sysreg-sr.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012-2015 - ARM Ltd
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 */
 
#include <hyp/sysreg-sr.h>
 
#include <linux/compiler.h>
#include <linux/kvm_host.h>
 
#include <asm/kprobes.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_nested.h>
 
/*
 * VHE: Host and guest must save mdscr_el1 and sp_el0 (and the PC and
 * pstate, which are handled as part of the el2 return state) on every
 * switch (sp_el0 is being dealt with in the assembly code).
 * tpidr_el0 and tpidrro_el0 only need to be switched when going
 * to host userspace or a different VCPU.  EL1 registers only need to be
 * switched when potentially going to run a different VCPU.  The latter two
 * classes are handled as part of kvm_arch_vcpu_load and kvm_arch_vcpu_put.
 */
 
void sysreg_save_host_state_vhe(struct kvm_cpu_context *ctxt)
{
    __sysreg_save_common_state(ctxt);
}
NOKPROBE_SYMBOL(sysreg_save_host_state_vhe);
 
void sysreg_save_guest_state_vhe(struct kvm_cpu_context *ctxt)
{
    __sysreg_save_common_state(ctxt);
    __sysreg_save_el2_return_state(ctxt);
}
NOKPROBE_SYMBOL(sysreg_save_guest_state_vhe);
 
void sysreg_restore_host_state_vhe(struct kvm_cpu_context *ctxt)
{
    __sysreg_restore_common_state(ctxt);
}
NOKPROBE_SYMBOL(sysreg_restore_host_state_vhe);
 
void sysreg_restore_guest_state_vhe(struct kvm_cpu_context *ctxt)
{
    __sysreg_restore_common_state(ctxt);
    __sysreg_restore_el2_return_state(ctxt);
}
NOKPROBE_SYMBOL(sysreg_restore_guest_state_vhe);
 
/**
 * __vcpu_load_switch_sysregs - Load guest system registers to the physical CPU
 *
 * @vcpu: The VCPU pointer
 *
 * Load system registers that do not affect the host's execution, for
 * example EL1 system registers on a VHE system where the host kernel
 * runs at EL2.  This function is called from KVM's vcpu_load() function
 * and loading system register state early avoids having to load them on
 * every entry to the VM.
 */
void __vcpu_load_switch_sysregs(struct kvm_vcpu *vcpu)
{
    struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
    struct kvm_cpu_context *host_ctxt;
 
    host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
    __sysreg_save_user_state(host_ctxt);
 
    /*
     * When running a normal EL1 guest, we only load a new vcpu
     * after a context switch, which imvolves a DSB, so all
     * speculative EL1&0 walks will have already completed.
     * If running NV, the vcpu may transition between vEL1 and
     * vEL2 without a context switch, so make sure we complete
     * those walks before loading a new context.
     */
    if (vcpu_has_nv(vcpu))
        dsb(nsh);
 
    /*
     * Load guest EL1 and user state
     *
     * We must restore the 32-bit state before the sysregs, thanks
     * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
     */
    __sysreg32_restore_state(vcpu);
    __sysreg_restore_user_state(guest_ctxt);
    __sysreg_restore_el1_state(guest_ctxt);
 
    vcpu_set_flag(vcpu, SYSREGS_ON_CPU);
}
 
/**
 * __vcpu_put_switch_syregs - Restore host system registers to the physical CPU
 *
 * @vcpu: The VCPU pointer
 *
 * Save guest system registers that do not affect the host's execution, for
 * example EL1 system registers on a VHE system where the host kernel
 * runs at EL2.  This function is called from KVM's vcpu_put() function
 * and deferring saving system register state until we're no longer running the
 * VCPU avoids having to save them on every exit from the VM.
 */
void __vcpu_put_switch_sysregs(struct kvm_vcpu *vcpu)
{
    struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
    struct kvm_cpu_context *host_ctxt;
 
    host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 
    __sysreg_save_el1_state(guest_ctxt);
    __sysreg_save_user_state(guest_ctxt);
    __sysreg32_save_state(vcpu);
 
    /* Restore host user state */
    __sysreg_restore_user_state(host_ctxt);
 
    vcpu_clear_flag(vcpu, SYSREGS_ON_CPU);
}