setup.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Google LLC
 * Author: Quentin Perret <qperret@google.com>
 */
 
#include <linux/kvm_host.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_pgtable.h>
#include <asm/kvm_pkvm.h>
 
#include <nvhe/early_alloc.h>
#include <nvhe/ffa.h>
#include <nvhe/fixed_config.h>
#include <nvhe/gfp.h>
#include <nvhe/memory.h>
#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
#include <nvhe/pkvm.h>
#include <nvhe/trap_handler.h>
 
unsigned long hyp_nr_cpus;
 
#define hyp_percpu_size ((unsigned long)__per_cpu_end - \
             (unsigned long)__per_cpu_start)
 
static void *vmemmap_base;
static void *vm_table_base;
static void *hyp_pgt_base;
static void *host_s2_pgt_base;
static void *ffa_proxy_pages;
static struct kvm_pgtable_mm_ops pkvm_pgtable_mm_ops;
static struct hyp_pool hpool;
 
static int divide_memory_pool(void *virt, unsigned long size)
{
    unsigned long nr_pages;
 
    hyp_early_alloc_init(virt, size);
 
    nr_pages = hyp_vmemmap_pages(sizeof(struct hyp_page));
    vmemmap_base = hyp_early_alloc_contig(nr_pages);
    if (!vmemmap_base)
        return -ENOMEM;
 
    nr_pages = hyp_vm_table_pages();
    vm_table_base = hyp_early_alloc_contig(nr_pages);
    if (!vm_table_base)
        return -ENOMEM;
 
    nr_pages = hyp_s1_pgtable_pages();
    hyp_pgt_base = hyp_early_alloc_contig(nr_pages);
    if (!hyp_pgt_base)
        return -ENOMEM;
 
    nr_pages = host_s2_pgtable_pages();
    host_s2_pgt_base = hyp_early_alloc_contig(nr_pages);
    if (!host_s2_pgt_base)
        return -ENOMEM;
 
    nr_pages = hyp_ffa_proxy_pages();
    ffa_proxy_pages = hyp_early_alloc_contig(nr_pages);
    if (!ffa_proxy_pages)
        return -ENOMEM;
 
    return 0;
}
 
static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
                 unsigned long *per_cpu_base,
                 u32 hyp_va_bits)
{
    void *start, *end, *virt = hyp_phys_to_virt(phys);
    unsigned long pgt_size = hyp_s1_pgtable_pages() << PAGE_SHIFT;
    enum kvm_pgtable_prot prot;
    int ret, i;
 
    /* Recreate the hyp page-table using the early page allocator */
    hyp_early_alloc_init(hyp_pgt_base, pgt_size);
    ret = kvm_pgtable_hyp_init(&pkvm_pgtable, hyp_va_bits,
                   &hyp_early_alloc_mm_ops);
    if (ret)
        return ret;
 
    ret = hyp_create_idmap(hyp_va_bits);
    if (ret)
        return ret;
 
    ret = hyp_map_vectors();
    if (ret)
        return ret;
 
    ret = hyp_back_vmemmap(hyp_virt_to_phys(vmemmap_base));
    if (ret)
        return ret;
 
    ret = pkvm_create_mappings(__hyp_text_start, __hyp_text_end, PAGE_HYP_EXEC);
    if (ret)
        return ret;
 
    ret = pkvm_create_mappings(__hyp_rodata_start, __hyp_rodata_end, PAGE_HYP_RO);
    if (ret)
        return ret;
 
    ret = pkvm_create_mappings(__hyp_bss_start, __hyp_bss_end, PAGE_HYP);
    if (ret)
        return ret;
 
    ret = pkvm_create_mappings(virt, virt + size, PAGE_HYP);
    if (ret)
        return ret;
 
    for (i = 0; i < hyp_nr_cpus; i++) {
        struct kvm_nvhe_init_params *params = per_cpu_ptr(&kvm_init_params, i);
 
        start = (void *)kern_hyp_va(per_cpu_base[i]);
        end = start + PAGE_ALIGN(hyp_percpu_size);
        ret = pkvm_create_mappings(start, end, PAGE_HYP);
        if (ret)
            return ret;
 
        ret = pkvm_create_stack(params->stack_pa, &params->stack_hyp_va);
        if (ret)
            return ret;
    }
 
    /*
     * Map the host sections RO in the hypervisor, but transfer the
     * ownership from the host to the hypervisor itself to make sure they
     * can't be donated or shared with another entity.
     *
     * The ownership transition requires matching changes in the host
     * stage-2. This will be done later (see finalize_host_mappings()) once
     * the hyp_vmemmap is addressable.
     */
    prot = pkvm_mkstate(PAGE_HYP_RO, PKVM_PAGE_SHARED_OWNED);
    ret = pkvm_create_mappings(&kvm_vgic_global_state,
                   &kvm_vgic_global_state + 1, prot);
    if (ret)
        return ret;
 
    return 0;
}
 
static void update_nvhe_init_params(void)
{
    struct kvm_nvhe_init_params *params;
    unsigned long i;
 
    for (i = 0; i < hyp_nr_cpus; i++) {
        params = per_cpu_ptr(&kvm_init_params, i);
        params->pgd_pa = __hyp_pa(pkvm_pgtable.pgd);
        dcache_clean_inval_poc((unsigned long)params,
                    (unsigned long)params + sizeof(*params));
    }
}
 
static void *hyp_zalloc_hyp_page(void *arg)
{
    return hyp_alloc_pages(&hpool, 0);
}
 
static void hpool_get_page(void *addr)
{
    hyp_get_page(&hpool, addr);
}
 
static void hpool_put_page(void *addr)
{
    hyp_put_page(&hpool, addr);
}
 
static int fix_host_ownership_walker(const struct kvm_pgtable_visit_ctx *ctx,
                     enum kvm_pgtable_walk_flags visit)
{
    enum kvm_pgtable_prot prot;
    enum pkvm_page_state state;
    phys_addr_t phys;
 
    if (!kvm_pte_valid(ctx->old))
        return 0;
 
    if (ctx->level != KVM_PGTABLE_LAST_LEVEL)
        return -EINVAL;
 
    phys = kvm_pte_to_phys(ctx->old);
    if (!addr_is_memory(phys))
        return -EINVAL;
 
    /*
     * Adjust the host stage-2 mappings to match the ownership attributes
     * configured in the hypervisor stage-1.
     */
    state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(ctx->old));
    switch (state) {
    case PKVM_PAGE_OWNED:
        return host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_HYP);
    case PKVM_PAGE_SHARED_OWNED:
        prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_BORROWED);
        break;
    case PKVM_PAGE_SHARED_BORROWED:
        prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_OWNED);
        break;
    default:
        return -EINVAL;
    }
 
    return host_stage2_idmap_locked(phys, PAGE_SIZE, prot);
}
 
static int fix_hyp_pgtable_refcnt_walker(const struct kvm_pgtable_visit_ctx *ctx,
                     enum kvm_pgtable_walk_flags visit)
{
    /*
     * Fix-up the refcount for the page-table pages as the early allocator
     * was unable to access the hyp_vmemmap and so the buddy allocator has
     * initialised the refcount to '1'.
     */
    if (kvm_pte_valid(ctx->old))
        ctx->mm_ops->get_page(ctx->ptep);
 
    return 0;
}
 
static int fix_host_ownership(void)
{
    struct kvm_pgtable_walker walker = {
        .cb = fix_host_ownership_walker,
        .flags  = KVM_PGTABLE_WALK_LEAF,
    };
    int i, ret;
 
    for (i = 0; i < hyp_memblock_nr; i++) {
        struct memblock_region *reg = &hyp_memory[i];
        u64 start = (u64)hyp_phys_to_virt(reg->base);
 
        ret = kvm_pgtable_walk(&pkvm_pgtable, start, reg->size, &walker);
        if (ret)
            return ret;
    }
 
    return 0;
}
 
static int fix_hyp_pgtable_refcnt(void)
{
    struct kvm_pgtable_walker walker = {
        .cb = fix_hyp_pgtable_refcnt_walker,
        .flags  = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
        .arg    = pkvm_pgtable.mm_ops,
    };
 
    return kvm_pgtable_walk(&pkvm_pgtable, 0, BIT(pkvm_pgtable.ia_bits),
                &walker);
}
 
void __noreturn __pkvm_init_finalise(void)
{
    struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data);
    struct kvm_cpu_context *host_ctxt = &host_data->host_ctxt;
    unsigned long nr_pages, reserved_pages, pfn;
    int ret;
 
    /* Now that the vmemmap is backed, install the full-fledged allocator */
    pfn = hyp_virt_to_pfn(hyp_pgt_base);
    nr_pages = hyp_s1_pgtable_pages();
    reserved_pages = hyp_early_alloc_nr_used_pages();
    ret = hyp_pool_init(&hpool, pfn, nr_pages, reserved_pages);
    if (ret)
        goto out;
 
    ret = kvm_host_prepare_stage2(host_s2_pgt_base);
    if (ret)
        goto out;
 
    pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
        .zalloc_page = hyp_zalloc_hyp_page,
        .phys_to_virt = hyp_phys_to_virt,
        .virt_to_phys = hyp_virt_to_phys,
        .get_page = hpool_get_page,
        .put_page = hpool_put_page,
        .page_count = hyp_page_count,
    };
    pkvm_pgtable.mm_ops = &pkvm_pgtable_mm_ops;
 
    ret = fix_host_ownership();
    if (ret)
        goto out;
 
    ret = fix_hyp_pgtable_refcnt();
    if (ret)
        goto out;
 
    ret = hyp_create_pcpu_fixmap();
    if (ret)
        goto out;
 
    ret = hyp_ffa_init(ffa_proxy_pages);
    if (ret)
        goto out;
 
    pkvm_hyp_vm_table_init(vm_table_base);
out:
    /*
     * We tail-called to here from handle___pkvm_init() and will not return,
     * so make sure to propagate the return value to the host.
     */
    cpu_reg(host_ctxt, 1) = ret;
 
    __host_enter(host_ctxt);
}
 
int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
        unsigned long *per_cpu_base, u32 hyp_va_bits)
{
    struct kvm_nvhe_init_params *params;
    void *virt = hyp_phys_to_virt(phys);
    void (*fn)(phys_addr_t params_pa, void *finalize_fn_va);
    int ret;
 
    BUG_ON(kvm_check_pvm_sysreg_table());
 
    if (!PAGE_ALIGNED(phys) || !PAGE_ALIGNED(size))
        return -EINVAL;
 
    hyp_spin_lock_init(&pkvm_pgd_lock);
    hyp_nr_cpus = nr_cpus;
 
    ret = divide_memory_pool(virt, size);
    if (ret)
        return ret;
 
    ret = recreate_hyp_mappings(phys, size, per_cpu_base, hyp_va_bits);
    if (ret)
        return ret;
 
    update_nvhe_init_params();
 
    /* Jump in the idmap page to switch to the new page-tables */
    params = this_cpu_ptr(&kvm_init_params);
    fn = (typeof(fn))__hyp_pa(__pkvm_init_switch_pgd);
    fn(__hyp_pa(params), __pkvm_init_finalise);
 
    unreachable();
}