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    Subject[PATCH v2 03/16] KVM: MMU: properly assert spte on rmap walking path
    Only test present bit is not enough since mmio spte is also set this
    bit, use is_shadow_present_pte() instead of it

    Also move the BUG_ONs to the common function to cleanup the code

    Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
    ---
    arch/x86/kvm/mmu.c | 38 ++++++++++++++++++++------------------
    1 files changed, 20 insertions(+), 18 deletions(-)

    diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    index aee13c6..91518b6 100644
    --- a/arch/x86/kvm/mmu.c
    +++ b/arch/x86/kvm/mmu.c
    @@ -993,17 +993,25 @@ struct rmap_iterator {
    */
    static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter)
    {
    + u64 *sptep;
    +
    if (!rmap)
    return NULL;

    if (!(rmap & 1)) {
    iter->desc = NULL;
    - return (u64 *)rmap;
    + sptep = (u64 *)rmap;
    +
    + goto exit;
    }

    iter->desc = (struct pte_list_desc *)(rmap & ~1ul);
    iter->pos = 0;
    - return iter->desc->sptes[iter->pos];
    + sptep = iter->desc->sptes[iter->pos];
    +
    +exit:
    + WARN_ON(sptep && !is_shadow_present_pte(*sptep));
    + return sptep;
    }

    /*
    @@ -1013,14 +1021,14 @@ static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter)
    */
    static u64 *rmap_get_next(struct rmap_iterator *iter)
    {
    + u64 *sptep = NULL;
    +
    if (iter->desc) {
    if (iter->pos < PTE_LIST_EXT - 1) {
    - u64 *sptep;
    -
    ++iter->pos;
    sptep = iter->desc->sptes[iter->pos];
    if (sptep)
    - return sptep;
    + goto exit;
    }

    iter->desc = iter->desc->more;
    @@ -1028,11 +1036,14 @@ static u64 *rmap_get_next(struct rmap_iterator *iter)
    if (iter->desc) {
    iter->pos = 0;
    /* desc->sptes[0] cannot be NULL */
    - return iter->desc->sptes[iter->pos];
    + sptep = iter->desc->sptes[iter->pos];
    + goto exit;
    }
    }

    - return NULL;
    +exit:
    + WARN_ON(sptep && !is_shadow_present_pte(*sptep));
    + return sptep;
    }

    static void drop_spte(struct kvm *kvm, u64 *sptep)
    @@ -1048,7 +1059,6 @@ static int __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level
    int write_protected = 0;

    for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
    - BUG_ON(!(*sptep & PT_PRESENT_MASK));
    rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);

    if (!is_writable_pte(*sptep)) {
    @@ -1123,7 +1133,6 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
    int need_tlb_flush = 0;

    while ((sptep = rmap_get_first(*rmapp, &iter))) {
    - BUG_ON(!(*sptep & PT_PRESENT_MASK));
    rmap_printk("kvm_rmap_unmap_hva: spte %p %llx\n", sptep, *sptep);

    drop_spte(kvm, sptep);
    @@ -1147,7 +1156,6 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
    new_pfn = pte_pfn(*ptep);

    for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
    - BUG_ON(!is_shadow_present_pte(*sptep));
    rmap_printk("kvm_set_pte_rmapp: spte %p %llx\n", sptep, *sptep);

    need_flush = 1;
    @@ -1242,14 +1250,11 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
    return kvm_unmap_rmapp(kvm, rmapp, data);

    for (sptep = rmap_get_first(*rmapp, &iter); sptep;
    - sptep = rmap_get_next(&iter)) {
    - BUG_ON(!(*sptep & PT_PRESENT_MASK));
    -
    + sptep = rmap_get_next(&iter))
    if (*sptep & PT_ACCESSED_MASK) {
    young = 1;
    clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)sptep);
    }
    - }

    return young;
    }
    @@ -1270,14 +1275,11 @@ static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
    goto out;

    for (sptep = rmap_get_first(*rmapp, &iter); sptep;
    - sptep = rmap_get_next(&iter)) {
    - BUG_ON(!(*sptep & PT_PRESENT_MASK));
    -
    + sptep = rmap_get_next(&iter))
    if (*sptep & PT_ACCESSED_MASK) {
    young = 1;
    break;
    }
    - }
    out:
    return young;
    }
    --
    1.7.7.6


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