From beed09067b428a7e84a53b05c1de1f93c8460e91 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 17 Mar 2021 16:50:39 +0000 Subject: [PATCH] KVM: arm64: Trap host SVE accesses when the FPSIMD state is dirty ZCR_EL2 controls the upper bound for ZCR_EL1, and is set to a potentially lower limit when the guest uses SVE. In order to restore the SVE state on the EL1 host, we must first reset ZCR_EL2 to its original value. To make it as lazy as possible on the EL1 host side, set the SVE trapping in place when exiting from the guest. On the first EL1 access to SVE, ZCR_EL2 will be restored to its full glory. Suggested-by: Andrew Scull Acked-by: Will Deacon Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 4 ++++ arch/arm64/kvm/hyp/nvhe/switch.c | 9 +++++++-- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index f012f86..8d04d69 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -177,6 +177,10 @@ void handle_trap(struct kvm_cpu_context *host_ctxt) case ESR_ELx_EC_SMC64: handle_host_smc(host_ctxt); break; + case ESR_ELx_EC_SVE: + sve_cond_update_zcr_vq(ZCR_ELx_LEN_MASK, SYS_ZCR_EL2); + sysreg_clear_set(cptr_el2, CPTR_EL2_TZ, 0); + break; default: hyp_panic(); } diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index f3d0e9e..60adc7f 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -68,7 +68,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu) static void __deactivate_traps(struct kvm_vcpu *vcpu) { extern char __kvm_hyp_host_vector[]; - u64 mdcr_el2; + u64 mdcr_el2, cptr; ___deactivate_traps(vcpu); @@ -101,7 +101,12 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu) write_sysreg(HCR_HOST_NVHE_PROTECTED_FLAGS, hcr_el2); else write_sysreg(HCR_HOST_NVHE_FLAGS, hcr_el2); - write_sysreg(CPTR_EL2_DEFAULT, cptr_el2); + + cptr = CPTR_EL2_DEFAULT; + if (vcpu_has_sve(vcpu) && (vcpu->arch.flags & KVM_ARM64_FP_ENABLED)) + cptr |= CPTR_EL2_TZ; + + write_sysreg(cptr, cptr_el2); write_sysreg(__kvm_hyp_host_vector, vbar_el2); } -- 2.7.4