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Kernel: Move VirtIO code away from using a scatter gather list
Currently, when passing buffers into VirtIOQueues, we use scatter-gather lists, which contain an internal vector of buffers. This vector is allocated, filled and the destroy whenever we try to provide buffers into a virtqueue, which would happen a lot in performance cricital code (the main transport mechanism for certain paravirtualized devices). This commit moves it over to using VirtIOQueueChains and building the chain in place in the VirtIOQueue. Also included are a bunch of fixups for the VirtIO Console device, making it use an internal VM::RingBuffer instead.
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parent
13d5cdcd08
commit
ed0e7b53a5
11 changed files with 312 additions and 159 deletions
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@ -19,40 +19,4 @@ ScatterGatherList::ScatterGatherList(AsyncBlockDeviceRequest& request, NonnullRe
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m_dma_region = MM.allocate_kernel_region_with_vmobject(m_vm_object, page_round_up((request.block_count() * device_block_size)), "AHCI Scattered DMA", Region::Access::Read | Region::Access::Write, Region::Cacheable::Yes);
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}
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ScatterGatherRefList ScatterGatherRefList::create_from_buffer(const u8* buffer, size_t size)
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{
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VERIFY(buffer && size);
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ScatterGatherRefList new_list;
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auto* region = MM.find_region_from_vaddr(VirtualAddress(buffer));
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VERIFY(region);
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while (size > 0) {
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size_t offset_in_page = (VirtualAddress(buffer) - region->vaddr()).get() % PAGE_SIZE;
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size_t size_in_page = min(PAGE_SIZE - offset_in_page, size);
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VERIFY(offset_in_page + size_in_page - 1 <= PAGE_SIZE);
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new_list.add_entry(region->physical_page(region->page_index_from_address(VirtualAddress(buffer)))->paddr().get(), offset_in_page, size_in_page);
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size -= size_in_page;
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buffer += size_in_page;
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}
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return new_list;
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}
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ScatterGatherRefList ScatterGatherRefList::create_from_physical(PhysicalAddress paddr, size_t size)
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{
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VERIFY(!paddr.is_null() && size);
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ScatterGatherRefList new_list;
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new_list.add_entry(paddr.page_base().get(), paddr.offset_in_page(), size);
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return new_list;
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}
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void ScatterGatherRefList::add_entry(FlatPtr addr, size_t offset, size_t size)
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{
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m_entries.append({ addr, offset, size });
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}
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void ScatterGatherRefList::for_each_entry(Function<void(const FlatPtr, const size_t)> callback) const
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{
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for (auto& entry : m_entries)
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callback(entry.page_base + entry.offset, entry.length);
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}
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}
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