM_HCR
MTE
MTE_ASYMM
SME
SME_FA64
SME2
SPECTRE_V2
SPECTRE_V3A
SPECTRE_V4
SPECTRE_BHB
SSBS
SVE
UNMAP_KERNEL_AT_EL0
WORKAROUND_834220
WORKAROUND_843419
WORKAROUND_845719
WORKAROUND_858921
WORKAROUND_1418040
WORKAROUND_1463225
WORKAROUND_1508412
WORKAROUND_1542419
WORKAROUND_1742098
WORKAROUND_1902691
WORKAROUND_2038923
WORKAROUND_2064142
WORKAROUND_2077057
WORKAROUND_2457168
WORKAROUND_2645198
WORKAROUND_2658417
WORKAROUND_AMPERE_AC03_CPU_38
WORKAROUND_TRBE_OVERWRITE_FILL_MODE
WORKAROUND_TSB_FLUSH_FAILURE
WORKAROUND_TRBE_WRITE_OUT_OF_RANGE
WORKAROUND_CAVIUM_23154
WORKAROUND_CAVIUM_27456
WORKAROUND_CAVIUM_30115
WORKAROUND_CAVIUM_TX2_219_PRFM
WORKAROUND_CAVIUM_TX2_219_TVM
WORKAROUND_CLEAN_CACHE
WORKAROUND_DEVICE_LOAD_ACQUIRE
WORKAROUND_NVIDIA_CARMEL_CNP
WORKAROUND_QCOM_FALKOR_E1003
WORKAROUND_QCOM_ORYON_CNTVOFF
WORKAROUND_REPEAT_TLBI
WORKAROUND_SPECULATIVE_AT
WORKAROUND_SPECULATIVE_SSBS
WORKAROUND_SPECULATIVE_UNPRIV_LOAD