#define pr_fmt(fmt)  "Hyper-V: " fmt

#include <linux/log2.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <asm/fpu/api.h>
#include <asm/mshyperv.h>
#include <asm/msr.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>

#define CREATE_TRACE_POINTS
#include <asm/trace/hyperv.h>

/* Each gva in gva_list encodes up to 4096 pages to flush */
#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE)

static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
                                      const struct flush_tlb_info *info);

/*
 * Fills in gva_list starting from offset. Returns the number of items added.
 */
static inline int fill_gva_list(u64 gva_list[], int offset,
                                unsigned long start, unsigned long end)
{
        int gva_n = offset;
        unsigned long cur = start, diff;

        do {
                diff = end > cur ? end - cur : 0;

                gva_list[gva_n] = cur & PAGE_MASK;
                /*
                 * Lower 12 bits encode the number of additional
                 * pages to flush (in addition to the 'cur' page).
                 */
                if (diff >= HV_TLB_FLUSH_UNIT) {
                        gva_list[gva_n] |= ~PAGE_MASK;
                        cur += HV_TLB_FLUSH_UNIT;
                }  else if (diff) {
                        gva_list[gva_n] |= (diff - 1) >> PAGE_SHIFT;
                        cur = end;
                }

                gva_n++;

        } while (cur < end);

        return gva_n - offset;
}

static bool cpu_is_lazy(int cpu)
{
        return per_cpu(cpu_tlbstate_shared.is_lazy, cpu);
}

static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
                                   const struct flush_tlb_info *info)
{
        int cpu, vcpu, gva_n, max_gvas;
        struct hv_tlb_flush *flush;
        u64 status;
        unsigned long flags;
        bool do_lazy = !info->freed_tables;

        trace_hyperv_mmu_flush_tlb_multi(cpus, info);

        if (!hv_hypercall_pg)
                goto do_native;

        local_irq_save(flags);

        flush = *this_cpu_ptr(hyperv_pcpu_input_arg);

        if (unlikely(!flush)) {
                local_irq_restore(flags);
                goto do_native;
        }

        if (info->mm) {
                /*
                 * AddressSpace argument must match the CR3 with PCID bits
                 * stripped out.
                 */
                flush->address_space = virt_to_phys(info->mm->pgd);
                flush->address_space &= CR3_ADDR_MASK;
                flush->flags = 0;
        } else {
                flush->address_space = 0;
                flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES;
        }

        flush->processor_mask = 0;
        if (cpumask_equal(cpus, cpu_present_mask)) {
                flush->flags |= HV_FLUSH_ALL_PROCESSORS;
        } else {
                /*
                 * From the supplied CPU set we need to figure out if we can get
                 * away with cheaper HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}
                 * hypercalls. This is possible when the highest VP number in
                 * the set is < 64. As VP numbers are usually in ascending order
                 * and match Linux CPU ids, here is an optimization: we check
                 * the VP number for the highest bit in the supplied set first
                 * so we can quickly find out if using *_EX hypercalls is a
                 * must. We will also check all VP numbers when walking the
                 * supplied CPU set to remain correct in all cases.
                 */
                cpu = cpumask_last(cpus);

                if (cpu < nr_cpumask_bits && hv_cpu_number_to_vp_number(cpu) >= 64)
                        goto do_ex_hypercall;

                for_each_cpu(cpu, cpus) {
                        if (do_lazy && cpu_is_lazy(cpu))
                                continue;
                        vcpu = hv_cpu_number_to_vp_number(cpu);
                        if (vcpu == VP_INVAL) {
                                local_irq_restore(flags);
                                goto do_native;
                        }

                        if (vcpu >= 64)
                                goto do_ex_hypercall;

                        __set_bit(vcpu, (unsigned long *)
                                  &flush->processor_mask);
                }

                /* nothing to flush if 'processor_mask' ends up being empty */
                if (!flush->processor_mask) {
                        local_irq_restore(flags);
                        return;
                }
        }

        /*
         * We can flush not more than max_gvas with one hypercall. Flush the
         * whole address space if we were asked to do more.
         */
        max_gvas = (PAGE_SIZE - sizeof(*flush)) / sizeof(flush->gva_list[0]);

        if (info->end == TLB_FLUSH_ALL) {
                flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY;
                status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
                                         flush, NULL);
        } else if (info->end &&
                   ((info->end - info->start)/HV_TLB_FLUSH_UNIT) > max_gvas) {
                status = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE,
                                         flush, NULL);
        } else {
                gva_n = fill_gva_list(flush->gva_list, 0,
                                      info->start, info->end);
                status = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST,
                                             gva_n, 0, flush, NULL);
        }
        goto check_status;

do_ex_hypercall:
        status = hyperv_flush_tlb_others_ex(cpus, info);

check_status:
        local_irq_restore(flags);

        if (hv_result_success(status))
                return;
do_native:
        native_flush_tlb_multi(cpus, info);
}

static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
                                      const struct flush_tlb_info *info)
{
        int nr_bank = 0, max_gvas, gva_n;
        struct hv_tlb_flush_ex *flush;
        u64 status;

        if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
                return HV_STATUS_INVALID_PARAMETER;

        flush = *this_cpu_ptr(hyperv_pcpu_input_arg);

        if (info->mm) {
                /*
                 * AddressSpace argument must match the CR3 with PCID bits
                 * stripped out.
                 */
                flush->address_space = virt_to_phys(info->mm->pgd);
                flush->address_space &= CR3_ADDR_MASK;
                flush->flags = 0;
        } else {
                flush->address_space = 0;
                flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES;
        }

        flush->hv_vp_set.valid_bank_mask = 0;

        flush->hv_vp_set.format = HV_GENERIC_SET_SPARSE_4K;
        nr_bank = cpumask_to_vpset_skip(&flush->hv_vp_set, cpus,
                        info->freed_tables ? NULL : cpu_is_lazy);
        if (nr_bank < 0)
                return HV_STATUS_INVALID_PARAMETER;

        /*
         * We can flush not more than max_gvas with one hypercall. Flush the
         * whole address space if we were asked to do more.
         *
         * For these hypercalls, Hyper-V treats the valid_bank_mask field
         * of flush->hv_vp_set as part of the fixed size input header.
         * So the variable input header size is equal to nr_bank.
         */
        max_gvas =
                (PAGE_SIZE - sizeof(*flush) - nr_bank *
                 sizeof(flush->hv_vp_set.bank_contents[0])) /
                sizeof(flush->gva_list[0]);

        if (info->end == TLB_FLUSH_ALL) {
                flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY;
                status = hv_do_rep_hypercall(
                        HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX,
                        0, nr_bank, flush, NULL);
        } else if (info->end &&
                   ((info->end - info->start)/HV_TLB_FLUSH_UNIT) > max_gvas) {
                status = hv_do_rep_hypercall(
                        HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX,
                        0, nr_bank, flush, NULL);
        } else {
                gva_n = fill_gva_list(flush->gva_list, nr_bank,
                                      info->start, info->end);
                status = hv_do_rep_hypercall(
                        HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX,
                        gva_n, nr_bank, flush, NULL);
        }

        return status;
}

void hyperv_setup_mmu_ops(void)
{
        if (!(ms_hyperv.hints & HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED))
                return;

        pr_info("Using hypercall for remote TLB flush\n");
        pv_ops.mmu.flush_tlb_multi = hyperv_flush_tlb_multi;
}