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152 lines
4.3 KiB
152 lines
4.3 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* arch/arm64/kvm/fpsimd.c: Guest/host FPSIMD context coordination helpers |
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* |
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* Copyright 2018 Arm Limited |
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* Author: Dave Martin <[email protected]> |
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*/ |
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#include <linux/irqflags.h> |
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#include <linux/sched.h> |
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#include <linux/thread_info.h> |
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#include <linux/kvm_host.h> |
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#include <asm/fpsimd.h> |
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#include <asm/kvm_asm.h> |
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#include <asm/kvm_hyp.h> |
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#include <asm/kvm_mmu.h> |
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#include <asm/sysreg.h> |
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/* |
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* Called on entry to KVM_RUN unless this vcpu previously ran at least |
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* once and the most recent prior KVM_RUN for this vcpu was called from |
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* the same task as current (highly likely). |
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* |
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* This is guaranteed to execute before kvm_arch_vcpu_load_fp(vcpu), |
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* such that on entering hyp the relevant parts of current are already |
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* mapped. |
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*/ |
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int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu) |
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{ |
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int ret; |
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struct thread_info *ti = ¤t->thread_info; |
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struct user_fpsimd_state *fpsimd = ¤t->thread.uw.fpsimd_state; |
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/* |
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* Make sure the host task thread flags and fpsimd state are |
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* visible to hyp: |
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*/ |
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ret = create_hyp_mappings(ti, ti + 1, PAGE_HYP); |
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if (ret) |
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goto error; |
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ret = create_hyp_mappings(fpsimd, fpsimd + 1, PAGE_HYP); |
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if (ret) |
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goto error; |
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if (vcpu->arch.sve_state) { |
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void *sve_end; |
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sve_end = vcpu->arch.sve_state + vcpu_sve_state_size(vcpu); |
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ret = create_hyp_mappings(vcpu->arch.sve_state, sve_end, |
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PAGE_HYP); |
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if (ret) |
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goto error; |
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} |
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vcpu->arch.host_thread_info = kern_hyp_va(ti); |
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vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd); |
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error: |
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return ret; |
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} |
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/* |
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* Prepare vcpu for saving the host's FPSIMD state and loading the guest's. |
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* The actual loading is done by the FPSIMD access trap taken to hyp. |
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* |
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* Here, we just set the correct metadata to indicate that the FPSIMD |
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* state in the cpu regs (if any) belongs to current on the host. |
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* |
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* TIF_SVE is backed up here, since it may get clobbered with guest state. |
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* This flag is restored by kvm_arch_vcpu_put_fp(vcpu). |
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*/ |
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void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) |
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{ |
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BUG_ON(!current->mm); |
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vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED | |
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KVM_ARM64_HOST_SVE_IN_USE | |
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KVM_ARM64_HOST_SVE_ENABLED); |
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vcpu->arch.flags |= KVM_ARM64_FP_HOST; |
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if (test_thread_flag(TIF_SVE)) |
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vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE; |
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if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) |
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vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED; |
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} |
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/* |
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* If the guest FPSIMD state was loaded, update the host's context |
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* tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu |
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* so that they will be written back if the kernel clobbers them due to |
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* kernel-mode NEON before re-entry into the guest. |
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*/ |
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void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) |
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{ |
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WARN_ON_ONCE(!irqs_disabled()); |
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if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) { |
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fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.fp_regs, |
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vcpu->arch.sve_state, |
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vcpu->arch.sve_max_vl); |
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clear_thread_flag(TIF_FOREIGN_FPSTATE); |
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update_thread_flag(TIF_SVE, vcpu_has_sve(vcpu)); |
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} |
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} |
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/* |
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* Write back the vcpu FPSIMD regs if they are dirty, and invalidate the |
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* cpu FPSIMD regs so that they can't be spuriously reused if this vcpu |
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* disappears and another task or vcpu appears that recycles the same |
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* struct fpsimd_state. |
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*/ |
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void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) |
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{ |
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unsigned long flags; |
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bool host_has_sve = system_supports_sve(); |
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bool guest_has_sve = vcpu_has_sve(vcpu); |
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local_irq_save(flags); |
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if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) { |
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if (guest_has_sve) { |
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__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR); |
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/* Restore the VL that was saved when bound to the CPU */ |
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if (!has_vhe()) |
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sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, |
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SYS_ZCR_EL1); |
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} |
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fpsimd_save_and_flush_cpu_state(); |
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} else if (has_vhe() && host_has_sve) { |
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/* |
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* The FPSIMD/SVE state in the CPU has not been touched, and we |
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* have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been |
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* reset to CPACR_EL1_DEFAULT by the Hyp code, disabling SVE |
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* for EL0. To avoid spurious traps, restore the trap state |
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* seen by kvm_arch_vcpu_load_fp(): |
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*/ |
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if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED) |
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sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN); |
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else |
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sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0); |
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} |
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update_thread_flag(TIF_SVE, |
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vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE); |
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local_irq_restore(flags); |
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}
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