make DMA ip unmap memory owned by itself

unmapping of the scatter gather attribute memory was done
after the DMA destructor was called, leading to Card trying to
unmap memory that was already freed.
This lead to crashing during cleaning up.

Signed-off-by: Niklas Eiling <niklas.eiling@eonerc.rwth-aachen.de>

fpga/include/villas/fpga/card.hpp

@@ -88,8 +88,8 @@ public:
 	std::shared_ptr<ip::Core>
 	lookupIp(const ip::IpIdentifier &id) const;
 
-	bool
-	mapMemoryBlock(const MemoryBlock &block);
+	bool mapMemoryBlock(const MemoryBlock &block);
+	bool unmapMemoryBlock(const MemoryBlock &block);
 
 private:
 	// Cache a set of already mapped memory blocks

fpga/lib/card.cpp

@@ -218,6 +218,29 @@ std::shared_ptr<ip::Core> PCIeCard::lookupIp(const ip::IpIdentifier &id) const
 	return nullptr;
 }
 
+bool PCIeCard::unmapMemoryBlock(const MemoryBlock &block)
+{
+	if (memoryBlocksMapped.find(block.getAddrSpaceId()) == memoryBlocksMapped.end()) {
+		throw std::runtime_error("Block " + std::to_string(block.getAddrSpaceId()) + " is not mapped but was requested to be unmapped.");
+	}
+
+	auto &mm = MemoryManager::get();
+
+	// Unmap all memory blocks
+	auto translation = mm.getTranslation(addrSpaceIdDeviceToHost, block.getAddrSpaceId());
+
+	const uintptr_t iova = translation.getLocalAddr(0);
+	const size_t size = translation.getSize();
+
+	logger->debug("Unmap block {} at IOVA {:#x} of size {:#x}",
+			block.getAddrSpaceId(), iova, size);
+	vfioContainer->memoryUnmap(iova, size);
+
+	memoryBlocksMapped.erase(block.getAddrSpaceId());
+
+	return true;
+}
+
 bool PCIeCard::mapMemoryBlock(const MemoryBlock &block)
 {
 	if (not vfioContainer->isIommuEnabled()) {

fpga/lib/ips/dma.cpp

@@ -205,6 +205,12 @@ bool Dma::reset()
 
 Dma::~Dma()
 {
+	// Unmap memory in our ownership, MemoryBlock gets deleted and removed from
+	// graph by this destructor as well.
+	if (hasScatterGather()) {
+		card->unmapMemoryBlock(*sgRingTx);
+		card->unmapMemoryBlock(*sgRingRx);
+	}
 	Dma::reset();
 }