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// SPDX-License-Identifier: GPL-2.0
/*
* arch/arm64/kvm/fpsimd.c: Guest/host FPSIMD context coordination helpers
*
* Copyright 2018 Arm Limited
* Author: Dave Martin <Dave.Martin@arm.com>
*/
#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_host.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 = ¤t->thread_info;
struct user_fpsimd_state *fpsimd = ¤t->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);
error:
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)
{
BUG_ON(!current->mm);
vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
KVM_ARM64_HOST_SVE_IN_USE |
KVM_ARM64_HOST_SVE_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)
{
WARN_ON_ONCE(!irqs_disabled());
if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.gp_regs.fp_regs,
vcpu->arch.sve_state,
vcpu->arch.sve_max_vl);
clear_thread_flag(TIF_FOREIGN_FPSTATE);
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);
local_irq_save(flags);
if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
u64 *guest_zcr = &vcpu->arch.ctxt.sys_regs[ZCR_EL1];
/* Clean guest FP state to memory and invalidate cpu view */
fpsimd_save();
fpsimd_flush_cpu_state();
if (guest_has_sve)
*guest_zcr = 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);
else
sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
}
update_thread_flag(TIF_SVE,
vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
local_irq_restore(flags);
}
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