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SubjectRe: [PATCH 1/4] KVM: MMU: Split the main body of rmap_write_protect() off from others
Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> wrote:

> -int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,
> - struct kvm_memory_slot *slot)
> +static int __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)
> {
> - unsigned long *rmapp;
> - u64 *spte;
> - int i, write_protected = 0;
> + u64 *spte = NULL;
> + int write_protected = 0;
>
> - rmapp = __gfn_to_rmap(gfn, PT_PAGE_TABLE_LEVEL, slot);
> - spte = rmap_next(rmapp, NULL);
> - while (spte) {
> + while ((spte = rmap_next(rmapp, spte))) {
> BUG_ON(!(*spte & PT_PRESENT_MASK));
> rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
> - if (is_writable_pte(*spte)) {
> +
> + if (!is_writable_pte(*spte))
> + continue;
> +
> + if (level == PT_PAGE_TABLE_LEVEL) {
> mmu_spte_update(spte, *spte & ~PT_WRITABLE_MASK);
> - write_protected = 1;
> + } else {
> + BUG_ON(!is_large_pte(*spte));
> + drop_spte(kvm, spte);
> + --kvm->stat.lpages;
> + spte = NULL;
> }
> - spte = rmap_next(rmapp, spte);
> +
> + write_protected = 1;
> }

Something may change here: when level > PT_PAGE_TABLE_LEVEL, this loop
does not handle lower level mappings after dropping large-ptes.

This may be incorrect.

Takuya


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