1 // SPDX-License-Identifier: GPL-2.0
3 * arch/arm64/kvm/fpsimd.c: Guest/host FPSIMD context coordination helpers
5 * Copyright 2018 Arm Limited
6 * Author: Dave Martin <Dave.Martin@arm.com>
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/kvm_asm.h>
13 #include <asm/kvm_host.h>
14 #include <asm/kvm_mmu.h>
17 * Called on entry to KVM_RUN unless this vcpu previously ran at least
18 * once and the most recent prior KVM_RUN for this vcpu was called from
19 * the same task as current (highly likely).
21 * This is guaranteed to execute before kvm_arch_vcpu_load_fp(vcpu),
22 * such that on entering hyp the relevant parts of current are already
25 int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
29 struct thread_info *ti = ¤t->thread_info;
30 struct user_fpsimd_state *fpsimd = ¤t->thread.uw.fpsimd_state;
33 * Make sure the host task thread flags and fpsimd state are
36 ret = create_hyp_mappings(ti, ti + 1, PAGE_HYP);
40 ret = create_hyp_mappings(fpsimd, fpsimd + 1, PAGE_HYP);
44 vcpu->arch.host_thread_info = kern_hyp_va(ti);
45 vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
51 * Prepare vcpu for saving the host's FPSIMD state and loading the guest's.
52 * The actual loading is done by the FPSIMD access trap taken to hyp.
54 * Here, we just set the correct metadata to indicate that the FPSIMD
55 * state in the cpu regs (if any) belongs to current on the host.
57 * TIF_SVE is backed up here, since it may get clobbered with guest state.
58 * This flag is restored by kvm_arch_vcpu_put_fp(vcpu).
60 void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
64 vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED | KVM_ARM64_HOST_SVE_IN_USE);
65 vcpu->arch.flags |= KVM_ARM64_FP_HOST;
66 if (test_thread_flag(TIF_SVE))
67 vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE;
71 * If the guest FPSIMD state was loaded, update the host's context
72 * tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu
73 * so that they will be written back if the kernel clobbers them due to
74 * kernel-mode NEON before re-entry into the guest.
76 void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
78 WARN_ON_ONCE(!irqs_disabled());
80 if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
81 fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.gp_regs.fp_regs);
82 clear_thread_flag(TIF_FOREIGN_FPSTATE);
83 clear_thread_flag(TIF_SVE);
88 * Write back the vcpu FPSIMD regs if they are dirty, and invalidate the
89 * cpu FPSIMD regs so that they can't be spuriously reused if this vcpu
90 * disappears and another task or vcpu appears that recycles the same
91 * struct fpsimd_state.
93 void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
97 local_irq_save(flags);
99 update_thread_flag(TIF_SVE,
100 vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
102 if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
103 /* Clean guest FP state to memory and invalidate cpu view */
105 fpsimd_flush_cpu_state();
106 } else if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
107 /* Ensure user trap controls are correctly restored */
108 fpsimd_bind_task_to_cpu();
111 local_irq_restore(flags);