blob: 3e081d556e81092c931c4981ffe6d22bc03e5386 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
* arch/arm64/kvm/fpsimd.c: Guest/host FPSIMD context coordination helpers
* Copyright 2018 Arm Limited
* Author: Dave Martin <>
#include <linux/irqflags.h>
#include <linux/sched.h>
#include <linux/thread_info.h>
#include <linux/kvm_host.h>
#include <asm/fpsimd.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmu.h>
#include <asm/sysreg.h>
* Called on entry to KVM_RUN unless this vcpu previously ran at least
* once and the most recent prior KVM_RUN for this vcpu was called from
* the same task as current (highly likely).
* This is guaranteed to execute before kvm_arch_vcpu_load_fp(vcpu),
* such that on entering hyp the relevant parts of current are already
* mapped.
int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
int ret;
struct thread_info *ti = &current->thread_info;
struct user_fpsimd_state *fpsimd = &current->thread.uw.fpsimd_state;
* Make sure the host task thread flags and fpsimd state are
* visible to hyp:
ret = create_hyp_mappings(ti, ti + 1, PAGE_HYP);
if (ret)
goto error;
ret = create_hyp_mappings(fpsimd, fpsimd + 1, PAGE_HYP);
if (ret)
goto error;
vcpu->arch.host_thread_info = kern_hyp_va(ti);
vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
return ret;
* Prepare vcpu for saving the host's FPSIMD state and loading the guest's.
* The actual loading is done by the FPSIMD access trap taken to hyp.
* Here, we just set the correct metadata to indicate that the FPSIMD
* state in the cpu regs (if any) belongs to current on the host.
* TIF_SVE is backed up here, since it may get clobbered with guest state.
* This flag is restored by kvm_arch_vcpu_put_fp(vcpu).
void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
vcpu->arch.flags |= KVM_ARM64_FP_HOST;
if (test_thread_flag(TIF_SVE))
vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE;
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
* If the guest FPSIMD state was loaded, update the host's context
* tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu
* so that they will be written back if the kernel clobbers them due to
* kernel-mode NEON before re-entry into the guest.
void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
update_thread_flag(TIF_SVE, vcpu_has_sve(vcpu));
* Write back the vcpu FPSIMD regs if they are dirty, and invalidate the
* cpu FPSIMD regs so that they can't be spuriously reused if this vcpu
* disappears and another task or vcpu appears that recycles the same
* struct fpsimd_state.
void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
unsigned long flags;
bool host_has_sve = system_supports_sve();
bool guest_has_sve = vcpu_has_sve(vcpu);
if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
if (guest_has_sve)
__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_s(SYS_ZCR_EL12);
} else if (host_has_sve) {
* The FPSIMD/SVE state in the CPU has not been touched, and we
* have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
* reset to CPACR_EL1_DEFAULT by the Hyp code, disabling SVE
* for EL0. To avoid spurious traps, restore the trap state
* seen by kvm_arch_vcpu_load_fp():
if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED)
sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);