• Mukesh Rathor's avatar
    xen/pvh: Support ParaVirtualized Hardware extensions (v3). · 4e903a20
    Mukesh Rathor authored
    PVH allows PV linux guest to utilize hardware extended capabilities,
    such as running MMU updates in a HVM container.
    
    The Xen side defines PVH as (from docs/misc/pvh-readme.txt,
    with modifications):
    
    "* the guest uses auto translate:
     - p2m is managed by Xen
     - pagetables are owned by the guest
     - mmu_update hypercall not available
    * it uses event callback and not vlapic emulation,
    * IDT is native, so set_trap_table hcall is also N/A for a PVH guest.
    
    For a full list of hcalls supported for PVH, see pvh_hypercall64_table
    in arch/x86/hvm/hvm.c in xen.  From the ABI prespective, it's mostly a
    PV guest with auto translate, although it does use hvm_op for setting
    callback vector."
    
    Use .ascii and .asciz to define xen feature string. Note, the PVH
    string must be in a single line (not multiple lines with \) to keep the
    assembler from putting null char after each string before \.
    This patch allows it to be configured and enabled.
    
    We also use introduce the 'XEN_ELFNOTE_SUPPORTED_FEATURES' ELF note to
    tell the hypervisor that 'hvm_callback_vector' is what the kernel
    needs. We can not put it in 'XEN_ELFNOTE_FEATURES' as older hypervisor
    parse fields they don't understand as errors and refuse to load
    the kernel. This work-around fixes the problem.
    Signed-off-by: default avatarMukesh Rathor <mukesh.rathor@oracle.com>
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Acked-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
    4e903a20
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