// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/kvm_types.h>
#include <linux/percpu.h>
#include <linux/preempt.h>
#include <asm/msr.h>
#define CREATE_TRACE_POINTS
#include <asm/msr-trace.h>

struct msr __percpu *msrs_alloc(void)
{
        struct msr __percpu *msrs = NULL;

        msrs = alloc_percpu(struct msr);
        if (!msrs) {
                pr_warn("%s: error allocating msrs\n", __func__);
                return NULL;
        }

        return msrs;
}
EXPORT_SYMBOL(msrs_alloc);

void msrs_free(struct msr __percpu *msrs)
{
        free_percpu(msrs);
}
EXPORT_SYMBOL(msrs_free);

/**
 * msr_read - Read an MSR with error handling
 * @msr: MSR to read
 * @m: value to read into
 *
 * It returns read data only on success, otherwise it doesn't change the output
 * argument @m.
 *
 * Return: %0 for success, otherwise an error code
 */
static int msr_read(u32 msr, struct msr *m)
{
        int err;
        u64 val;

        err = rdmsrq_safe(msr, &val);
        if (!err)
                m->q = val;

        return err;
}

/**
 * msr_write - Write an MSR with error handling
 *
 * @msr: MSR to write
 * @m: value to write
 *
 * Return: %0 for success, otherwise an error code
 */
static int msr_write(u32 msr, struct msr *m)
{
        return wrmsrq_safe(msr, m->q);
}

static inline int __flip_bit(u32 msr, u8 bit, bool set)
{
        struct msr m, m1;
        int err = -EINVAL;

        if (bit > 63)
                return err;

        err = msr_read(msr, &m);
        if (err)
                return err;

        m1 = m;
        if (set)
                m1.q |=  BIT_64(bit);
        else
                m1.q &= ~BIT_64(bit);

        if (m1.q == m.q)
                return 0;

        err = msr_write(msr, &m1);
        if (err)
                return err;

        return 1;
}

/**
 * msr_set_bit - Set @bit in a MSR @msr.
 * @msr: MSR to write
 * @bit: bit number to set
 *
 * Return:
 * * < 0: An error was encountered.
 * * = 0: Bit was already set.
 * * > 0: Hardware accepted the MSR write.
 */
int msr_set_bit(u32 msr, u8 bit)
{
        return __flip_bit(msr, bit, true);
}
EXPORT_SYMBOL_FOR_KVM(msr_set_bit);

/**
 * msr_clear_bit - Clear @bit in a MSR @msr.
 * @msr: MSR to write
 * @bit: bit number to clear
 *
 * Return:
 * * < 0: An error was encountered.
 * * = 0: Bit was already cleared.
 * * > 0: Hardware accepted the MSR write.
 */
int msr_clear_bit(u32 msr, u8 bit)
{
        return __flip_bit(msr, bit, false);
}
EXPORT_SYMBOL_FOR_KVM(msr_clear_bit);

#ifdef CONFIG_TRACEPOINTS
void do_trace_write_msr(u32 msr, u64 val, int failed)
{
        trace_write_msr(msr, val, failed);
}
EXPORT_SYMBOL(do_trace_write_msr);
EXPORT_TRACEPOINT_SYMBOL(write_msr);

void do_trace_read_msr(u32 msr, u64 val, int failed)
{
        trace_read_msr(msr, val, failed);
}
EXPORT_SYMBOL(do_trace_read_msr);
EXPORT_TRACEPOINT_SYMBOL(read_msr);

void do_trace_rdpmc(u32 msr, u64 val, int failed)
{
        trace_rdpmc(msr, val, failed);
}
EXPORT_SYMBOL(do_trace_rdpmc);
EXPORT_TRACEPOINT_SYMBOL(rdpmc);

#endif