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kvm: mmu: don't do memslot overflow check 

As Andres pointed out:

| I don't understand the value of this check here. Are we looking for a
| broken memslot? Shouldn't this be a BUG_ON? Is this the place to care
| about these things? npages is capped to KVM_MEM_MAX_NR_PAGES, i.e.
| 2^31. A 64 bit overflow would be caused by a gigantic gfn_start which
| would be trouble in many other ways.

This patch drops the memslot overflow check to make the codes more simple.

Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Message-Id: <1429064694-3072-1-git-send-email-wanpeng.li@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Wanpeng Li 2015-04-15 10:24:54 +08:00 committed by Paolo Bonzini
parent 95fce4fa08
commit 130005231c
1 changed files with 2 additions and 10 deletions
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12
arch/x86/kvm/mmu.c
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@ -4504,19 +4504,12 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
bool flush = false;
unsigned long *rmapp;
unsigned long last_index, index;
gfn_t gfn_start, gfn_end;
spin_lock(&kvm->mmu_lock);
gfn_start = memslot->base_gfn;
gfn_end = memslot->base_gfn + memslot->npages - 1;
if (gfn_start >= gfn_end)
goto out;
rmapp = memslot->arch.rmap[0];
last_index = gfn_to_index(gfn_end, memslot->base_gfn,
PT_PAGE_TABLE_LEVEL);
last_index = gfn_to_index(memslot->base_gfn + memslot->npages - 1,
memslot->base_gfn, PT_PAGE_TABLE_LEVEL);
for (index = 0; index <= last_index; ++index, ++rmapp) {
if (*rmapp)
@ -4534,7 +4527,6 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
if (flush)
kvm_flush_remote_tlbs(kvm);
out:
spin_unlock(&kvm->mmu_lock);
}