1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * arch/arm64/kvm/fpsimd.c: Guest/host FPSIMD context coordination helpers 4 * 5 * Copyright 2018 Arm Limited 6 * Author: Dave Martin <Dave.Martin@arm.com> 7 */ 8 #include <linux/irqflags.h> 9 #include <linux/sched.h> 10 #include <linux/thread_info.h> 11 #include <linux/kvm_host.h> 12 #include <asm/fpsimd.h> 13 #include <asm/kvm_asm.h> 14 #include <asm/kvm_hyp.h> 15 #include <asm/kvm_mmu.h> 16 #include <asm/sysreg.h> 17 18 /* 19 * Called on entry to KVM_RUN unless this vcpu previously ran at least 20 * once and the most recent prior KVM_RUN for this vcpu was called from 21 * the same task as current (highly likely). 22 * 23 * This is guaranteed to execute before kvm_arch_vcpu_load_fp(vcpu), 24 * such that on entering hyp the relevant parts of current are already 25 * mapped. 26 */ 27 int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu) 28 { 29 int ret; 30 31 struct thread_info *ti = ¤t->thread_info; 32 struct user_fpsimd_state *fpsimd = ¤t->thread.uw.fpsimd_state; 33 34 /* 35 * Make sure the host task thread flags and fpsimd state are 36 * visible to hyp: 37 */ 38 ret = create_hyp_mappings(ti, ti + 1, PAGE_HYP); 39 if (ret) 40 goto error; 41 42 ret = create_hyp_mappings(fpsimd, fpsimd + 1, PAGE_HYP); 43 if (ret) 44 goto error; 45 46 if (vcpu->arch.sve_state) { 47 void *sve_end; 48 49 sve_end = vcpu->arch.sve_state + vcpu_sve_state_size(vcpu); 50 51 ret = create_hyp_mappings(vcpu->arch.sve_state, sve_end, 52 PAGE_HYP); 53 if (ret) 54 goto error; 55 } 56 57 vcpu->arch.host_thread_info = kern_hyp_va(ti); 58 vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd); 59 error: 60 return ret; 61 } 62 63 /* 64 * Prepare vcpu for saving the host's FPSIMD state and loading the guest's. 65 * The actual loading is done by the FPSIMD access trap taken to hyp. 66 * 67 * Here, we just set the correct metadata to indicate that the FPSIMD 68 * state in the cpu regs (if any) belongs to current on the host. 69 * 70 * TIF_SVE is backed up here, since it may get clobbered with guest state. 71 * This flag is restored by kvm_arch_vcpu_put_fp(vcpu). 72 */ 73 void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) 74 { 75 BUG_ON(!current->mm); 76 77 vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED | 78 KVM_ARM64_HOST_SVE_IN_USE | 79 KVM_ARM64_HOST_SVE_ENABLED); 80 vcpu->arch.flags |= KVM_ARM64_FP_HOST; 81 82 if (test_thread_flag(TIF_SVE)) 83 vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE; 84 85 if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) 86 vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED; 87 } 88 89 /* 90 * If the guest FPSIMD state was loaded, update the host's context 91 * tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu 92 * so that they will be written back if the kernel clobbers them due to 93 * kernel-mode NEON before re-entry into the guest. 94 */ 95 void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) 96 { 97 WARN_ON_ONCE(!irqs_disabled()); 98 99 if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) { 100 fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.fp_regs, 101 vcpu->arch.sve_state, 102 vcpu->arch.sve_max_vl); 103 104 clear_thread_flag(TIF_FOREIGN_FPSTATE); 105 update_thread_flag(TIF_SVE, vcpu_has_sve(vcpu)); 106 } 107 } 108 109 /* 110 * Write back the vcpu FPSIMD regs if they are dirty, and invalidate the 111 * cpu FPSIMD regs so that they can't be spuriously reused if this vcpu 112 * disappears and another task or vcpu appears that recycles the same 113 * struct fpsimd_state. 114 */ 115 void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) 116 { 117 unsigned long flags; 118 bool host_has_sve = system_supports_sve(); 119 bool guest_has_sve = vcpu_has_sve(vcpu); 120 121 local_irq_save(flags); 122 123 if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) { 124 if (guest_has_sve) { 125 __vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR); 126 127 /* Restore the VL that was saved when bound to the CPU */ 128 if (!has_vhe()) 129 sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, 130 SYS_ZCR_EL1); 131 } 132 133 fpsimd_save_and_flush_cpu_state(); 134 } else if (has_vhe() && host_has_sve) { 135 /* 136 * The FPSIMD/SVE state in the CPU has not been touched, and we 137 * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been 138 * reset to CPACR_EL1_DEFAULT by the Hyp code, disabling SVE 139 * for EL0. To avoid spurious traps, restore the trap state 140 * seen by kvm_arch_vcpu_load_fp(): 141 */ 142 if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED) 143 sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN); 144 else 145 sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0); 146 } 147 148 update_thread_flag(TIF_SVE, 149 vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE); 150 151 local_irq_restore(flags); 152 } 153