96 lines
2.5 KiB
C++
96 lines
2.5 KiB
C++
/*
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* \brief Utilities for implementing VMMs on Genode/NOVA
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* \author Norman Feske
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* \date 2013-08-20
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*
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* The VMM and the guest share the same PD. However, the guest's view on the PD
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* is restricted to the guest-physical-to-VMM-local mappings installed by the
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* VMM for the VCPU's EC.
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*
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* The guest memory is shadowed at the lower portion of the VMM's address
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* space. If the guest (the VCPU EC) tries to access a page that has no mapping
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* in the VMM's PD, NOVA does not generate a page-fault (which would be
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* delivered to the pager of the VMM, i.e., core) but it produces a NPT
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* virtualization event handled locally by the VMM. The NPT event handler is
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* the '_svm_npt' function.
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*/
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/*
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* Copyright (C) 2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__VMM__GUEST_MEMORY_H_
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#define _INCLUDE__VMM__GUEST_MEMORY_H_
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/* Genode includes */
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#include <os/attached_ram_dataspace.h>
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#include <rm_session/connection.h>
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/* VMM utilities includes */
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#include <vmm/types.h>
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namespace Vmm {
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using namespace Genode;
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class Virtual_reservation;
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class Guest_memory;
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}
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/**
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* The 'Virtual_reservation' is a managed dataspace that occupies the lower
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* part of the address space, which contains the shadow of the VCPU's physical
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* memory.
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*/
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struct Vmm::Virtual_reservation : Rm_connection
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{
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Virtual_reservation(addr_t vm_size)
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:
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Rm_connection(0, vm_size)
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{
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try {
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/*
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* Attach reservation to the beginning of the local address
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* space. We leave out the very first page because core denies
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* the attachment of anything at the zero page.
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*/
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env()->rm_session()->attach_at(Rm_connection::dataspace(),
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PAGE_SIZE, 0, PAGE_SIZE);
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} catch (Rm_session::Region_conflict) {
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PERR("region conflict while attaching guest-physical memory");
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}
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}
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~Virtual_reservation()
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{
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env()->rm_session()->detach((void *)PAGE_SIZE);
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}
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};
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/**
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* Representation of guest memory
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*
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*/
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struct Vmm::Guest_memory : Attached_ram_dataspace
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{
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/**
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* Constructor
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*
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* \param backing_store_size number of bytes of physical RAM to be
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* used as guest-physical and device memory,
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* allocated from core's RAM service
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*/
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Guest_memory(size_t backing_store_size)
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:
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Attached_ram_dataspace(env()->ram_session(), backing_store_size)
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{ }
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};
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#endif /* _INCLUDE__VMM__GUEST_MEMORY_H_ */
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