1ff7c5986a
The Xen mapcache is able to create long term mappings, they are called "locked" mappings. The third parameter of the xen_map_cache call specifies if a mapping is a "locked" mapping. >From the QEMU point of view there are two kinds of long term mappings: [a] device memory mappings, such as option roms and video memory [b] dma mappings, created by dma_memory_map & friends After certain operations, ballooning a VM in particular, Xen asks QEMU kindly to destroy all mappings. However, certainly [a] mappings are present and cannot be removed. That's not a problem as they are not affected by balloonning. The *real* problem is that if there are any mappings of type [b], any outstanding dma operations could fail. This is a known shortcoming. In other words, when Xen asks QEMU to destroy all mappings, it is an error if any [b] mappings exist. However today we have no way of distinguishing [a] from [b]. Because of that, we cannot even print a decent warning. This patch introduces a new "dma" bool field to MapCacheRev entires, to remember if a given mapping is for dma or is a long term device memory mapping. When xen_invalidate_map_cache is called, we print a warning if any [b] mappings exist. We ignore [a] mappings. Mappings created by qemu_map_ram_ptr are assumed to be [a], while mappings created by address_space_map->qemu_ram_ptr_length are assumed to be [b]. The goal of the patch is to make debugging and system understanding easier. Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Anthony PERARD <anthony.perard@citrix.com>
56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
/*
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* Copyright (C) 2011 Citrix Ltd.
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef XEN_MAPCACHE_H
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#define XEN_MAPCACHE_H
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typedef hwaddr (*phys_offset_to_gaddr_t)(hwaddr start_addr,
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ram_addr_t size,
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void *opaque);
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#ifdef CONFIG_XEN
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void xen_map_cache_init(phys_offset_to_gaddr_t f,
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void *opaque);
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uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
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uint8_t lock, bool dma);
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ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
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void xen_invalidate_map_cache_entry(uint8_t *buffer);
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void xen_invalidate_map_cache(void);
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#else
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static inline void xen_map_cache_init(phys_offset_to_gaddr_t f,
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void *opaque)
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{
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}
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static inline uint8_t *xen_map_cache(hwaddr phys_addr,
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hwaddr size,
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uint8_t lock,
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bool dma)
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{
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abort();
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}
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static inline ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
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{
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abort();
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}
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static inline void xen_invalidate_map_cache_entry(uint8_t *buffer)
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{
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}
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static inline void xen_invalidate_map_cache(void)
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{
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}
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#endif
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#endif /* XEN_MAPCACHE_H */
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