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205 lines
6.1 KiB
205 lines
6.1 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/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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void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu) |
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{ |
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struct task_struct *p = vcpu->arch.parent_task; |
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struct user_fpsimd_state *fpsimd; |
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if (!is_protected_kvm_enabled() || !p) |
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return; |
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fpsimd = &p->thread.uw.fpsimd_state; |
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kvm_unshare_hyp(fpsimd, fpsimd + 1); |
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put_task_struct(p); |
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} |
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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 user_fpsimd_state *fpsimd = ¤t->thread.uw.fpsimd_state; |
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kvm_vcpu_unshare_task_fp(vcpu); |
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/* Make sure the host task fpsimd state is visible to hyp: */ |
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ret = kvm_share_hyp(fpsimd, fpsimd + 1); |
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if (ret) |
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return ret; |
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vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd); |
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/* |
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* We need to keep current's task_struct pinned until its data has been |
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* unshared with the hypervisor to make sure it is not re-used by the |
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* kernel and donated to someone else while already shared -- see |
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* kvm_vcpu_unshare_task_fp() for the matching put_task_struct(). |
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*/ |
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if (is_protected_kvm_enabled()) { |
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get_task_struct(current); |
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vcpu->arch.parent_task = current; |
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} |
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return 0; |
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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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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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BUG_ON(test_thread_flag(TIF_SVE)); |
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if (!system_supports_fpsimd()) |
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return; |
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vcpu->arch.fp_state = FP_STATE_HOST_OWNED; |
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vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); |
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if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) |
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vcpu_set_flag(vcpu, HOST_SVE_ENABLED); |
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/* |
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* We don't currently support SME guests but if we leave |
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* things in streaming mode then when the guest starts running |
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* FPSIMD or SVE code it may generate SME traps so as a |
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* special case if we are in streaming mode we force the host |
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* state to be saved now and exit streaming mode so that we |
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* don't have to handle any SME traps for valid guest |
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* operations. Do this for ZA as well for now for simplicity. |
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*/ |
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if (system_supports_sme()) { |
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vcpu_clear_flag(vcpu, HOST_SME_ENABLED); |
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if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN) |
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vcpu_set_flag(vcpu, HOST_SME_ENABLED); |
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if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) { |
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vcpu->arch.fp_state = FP_STATE_FREE; |
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fpsimd_save_and_flush_cpu_state(); |
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} |
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} |
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} |
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/* |
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* Called just before entering the guest once we are no longer preemptable |
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* and interrupts are disabled. If we have managed to run anything using |
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* FP while we were preemptible (such as off the back of an interrupt), |
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* then neither the host nor the guest own the FP hardware (and it was the |
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* responsibility of the code that used FP to save the existing state). |
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*/ |
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void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu) |
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{ |
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if (test_thread_flag(TIF_FOREIGN_FPSTATE)) |
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vcpu->arch.fp_state = FP_STATE_FREE; |
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} |
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/* |
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* Called just after exiting the guest. If the guest FPSIMD state |
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* was loaded, update the host's context tracking data mark the CPU |
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* FPSIMD regs as dirty and belonging to vcpu so that they will be |
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* written back if the kernel clobbers them due to kernel-mode NEON |
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* 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.fp_state == FP_STATE_GUEST_OWNED) { |
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/* |
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* Currently we do not support SME guests so SVCR is |
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* always 0 and we just need a variable to point to. |
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*/ |
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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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NULL, 0, &vcpu->arch.svcr); |
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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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local_irq_save(flags); |
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/* |
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* If we have VHE then the Hyp code will reset CPACR_EL1 to |
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* CPACR_EL1_DEFAULT and we need to reenable SME. |
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*/ |
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if (has_vhe() && system_supports_sme()) { |
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/* Also restore EL0 state seen on entry */ |
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if (vcpu_get_flag(vcpu, HOST_SME_ENABLED)) |
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sysreg_clear_set(CPACR_EL1, 0, |
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CPACR_EL1_SMEN_EL0EN | |
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CPACR_EL1_SMEN_EL1EN); |
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else |
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sysreg_clear_set(CPACR_EL1, |
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CPACR_EL1_SMEN_EL0EN, |
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CPACR_EL1_SMEN_EL1EN); |
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} |
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if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) { |
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if (vcpu_has_sve(vcpu)) { |
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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() && system_supports_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_get_flag(vcpu, 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, 0); |
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local_irq_restore(flags); |
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}
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