[Xen-devel] Address check restriction

[Stefan Berger <stefanb@xxxxxxxxxx>]

Keir,

   I'd like to restrict the address check in the code snipped below so
that addresses in the range 0xFED4 0000 to 0xFED4 5000 do not end up in
the domain_crash() function. I have a virtual device (qemu device model)
that uses addresses in this range. Can I just open up that window with a
check like this or can the window even be further open onto higher
addresses?

    if ( !hvm_apic_support(d) && 
         (((gpa >= 0xFEC00000) && (gpa < FED40000)) ||
           (gpa >= 0xFED45000)  ))


The device is a TPM TIS interface. Specs at:

https://www.trustedcomputinggroup.org/groups/pc_client/TCG_PCClientTPMSpecification_1-20_1-00_FINAL.pdf

Page 27 shows the address range.


from xen/arch/x86/mm/shadow/multi.c:

 mmio:
    perfc_incrc(shadow_fault_mmio);
    if ( !hvm_apic_support(d) && (gpa >= 0xFEC00000) )
    {
        /* Need to deal with these disabled-APIC accesses, as
         * handle_mmio() apparently does not currently do that. */
        /* TJD: What about it, then?   For now, I'm turning this BUG()
         * into a domain_crash() since we don't want to kill Xen. */
        SHADOW_ERROR("disabled-APIC access: not supported\n.");
        domain_crash(d);
    }



  Stefan



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