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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> |
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| .. | ||
| accel.h | ||
| arch_init.h | ||
| balloon.h | ||
| block-backend.h | ||
| blockdev.h | ||
| bt.h | ||
| char.h | ||
| cpus.h | ||
| cryptodev.h | ||
| device_tree.h | ||
| dma.h | ||
| dump-arch.h | ||
| dump.h | ||
| hax.h | ||
| hostmem.h | ||
| hw_accel.h | ||
| iothread.h | ||
| kvm.h | ||
| kvm_int.h | ||
| memory_mapping.h | ||
| numa.h | ||
| os-posix.h | ||
| os-win32.h | ||
| qtest.h | ||
| replay.h | ||
| reset.h | ||
| rng-random.h | ||
| rng.h | ||
| seccomp.h | ||
| sysemu.h | ||
| tpm.h | ||
| tpm_backend.h | ||
| tpm_backend_int.h | ||
| watchdog.h | ||
| xen-mapcache.h | ||