lkml.org 
[lkml]   [2012]   [Mar]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH 1/4] KVM: MMU: Split the main body of rmap_write_protect() off from others
    We will use this in the following patch to implement another function
    which needs to write protect pages using the rmap information.

    Note that there is a small change in debug printing for large pages:
    we do not differentiate them from others to avoid duplicating code.

    Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
    ---
    arch/x86/kvm/mmu.c | 53 ++++++++++++++++++++++++++-------------------------
    1 files changed, 27 insertions(+), 26 deletions(-)

    diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    index ff053ca..67857bd 100644
    --- a/arch/x86/kvm/mmu.c
    +++ b/arch/x86/kvm/mmu.c
    @@ -1010,42 +1010,43 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
    rmap_remove(kvm, sptep);
    }

    -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;
    }

    - /* check for huge page mappings */
    - for (i = PT_DIRECTORY_LEVEL;
    + return write_protected;
    +}
    +
    +int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,
    + struct kvm_memory_slot *slot)
    +{
    + unsigned long *rmapp;
    + int i, write_protected = 0;
    +
    + for (i = PT_PAGE_TABLE_LEVEL;
    i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
    rmapp = __gfn_to_rmap(gfn, i, slot);
    - spte = rmap_next(rmapp, NULL);
    - while (spte) {
    - BUG_ON(!(*spte & PT_PRESENT_MASK));
    - BUG_ON(!is_large_pte(*spte));
    - pgprintk("rmap_write_protect(large): spte %p %llx %lld\n", spte, *spte, gfn);
    - if (is_writable_pte(*spte)) {
    - drop_spte(kvm, spte);
    - --kvm->stat.lpages;
    - spte = NULL;
    - write_protected = 1;
    - }
    - spte = rmap_next(rmapp, spte);
    - }
    + write_protected |= __rmap_write_protect(kvm, rmapp, i);
    }

    return write_protected;
    --
    1.7.5.4


    \
     
     \ /
      Last update: 2012-03-01 11:27    [W:0.022 / U:30.032 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site