185ecf40e3
The data plane thread needs to map guest physical addresses to host pointers. Normally this is done with cpu_physical_memory_map() but the function assumes the global mutex is held. The data plane thread does not touch the global mutex and therefore needs a thread-safe memory mapping mechanism. Hostmem registers a MemoryListener similar to how vhost collects and pushes memory region information into the kernel. There is a fine-grained lock on the regions list which is held during lookup and when installing a new regions list. When the physical memory map changes the MemoryListener callbacks are invoked. They build up a new list of memory regions which is finally installed when the list has been completed. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
58 lines
1.5 KiB
C
58 lines
1.5 KiB
C
/*
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* Thread-safe guest to host memory mapping
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*
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* Copyright 2012 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#ifndef HOSTMEM_H
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#define HOSTMEM_H
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#include "exec/memory.h"
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#include "qemu/thread.h"
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typedef struct {
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void *host_addr;
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hwaddr guest_addr;
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uint64_t size;
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bool readonly;
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} HostMemRegion;
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typedef struct {
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/* The listener is invoked when regions change and a new list of regions is
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* built up completely before they are installed.
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*/
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MemoryListener listener;
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HostMemRegion *new_regions;
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size_t num_new_regions;
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/* Current regions are accessed from multiple threads either to lookup
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* addresses or to install a new list of regions. The lock protects the
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* pointer and the regions.
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*/
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QemuMutex current_regions_lock;
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HostMemRegion *current_regions;
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size_t num_current_regions;
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} HostMem;
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void hostmem_init(HostMem *hostmem);
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void hostmem_finalize(HostMem *hostmem);
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/**
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* Map a guest physical address to a pointer
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*
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* Note that there is map/unmap mechanism here. The caller must ensure that
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* mapped memory is no longer used across events like hot memory unplug. This
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* can be done with other mechanisms like bdrv_drain_all() that quiesce
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* in-flight I/O.
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*/
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void *hostmem_lookup(HostMem *hostmem, hwaddr phys, hwaddr len, bool is_write);
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#endif /* HOSTMEM_H */
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