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arm64: Add the arm64.nosve command line option

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In order to be able to completely disable SVE even if the HW
seems to support it (most likely because the FW is broken),
move the SVE setup into the EL2 finalisation block, and
use a new idreg override to deal with it.

Note that we also nuke id_aa64zfr0_el1 as a byproduct, and
that SME also gets disabled, due to the dependency between the
two features.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220630160500.1536744-9-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Marc Zyngier
2022-06-30 17:04:59 +01:00
committed by Will Deacon
parent b3000e2133
commit 504ee23611
6 changed files with 48 additions and 17 deletions
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11
arch/arm64/kernel/hyp-stub.S
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@@ -98,6 +98,17 @@ SYM_CODE_START_LOCAL(elx_sync)
SYM_CODE_END(elx_sync)
SYM_CODE_START_LOCAL(__finalise_el2)
check_override id_aa64pfr0 ID_AA64PFR0_SVE_SHIFT .Linit_sve .Lskip_sve
.Linit_sve: /* SVE register access */
mrs x0, cptr_el2 // Disable SVE traps
bic x0, x0, #CPTR_EL2_TZ
msr cptr_el2, x0
isb
mov x1, #ZCR_ELx_LEN_MASK // SVE: Enable full vector
msr_s SYS_ZCR_EL2, x1 // length for EL1.
.Lskip_sve:
check_override id_aa64pfr1 ID_AA64PFR1_SME_SHIFT .Linit_sme .Lskip_sme
.Linit_sme: /* SME register access and priority mapping */