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    Subject[PATCH 4.9 09/66] KVM: arm/arm64: Check pagesize when allocating a hugepage at Stage 2
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Punit Agrawal <punit.agrawal@arm.com>

    commit c507babf10ead4d5c8cca704539b170752a8ac84 upstream.

    KVM only supports PMD hugepages at stage 2 but doesn't actually check
    that the provided hugepage memory pagesize is PMD_SIZE before populating
    stage 2 entries.

    In cases where the backing hugepage size is smaller than PMD_SIZE (such
    as when using contiguous hugepages), KVM can end up creating stage 2
    mappings that extend beyond the supplied memory.

    Fix this by checking for the pagesize of userspace vma before creating
    PMD hugepage at stage 2.

    Fixes: 66b3923a1a0f77a ("arm64: hugetlb: add support for PTE contiguous bit")
    Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
    Cc: Marc Zyngier <marc.zyngier@arm.com>
    Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
    Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/arm/kvm/mmu.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/arch/arm/kvm/mmu.c
    +++ b/arch/arm/kvm/mmu.c
    @@ -1284,7 +1284,7 @@ static int user_mem_abort(struct kvm_vcp
    return -EFAULT;
    }

    - if (is_vm_hugetlb_page(vma) && !logging_active) {
    + if (vma_kernel_pagesize(vma) && !logging_active) {
    hugetlb = true;
    gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
    } else {

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