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KVM: arm64: Simplify handling of ARCH_WORKAROUND_2

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Owing to the fact that the host kernel is always mitigated, we can
drastically simplify the WA2 handling by keeping the mitigation
state ON when entering the guest. This means the guest is either
unaffected or not mitigated.

This results in a nice simplification of the mitigation space,
and the removal of a lot of code that was never really used anyway.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Marc Zyngier 2020-09-18 12:25:40 +01:00 • committed by Will Deacon
parent c28762070c
commit 29e8910a56
14 changed files with 41 additions and 163 deletions
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14
arch/arm64/kernel/cpu_errata.c
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@ -108,20 +108,6 @@ cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *cap)
int ssbd_state __read_mostly = ARM64_SSBD_UNKNOWN;
void __init arm64_enable_wa2_handling(struct alt_instr *alt,
__le32 *origptr, __le32 *updptr,
int nr_inst)
{
BUG_ON(nr_inst != 1);
/*
* Only allow mitigation on EL1 entry/exit and guest
* ARCH_WORKAROUND_2 handling if the SSBD state allows it to
* be flipped.
*/
if (arm64_get_ssbd_state() == ARM64_SSBD_KERNEL)
*updptr = cpu_to_le32(aarch64_insn_gen_nop());
}
#ifdef CONFIG_ARM64_ERRATUM_1463225
DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);