diff options
| -rw-r--r-- | arch/arm64/kvm/hyp/vhe/switch.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index f4ce892edcd6..fa6c27b6ad99 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -67,6 +67,8 @@ static u64 __compute_hcr(struct kvm_vcpu *vcpu) static void __activate_cptr_traps(struct kvm_vcpu *vcpu) { + u64 cptr; + /* * With VHE (HCR.E2H == 1), accesses to CPACR_EL1 are routed to * CPTR_EL2. In general, CPACR_EL1 has the same layout as CPTR_EL2, @@ -85,6 +87,35 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu) __activate_traps_fpsimd32(vcpu); } + /* + * 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)) + goto write; + + cptr = vcpu_sanitised_cptr_el2(vcpu); + + /* + * Pay attention, there's some interesting detail here. + * + * The CPTR_EL2.xEN fields are 2 bits wide, although there are only two + * meaningful trap states when HCR_EL2.TGE = 0 (running a nested guest): + * + * - CPTR_EL2.xEN = x0, traps are enabled + * - CPTR_EL2.xEN = x1, traps are disabled + * + * In other words, bit[0] determines if guest accesses trap or not. In + * the interest of simplicity, clear the entire field if the guest + * hypervisor has traps enabled to dispel any illusion of something more + * complicated taking place. + */ + if (!(SYS_FIELD_GET(CPACR_ELx, FPEN, cptr) & BIT(0))) + val &= ~CPACR_ELx_FPEN; + if (!(SYS_FIELD_GET(CPACR_ELx, ZEN, cptr) & BIT(0))) + val &= ~CPACR_ELx_ZEN; + +write: write_sysreg(val, cpacr_el1); } |