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This patch integrates three region maps into each PD session to reduce the session overhead and to simplify the PD creation procedure. Please refer to the issue cited below for an elaborative discussion. Note the API change: With this patch, the semantics of core's RM service have changed. Now, the service is merely a tool for creating and destroying managed dataspaces, which are rarely needed. Regular components no longer need a RM session. For this reason, the corresponding argument for the 'Process' and 'Child' constructors has been removed. The former interface of the 'Rm_session' is not named 'Region_map'. As a minor refinement, the 'Fault_type' enum values are now part of the 'Region_map::State' struct. Issue #1938
97 lines
2.6 KiB
C++
97 lines
2.6 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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#include <region_map/client.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 : private Rm_connection, Region_map_client
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{
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Virtual_reservation(addr_t vm_size)
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:
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Region_map_client(Rm_connection::create(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(Region_map_client::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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