// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2015 - ARM Ltd
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 */

#include <hyp/debug-sr.h>

#include <linux/compiler.h>
#include <linux/kvm_host.h>

#include <asm/debug-monitors.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>

static void __debug_save_spe(void)
{
        u64 *pmscr_el1, *pmblimitr_el1;

        pmscr_el1 = host_data_ptr(host_debug_state.pmscr_el1);
        pmblimitr_el1 = host_data_ptr(host_debug_state.pmblimitr_el1);

        /*
         * At this point, we know that this CPU implements
         * SPE and is available to the host.
         * Check if the host is actually using it ?
         */
        *pmblimitr_el1 = read_sysreg_s(SYS_PMBLIMITR_EL1);
        if (!(*pmblimitr_el1 & BIT(PMBLIMITR_EL1_E_SHIFT)))
                return;

        /* Yes; save the control register and disable data generation */
        *pmscr_el1 = read_sysreg_el1(SYS_PMSCR);
        write_sysreg_el1(0, SYS_PMSCR);
        isb();

        /* Now drain all buffered data to memory */
        psb_csync();
        dsb(nsh);

        /* And disable the profiling buffer */
        write_sysreg_s(0, SYS_PMBLIMITR_EL1);
        isb();
}

static void __debug_restore_spe(void)
{
        u64 pmblimitr_el1 = *host_data_ptr(host_debug_state.pmblimitr_el1);

        if (!(pmblimitr_el1 & BIT(PMBLIMITR_EL1_E_SHIFT)))
                return;

        /* The host page table is installed, but not yet synchronised */
        isb();

        /* Re-enable the profiling buffer. */
        write_sysreg_s(pmblimitr_el1, SYS_PMBLIMITR_EL1);
        isb();

        /* Re-enable data generation */
        write_sysreg_el1(*host_data_ptr(host_debug_state.pmscr_el1), SYS_PMSCR);
}

static void __trace_do_switch(u64 *saved_trfcr, u64 new_trfcr)
{
        *saved_trfcr = read_sysreg_el1(SYS_TRFCR);
        write_sysreg_el1(new_trfcr, SYS_TRFCR);
}

static void __trace_drain_and_disable(void)
{
        u64 *trblimitr_el1 = host_data_ptr(host_debug_state.trblimitr_el1);
        bool needs_drain = is_protected_kvm_enabled() ?
                           host_data_test_flag(HAS_TRBE) :
                           host_data_test_flag(TRBE_ENABLED);

        if (!needs_drain) {
                *trblimitr_el1 = 0;
                return;
        }

        *trblimitr_el1 = read_sysreg_s(SYS_TRBLIMITR_EL1);
        if (*trblimitr_el1 & TRBLIMITR_EL1_E) {
                /*
                 * The host has enabled the Trace Buffer Unit so we have
                 * to beat the CPU with a stick until it stops accessing
                 * memory.
                 */

                /* First, ensure that our prior write to TRFCR has stuck. */
                isb();

                /* Now synchronise with the trace and drain the buffer. */
                tsb_csync();
                dsb(nsh);

                /*
                 * With no more trace being generated, we can disable the
                 * Trace Buffer Unit.
                 */
                write_sysreg_s(0, SYS_TRBLIMITR_EL1);
                if (cpus_have_final_cap(ARM64_WORKAROUND_2064142)) {
                        /*
                         * Some CPUs are so good, we have to drain 'em
                         * twice.
                         */
                        tsb_csync();
                        dsb(nsh);
                }

                /*
                 * Ensure that the Trace Buffer Unit is disabled before
                 * we start mucking with the stage-2 and trap
                 * configuration.
                 */
                isb();
        }
}

static bool __trace_needs_switch(void)
{
        return host_data_test_flag(TRBE_ENABLED) ||
               host_data_test_flag(EL1_TRACING_CONFIGURED);
}

static void __trace_switch_to_guest(void)
{
        /* Unsupported with TRBE so disable */
        if (host_data_test_flag(TRBE_ENABLED))
                *host_data_ptr(trfcr_while_in_guest) = 0;

        __trace_do_switch(host_data_ptr(host_debug_state.trfcr_el1),
                          *host_data_ptr(trfcr_while_in_guest));
        __trace_drain_and_disable();
}

static void __trace_switch_to_host(void)
{
        u64 trblimitr_el1 = *host_data_ptr(host_debug_state.trblimitr_el1);

        if (trblimitr_el1 & TRBLIMITR_EL1_E) {
                /* Re-enable the Trace Buffer Unit for the host. */
                write_sysreg_s(trblimitr_el1, SYS_TRBLIMITR_EL1);
                isb();
                if (cpus_have_final_cap(ARM64_WORKAROUND_2038923)) {
                        /*
                         * Make sure the unit is re-enabled before we
                         * poke TRFCR.
                         */
                        isb();
                }
        }

        __trace_do_switch(host_data_ptr(trfcr_while_in_guest),
                          *host_data_ptr(host_debug_state.trfcr_el1));
}

static void __debug_save_brbe(void)
{
        u64 *brbcr_el1 = host_data_ptr(host_debug_state.brbcr_el1);

        *brbcr_el1 = 0;

        /* Check if the BRBE is enabled */
        if (!(read_sysreg_el1(SYS_BRBCR) & (BRBCR_ELx_E0BRE | BRBCR_ELx_ExBRE)))
                return;

        /*
         * Prohibit branch record generation while we are in guest.
         * Since access to BRBCR_EL1 is trapped, the guest can't
         * modify the filtering set by the host.
         */
        *brbcr_el1 = read_sysreg_el1(SYS_BRBCR);
        write_sysreg_el1(0, SYS_BRBCR);
}

static void __debug_restore_brbe(void)
{
        u64 brbcr_el1 = *host_data_ptr(host_debug_state.brbcr_el1);

        if (!brbcr_el1)
                return;

        /* Restore BRBE controls */
        write_sysreg_el1(brbcr_el1, SYS_BRBCR);
}

void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
{
        /* Disable and flush SPE data generation */
        if (host_data_test_flag(HAS_SPE))
                __debug_save_spe();

        /* Disable BRBE branch records */
        if (host_data_test_flag(HAS_BRBE))
                __debug_save_brbe();

        if (__trace_needs_switch())
                __trace_switch_to_guest();
}

void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
{
        __debug_switch_to_guest_common(vcpu);
}

void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
{
        if (host_data_test_flag(HAS_SPE))
                __debug_restore_spe();
        if (host_data_test_flag(HAS_BRBE))
                __debug_restore_brbe();
        if (__trace_needs_switch())
                __trace_switch_to_host();
}

void __debug_switch_to_host(struct kvm_vcpu *vcpu)
{
        __debug_switch_to_host_common(vcpu);
}