From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH v02 6/7] arm: introduce
 do_translate_pagetable hypercall
Date: Fri, 04 Jul 2014 15:35:05 +0100
Message-ID: <53B6BB99.7060107@linaro.org>
References: <1403780826-22123-1-git-send-email-andrii.tseglytskyi@globallogic.com>
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To: Andrii Tseglytskyi <andrii.tseglytskyi@globallogic.com>, xen-devel@lists.xen.org, Ian Campbell <Ian.Campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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Hi Andrii,

On 26/06/14 12:07, Andrii Tseglytskyi wrote:
> +long do_translate_pagetable(int cmd, XEN_GUEST_HANDLE_PARAM(xen_pagetable_addr_t) pgt_addr)
> +{
> +    struct xen_pagetable_addr pgt;
> +    struct mmu_info *mmu = NULL;
> +
> +    if ( copy_from_guest(&pgt, pgt_addr, 1) )
> +        return -EFAULT;
> +
> +    mmu = mmu_lookup(pgt.reg);
> +    if ( !mmu )
> +    {
> +        pr_mmu("can't get mmu for addr 0x%08x", pgt.reg);
> +        return -EINVAL;
> +    }
> +
> +    pgt.maddr = mmu_translate_pagetable(mmu, pgt.paddr);
> +
> +    return copy_to_guest(pgt_addr, &pgt, 1);
> +}
> +

AFAIU, nothing prevents a malicious guest to call this hypercall and 
screw the pagetable of the MMU.

Regards,

-- 
Julien Grall