blob: 6012b08ecb14e7f6464374cf780c9bf271af1cca [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/kvm_host.h>
#include <asm/fpsimd.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/sysreg.h>
void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu)
struct task_struct *p = vcpu->arch.parent_task;
struct user_fpsimd_state *fpsimd;
if (!is_protected_kvm_enabled() || !p)
fpsimd = &p->thread.uw.fpsimd_state;
kvm_unshare_hyp(fpsimd, fpsimd + 1);
* 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 user_fpsimd_state *fpsimd = &current->thread.uw.fpsimd_state;
/* Make sure the host task fpsimd state is visible to hyp: */
ret = kvm_share_hyp(fpsimd, fpsimd + 1);
if (ret)
return ret;
vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
* We need to keep current's task_struct pinned until its data has been
* unshared with the hypervisor to make sure it is not re-used by the
* kernel and donated to someone else while already shared -- see
* kvm_vcpu_unshare_task_fp() for the matching put_task_struct().
if (is_protected_kvm_enabled()) {
vcpu->arch.parent_task = current;
return 0;
* 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.
void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
vcpu->arch.flags &= ~KVM_ARM64_FP_ENABLED;
vcpu->arch.flags |= KVM_ARM64_FP_HOST;
vcpu->arch.flags &= ~KVM_ARM64_HOST_SVE_ENABLED;
if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
* We don't currently support SME guests but if we leave
* things in streaming mode then when the guest starts running
* FPSIMD or SVE code it may generate SME traps so as a
* special case if we are in streaming mode we force the host
* state to be saved now and exit streaming mode so that we
* don't have to handle any SME traps for valid guest
* operations. Do this for ZA as well for now for simplicity.
if (system_supports_sme()) {
vcpu->arch.flags &= ~KVM_ARM64_HOST_SME_ENABLED;
if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
vcpu->arch.flags |= KVM_ARM64_HOST_SME_ENABLED;
if (read_sysreg_s(SYS_SVCR) &
vcpu->arch.flags &= ~KVM_ARM64_FP_HOST;
* Called just before entering the guest once we are no longer
* preemptable. Syncs the host's TIF_FOREIGN_FPSTATE with the KVM
* mirror of the flag used by the hypervisor.
void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu)
if (test_thread_flag(TIF_FOREIGN_FPSTATE))
vcpu->arch.flags |= KVM_ARM64_FP_FOREIGN_FPSTATE;
vcpu->arch.flags &= ~KVM_ARM64_FP_FOREIGN_FPSTATE;
* Called just after exiting the guest. 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) {
* Currently we do not support SME guests so SVCR is
* always 0 and we just need a variable to point to.
NULL, 0, &vcpu->arch.svcr);
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;
* If we have VHE then the Hyp code will reset CPACR_EL1 to
* CPACR_EL1_DEFAULT and we need to reenable SME.
if (has_vhe() && system_supports_sme()) {
/* Also restore EL0 state seen on entry */
if (vcpu->arch.flags & KVM_ARM64_HOST_SME_ENABLED)
sysreg_clear_set(CPACR_EL1, 0,
if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
if (vcpu_has_sve(vcpu)) {
__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
/* Restore the VL that was saved when bound to the CPU */
if (!has_vhe())
sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,
} else if (has_vhe() && system_supports_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);
update_thread_flag(TIF_SVE, 0);