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KVM: arm64: nv: Add additional trap setup for CPTR_EL2

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We need to teach KVM a couple of new tricks. CPTR_EL2 and its
VHE accessor CPACR_EL1 need to be handled specially:

- CPACR_EL1 is trapped on VHE so that we can track the TCPAC
  and TTA bits

- CPTR_EL2.{TCPAC,E0POE} are propagated from L1 to L2

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240620164653.1130714-15-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Marc Zyngier 2024-06-20 16:46:51 +00:00 committed by Oliver Upton
parent e19d533126
commit cd931bd609
1 changed files with 18 additions and 1 deletions
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19
arch/arm64/kvm/hyp/vhe/switch.c
View File

@ -87,11 +87,23 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
__activate_traps_fpsimd32(vcpu);
}
if (!vcpu_has_nv(vcpu))
goto write;
/*
* The architecture is a bit crap (what a surprise): an EL2 guest
* writing to CPTR_EL2 via CPACR_EL1 can't set any of TCPAC or TTA,
* as they are RES0 in the guest's view. To work around it, trap the
* sucker using the very same bit it can't set...
*/
if (vcpu_el2_e2h_is_set(vcpu) && is_hyp_ctxt(vcpu))
val |= CPTR_EL2_TCPAC;
/*
* Layer the guest hypervisor's trap configuration on top of our own if
* we're in a nested context.
*/
if (!vcpu_has_nv(vcpu) || is_hyp_ctxt(vcpu))
if (is_hyp_ctxt(vcpu))
goto write;
cptr = vcpu_sanitised_cptr_el2(vcpu);
@ -115,6 +127,11 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu)
if (!(SYS_FIELD_GET(CPACR_ELx, ZEN, cptr) & BIT(0)))
val &= ~CPACR_ELx_ZEN;
if (kvm_has_feat(vcpu->kvm, ID_AA64MMFR3_EL1, S2POE, IMP))
val |= cptr & CPACR_ELx_E0POE;
val |= cptr & CPTR_EL2_TCPAC;
write:
write_sysreg(val, cpacr_el1);
}