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KVM: do not bias the generation number in kvm_current_mmio_generation

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The next patch will give a meaning (a la seqcount) to the low bit of the
generation number.  Ensure that it matches between kvm->memslots->generation
and kvm_current_mmio_generation().

Cc: stable@vger.kernel.org
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-08-20 14:29:21 +02:00
parent fd2752352b
commit 00f034a12f
2 changed files with 8 additions and 6 deletions
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7
arch/x86/kvm/mmu.c
View File

@ -236,12 +236,7 @@ static unsigned int get_mmio_spte_generation(u64 spte)
static unsigned int kvm_current_mmio_generation(struct kvm *kvm)
{
/*
* Init kvm generation close to MMIO_MAX_GEN to easily test the
* code of handling generation number wrap-around.
*/
return (kvm_memslots(kvm)->generation +
MMIO_MAX_GEN - 150) & MMIO_GEN_MASK;
return kvm_memslots(kvm)->generation & MMIO_GEN_MASK;
}
static void mark_mmio_spte(struct kvm *kvm, u64 *sptep, u64 gfn,

7
virt/kvm/kvm_main.c
View File

@ -477,6 +477,13 @@ static struct kvm *kvm_create_vm(unsigned long type)
kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
if (!kvm->memslots)
goto out_err_no_srcu;
/*
* Init kvm generation close to the maximum to easily test the
* code of handling generation number wrap-around.
*/
kvm->memslots->generation = -150;
kvm_init_memslots_id(kvm);
if (init_srcu_struct(&kvm->srcu))
goto out_err_no_srcu;