src/devices/sysmem/drivers/sysmem/contiguous_pooled_memory_allocator.cc - fuchsia - Git at Google

 // Copyright 2019 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "contiguous_pooled_memory_allocator.h"

 #include <fuchsia/sysmem2/llcpp/fidl.h>
 #include <lib/zx/clock.h>

 #include <ddk/trace/event.h>
 #include <fbl/string_printf.h>

 #include "macros.h"

 namespace sysmem_driver {

 namespace {

 llcpp::fuchsia::sysmem2::HeapProperties BuildHeapProperties(bool is_cpu_accessible) {
   using llcpp::fuchsia::sysmem2::CoherencyDomainSupport;
   using llcpp::fuchsia::sysmem2::HeapProperties;

   auto coherency_domain_support = std::make_unique<CoherencyDomainSupport>();
   *coherency_domain_support =
       CoherencyDomainSupport::Builder(std::make_unique<CoherencyDomainSupport::Frame>())
           .set_cpu_supported(std::make_unique<bool>(is_cpu_accessible))
           .set_ram_supported(std::make_unique<bool>(is_cpu_accessible))
           .set_inaccessible_supported(std::make_unique<bool>(true))
           .build();

   return HeapProperties::Builder(std::make_unique<HeapProperties::Frame>())
       .set_coherency_domain_support(std::move(coherency_domain_support))
       // Contiguous non-protected VMOs need to be cleared.
       .set_need_clear(std::make_unique<bool>(is_cpu_accessible))
       .build();
 }

 }  // namespace

 ContiguousPooledMemoryAllocator::ContiguousPooledMemoryAllocator(
     Owner* parent_device, const char* allocation_name, inspect::Node* parent_node, uint64_t pool_id,
     uint64_t size, bool is_cpu_accessible, bool is_ready, bool can_be_torn_down,
     async_dispatcher_t* dispatcher)
     : MemoryAllocator(BuildHeapProperties(is_cpu_accessible)),
       parent_device_(parent_device),
       allocation_name_(allocation_name),
       pool_id_(pool_id),
       region_allocator_(RegionAllocator::RegionPool::Create(std::numeric_limits<size_t>::max())),
       size_(size),
       is_cpu_accessible_(is_cpu_accessible),
       is_ready_(is_ready),
       can_be_torn_down_(can_be_torn_down) {
   snprintf(child_name_, sizeof(child_name_), "%s-child", allocation_name_);
   // Ensure NUL-terminated.
   child_name_[sizeof(child_name_) - 1] = 0;
   node_ = parent_node->CreateChild(allocation_name);
   size_property_ = node_.CreateUint("size", size);
   high_water_mark_property_ = node_.CreateUint("high_water_mark", 0);
   used_size_property_ = node_.CreateUint("used_size", 0);
   allocations_failed_property_ = node_.CreateUint("allocations_failed", 0);
   last_allocation_failed_timestamp_ns_property_ =
       node_.CreateUint("last_allocation_failed_timestamp_ns", 0);
   allocations_failed_fragmentation_property_ =
       node_.CreateUint("allocations_failed_fragmentation", 0);
   max_free_at_high_water_property_ = node_.CreateUint("max_free_at_high_water", size);

   if (dispatcher) {
     zx_status_t status = zx::event::create(0, &trace_observer_event_);
     ZX_ASSERT(status == ZX_OK);
     status = trace_register_observer(trace_observer_event_.get());
     ZX_ASSERT(status == ZX_OK);
     wait_.set_object(trace_observer_event_.get());
     wait_.set_trigger(ZX_EVENT_SIGNALED);

     status = wait_.Begin(dispatcher);
     ZX_ASSERT(status == ZX_OK);
   }
 }

 ContiguousPooledMemoryAllocator::~ContiguousPooledMemoryAllocator() {
   ZX_DEBUG_ASSERT(is_empty());
   wait_.Cancel();
   if (trace_observer_event_) {
     trace_unregister_observer(trace_observer_event_.get());
   }
 }

 zx_status_t ContiguousPooledMemoryAllocator::Init(uint32_t alignment_log2) {
   zx::vmo local_contiguous_vmo;
   zx_status_t status = zx::vmo::create_contiguous(parent_device_->bti(), size_, alignment_log2,
                                                   &local_contiguous_vmo);
   if (status != ZX_OK) {
     LOG(ERROR, "Could not allocate contiguous memory, status %d allocation_name_: %s", status,
         allocation_name_);
     return status;
   }

   return InitCommon(std::move(local_contiguous_vmo));
 }

 zx_status_t ContiguousPooledMemoryAllocator::InitPhysical(zx_paddr_t paddr) {
   zx::vmo local_contiguous_vmo;
   zx_status_t status = parent_device_->CreatePhysicalVmo(paddr, size_, &local_contiguous_vmo);
   if (status != ZX_OK) {
     LOG(ERROR, "Failed to create physical VMO: %d allocation_name_: %s", status, allocation_name_);
     return status;
   }

   return InitCommon(std::move(local_contiguous_vmo));
 }

 zx_status_t ContiguousPooledMemoryAllocator::InitCommon(zx::vmo local_contiguous_vmo) {
   zx_status_t status =
       local_contiguous_vmo.set_property(ZX_PROP_NAME, allocation_name_, strlen(allocation_name_));
   if (status != ZX_OK) {
     LOG(ERROR, "Failed vmo.set_property(ZX_PROP_NAME, ...): %d", status);
     return status;
   }

   zx_info_vmo_t info;
   status = local_contiguous_vmo.get_info(ZX_INFO_VMO, &info, sizeof(info), nullptr, nullptr);
   if (status != ZX_OK) {
     LOG(ERROR, "Failed local_contiguous_vmo.get_info(ZX_INFO_VMO, ...) - status: %d", status);
     return status;
   }
   // Only secure/protected RAM ever uses a physical VMO.  Not all secure/protected RAM uses a
   // physical VMO.
   ZX_DEBUG_ASSERT(ZX_INFO_VMO_TYPE(info.flags) == ZX_INFO_VMO_TYPE_PAGED || !is_cpu_accessible_);
   // Paged VMOs are cached by default.  Physical VMOs are uncached by default.
   ZX_DEBUG_ASSERT((ZX_INFO_VMO_TYPE(info.flags) == ZX_INFO_VMO_TYPE_PAGED) ==
                   (info.cache_policy == ZX_CACHE_POLICY_CACHED));
   // We'd have this assert, except it doesn't work with fake-bti, so for now we trust that when not
   // running a unit test, we have a VMO with info.flags & ZX_INFO_VMO_CONTIGUOUS.
   // ZX_DEBUG_ASSERT(info.flags & ZX_INFO_VMO_CONTIGUOUS);

   // Regardless of CPU or RAM domain, and regardless of contig VMO or physical VMO, if we use the
   // CPU to access the RAM, we want to use the CPU cache.  If we can't use the CPU to access the RAM
   // (on REE side), then we don't want to use the CPU cache.
   //
   // Why we want cached when is_cpu_accessible_:
   //
   // Without setting cached, in addition to presumably being slower, memcpy tends to fail with
   // non-aligned access faults / syscalls that are trying to copy directly to the VMO can fail
   // without it being obvious that it's an underlying non-aligned access fault triggered by memcpy.
   //
   // Why we want uncached when !is_cpu_accessible_:
   //
   // IIUC, it's possible on aarch64 for a cached mapping to protected memory + speculative execution
   // to cause random faults, while a non-cached mapping only faults if a non-cached mapping is
   // actually touched.
   uint32_t desired_cache_policy =
       is_cpu_accessible_ ? ZX_CACHE_POLICY_CACHED : ZX_CACHE_POLICY_UNCACHED;
   if (info.cache_policy != desired_cache_policy) {
     status = local_contiguous_vmo.set_cache_policy(desired_cache_policy);
     if (status != ZX_OK) {
       // TODO(fxbug.dev/34580): Ideally we'd set ZX_CACHE_POLICY_UNCACHED when !is_cpu_accessible_,
       // since IIUC on aarch64 it's possible for a cached mapping to secure/protected memory +
       // speculative execution to cause random faults, while an uncached mapping only faults if the
       // uncached mapping is actually touched.  However, currently for a VMO created with
       // zx::vmo::create_contiguous(), the .set_cache_policy() doesn't work because the VMO already
       // has pages.  Cases where !is_cpu_accessible_ include both Init() and InitPhysical(), so we
       // can't rely on local_contiguous_vmo being a physical VMO.
       if (ZX_INFO_VMO_TYPE(info.flags) == ZX_INFO_VMO_TYPE_PAGED) {
         LOG(ERROR,
             "Ignoring failure to set_cache_policy() on contig VMO - see fxbug.dev/34580 - status: "
             "%d",
             status);
         status = ZX_OK;
         goto keepGoing;
       }
       LOG(ERROR, "Failed to set_cache_policy(): %d", status);
       return status;
     }
   }
 keepGoing:;

   zx_paddr_t addrs;
   // When running a unit test, the src/devices/testing/fake-bti provides a fake zx_bti_pin() that
   // should tolerate ZX_BTI_CONTIGUOUS here despite the local_contiguous_vmo not actually having
   // info.flags ZX_INFO_VMO_CONTIGUOUS.
   status = parent_device_->bti().pin(ZX_BTI_PERM_READ | ZX_BTI_PERM_WRITE | ZX_BTI_CONTIGUOUS,
                                      local_contiguous_vmo, 0, size_, &addrs, 1, &pool_pmt_);
   if (status != ZX_OK) {
     LOG(ERROR, "Could not pin memory, status %d", status);
     return status;
   }

   start_ = addrs;
   contiguous_vmo_ = std::move(local_contiguous_vmo);
   ralloc_region_t region = {0, size_};
   region_allocator_.AddRegion(region);
   // It is intentional here that ~pmt doesn't imply zx_pmt_unpin().  If sysmem dies, we'll reboot.
   return ZX_OK;
 }

 zx_status_t ContiguousPooledMemoryAllocator::Allocate(uint64_t size,
                                                       std::optional<std::string> name,
                                                       zx::vmo* parent_vmo) {
   if (!is_ready_) {
     LOG(ERROR, "allocation_name_: %s is not ready_, failing", allocation_name_);
     return ZX_ERR_BAD_STATE;
   }
   RegionAllocator::Region::UPtr region;
   zx::vmo result_parent_vmo;

   // TODO(fxbug.dev/43184): Use a fragmentation-reducing allocator (such as best fit).
   //
   // The "region" param is an out ref.
   zx_status_t status = region_allocator_.GetRegion(size, ZX_PAGE_SIZE, region);
   if (status != ZX_OK) {
     LOG(WARNING, "GetRegion failed (out of space?) - size: %zu status: %d", size, status);
     DumpPoolStats();
     allocations_failed_property_.Add(1);
     last_allocation_failed_timestamp_ns_property_.Set(zx::clock::get_monotonic().get());
     uint64_t unused_size = 0;
     region_allocator_.WalkAvailableRegions([&unused_size](const ralloc_region_t* r) -> bool {
       unused_size += r->size;
       return true;
     });
     if (unused_size >= size) {
       // There's enough unused memory total, so the allocation must have failed due to
       // fragmentation.
       allocations_failed_fragmentation_property_.Add(1);
     }
     return status;
   }

   TracePoolSize(false);

   // The result_parent_vmo created here is a VMO window to a sub-region of contiguous_vmo_.
   status = contiguous_vmo_.create_child(ZX_VMO_CHILD_SLICE, region->base, size, &result_parent_vmo);
   if (status != ZX_OK) {
     LOG(ERROR, "Failed vmo.create_child(ZX_VMO_CHILD_SLICE, ...): %d", status);
     return status;
   }

   // If you see a Sysmem*-child VMO you should know that it doesn't actually
   // take up any space, because the same memory is backed by contiguous_vmo_.
   status = result_parent_vmo.set_property(ZX_PROP_NAME, child_name_, strlen(child_name_));
   if (status != ZX_OK) {
     LOG(ERROR, "Failed vmo.set_property(ZX_PROP_NAME, ...): %d", status);
     return status;
   }

   if (!name) {
     name = "Unknown";
   }

   RegionData data;
   data.name = std::move(*name);
   zx_info_handle_basic_t handle_info;
   status = result_parent_vmo.get_info(ZX_INFO_HANDLE_BASIC, &handle_info, sizeof(handle_info),
                                       nullptr, nullptr);
   ZX_ASSERT(status == ZX_OK);
   data.node = node_.CreateChild(fbl::StringPrintf("vmo-%ld", handle_info.koid).c_str());
   data.size_property = data.node.CreateUint("size", size);
   data.koid = handle_info.koid;
   data.koid_property = data.node.CreateUint("koid", handle_info.koid);
   data.ptr = std::move(region);
   regions_.emplace(std::make_pair(result_parent_vmo.get(), std::move(data)));

   *parent_vmo = std::move(result_parent_vmo);
   return ZX_OK;
 }

 zx_status_t ContiguousPooledMemoryAllocator::SetupChildVmo(
     const zx::vmo& parent_vmo, const zx::vmo& child_vmo,
     llcpp::fuchsia::sysmem2::SingleBufferSettings buffer_settings) {
   // nothing to do here
   return ZX_OK;
 }

 void ContiguousPooledMemoryAllocator::Delete(zx::vmo parent_vmo) {
   TRACE_DURATION("gfx", "ContiguousPooledMemoryAllocator::Delete");
   auto it = regions_.find(parent_vmo.get());
   ZX_ASSERT(it != regions_.end());
   regions_.erase(it);
   parent_vmo.reset();
   TracePoolSize(false);
   if (is_empty()) {
     parent_device_->CheckForUnbind();
   }
 }

 void ContiguousPooledMemoryAllocator::set_ready() { is_ready_ = true; }

 bool ContiguousPooledMemoryAllocator::is_ready() { return is_ready_; }

 void ContiguousPooledMemoryAllocator::TraceObserverCallback(async_dispatcher_t* dispatcher,
                                                             async::WaitBase* wait,
                                                             zx_status_t status,
                                                             const zx_packet_signal_t* signal) {
   if (status != ZX_OK)
     return;
   trace_observer_event_.signal(ZX_EVENT_SIGNALED, 0);
   // We don't care if tracing was enabled or disabled - if the category is now disabled, the trace
   // will just be ignored anyway.
   TracePoolSize(true);

   trace_notify_observer_updated(trace_observer_event_.get());
   wait_.Begin(dispatcher);
 }

 void ContiguousPooledMemoryAllocator::DumpPoolStats() {
   uint64_t unused_size = 0;
   uint64_t max_free_size = 0;
   region_allocator_.WalkAvailableRegions(
       [&unused_size, &max_free_size](const ralloc_region_t* r) -> bool {
         unused_size += r->size;
         max_free_size = std::max(max_free_size, r->size);
         return true;
       });

   LOG(INFO,
       "%s unused total: %ld bytes, max free size %ld bytes "
       "AllocatedRegionCount(): %zu AvailableRegionCount(): %zu",
       allocation_name_, unused_size, max_free_size, region_allocator_.AllocatedRegionCount(),
       region_allocator_.AvailableRegionCount());
   for (auto& [vmo, region] : regions_) {
     LOG(INFO, "Region koid %ld name %s size %zu", region.koid, region.name.c_str(),
         region.ptr->size);
   }
 }

 void ContiguousPooledMemoryAllocator::DumpPoolHighWaterMark() {
   LOG(INFO,
       "%s high_water_mark_used_size_: %ld bytes, max_free_size_at_high_water_mark_ %ld bytes "
       "(not including any failed allocations)",
       allocation_name_, high_water_mark_used_size_, max_free_size_at_high_water_mark_);
 }

 void ContiguousPooledMemoryAllocator::TracePoolSize(bool initial_trace) {
   uint64_t used_size = 0;
   region_allocator_.WalkAllocatedRegions([&used_size](const ralloc_region_t* r) -> bool {
     used_size += r->size;
     return true;
   });
   used_size_property_.Set(used_size);
   TRACE_COUNTER("gfx", "Contiguous pool size", pool_id_, "size", used_size);
   bool trace_high_water_mark = initial_trace;
   if (used_size > high_water_mark_used_size_) {
     high_water_mark_used_size_ = used_size;
     trace_high_water_mark = true;
     high_water_mark_property_.Set(high_water_mark_used_size_);
     uint64_t max_free_size = 0;
     region_allocator_.WalkAvailableRegions([&max_free_size](const ralloc_region_t* r) -> bool {
       max_free_size = std::max(max_free_size, r->size);
       return true;
     });
     max_free_size_at_high_water_mark_ = max_free_size;
     max_free_at_high_water_property_.Set(max_free_size_at_high_water_mark_);
     // This can be a bit noisy at first, but then settles down quickly.
     DumpPoolHighWaterMark();
   }
   if (trace_high_water_mark) {
     TRACE_INSTANT("gfx", "Increased high water mark", TRACE_SCOPE_THREAD, "allocation_name",
                   allocation_name_, "size", high_water_mark_used_size_);
   }
 }

 }  // namespace sysmem_driver
	// Copyright 2019 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "contiguous_pooled_memory_allocator.h"

	#include <fuchsia/sysmem2/llcpp/fidl.h>
	#include <lib/zx/clock.h>

	#include <ddk/trace/event.h>
	#include <fbl/string_printf.h>

	#include "macros.h"

	namespace sysmem_driver {

	namespace {

	llcpp::fuchsia::sysmem2::HeapProperties BuildHeapProperties(bool is_cpu_accessible) {
	using llcpp::fuchsia::sysmem2::CoherencyDomainSupport;
	using llcpp::fuchsia::sysmem2::HeapProperties;

	auto coherency_domain_support = std::make_unique<CoherencyDomainSupport>();
	*coherency_domain_support =
	CoherencyDomainSupport::Builder(std::make_unique<CoherencyDomainSupport::Frame>())
	.set_cpu_supported(std::make_unique<bool>(is_cpu_accessible))
	.set_ram_supported(std::make_unique<bool>(is_cpu_accessible))
	.set_inaccessible_supported(std::make_unique<bool>(true))
	.build();

	return HeapProperties::Builder(std::make_unique<HeapProperties::Frame>())
	.set_coherency_domain_support(std::move(coherency_domain_support))
	// Contiguous non-protected VMOs need to be cleared.
	.set_need_clear(std::make_unique<bool>(is_cpu_accessible))
	.build();
	}

	} // namespace

	ContiguousPooledMemoryAllocator::ContiguousPooledMemoryAllocator(
	Owner* parent_device, const char* allocation_name, inspect::Node* parent_node, uint64_t pool_id,
	uint64_t size, bool is_cpu_accessible, bool is_ready, bool can_be_torn_down,
	async_dispatcher_t* dispatcher)
	: MemoryAllocator(BuildHeapProperties(is_cpu_accessible)),
	parent_device_(parent_device),
	allocation_name_(allocation_name),
	pool_id_(pool_id),
	region_allocator_(RegionAllocator::RegionPool::Create(std::numeric_limits<size_t>::max())),
	size_(size),
	is_cpu_accessible_(is_cpu_accessible),
	is_ready_(is_ready),
	can_be_torn_down_(can_be_torn_down) {
	snprintf(child_name_, sizeof(child_name_), "%s-child", allocation_name_);
	// Ensure NUL-terminated.
	child_name_[sizeof(child_name_) - 1] = 0;
	node_ = parent_node->CreateChild(allocation_name);
	size_property_ = node_.CreateUint("size", size);
	high_water_mark_property_ = node_.CreateUint("high_water_mark", 0);
	used_size_property_ = node_.CreateUint("used_size", 0);
	allocations_failed_property_ = node_.CreateUint("allocations_failed", 0);
	last_allocation_failed_timestamp_ns_property_ =
	node_.CreateUint("last_allocation_failed_timestamp_ns", 0);
	allocations_failed_fragmentation_property_ =
	node_.CreateUint("allocations_failed_fragmentation", 0);
	max_free_at_high_water_property_ = node_.CreateUint("max_free_at_high_water", size);

	if (dispatcher) {
	zx_status_t status = zx::event::create(0, &trace_observer_event_);
	ZX_ASSERT(status == ZX_OK);
	status = trace_register_observer(trace_observer_event_.get());
	ZX_ASSERT(status == ZX_OK);
	wait_.set_object(trace_observer_event_.get());
	wait_.set_trigger(ZX_EVENT_SIGNALED);

	status = wait_.Begin(dispatcher);
	ZX_ASSERT(status == ZX_OK);
	}
	}

	ContiguousPooledMemoryAllocator::~ContiguousPooledMemoryAllocator() {
	ZX_DEBUG_ASSERT(is_empty());
	wait_.Cancel();
	if (trace_observer_event_) {
	trace_unregister_observer(trace_observer_event_.get());
	}
	}

	zx_status_t ContiguousPooledMemoryAllocator::Init(uint32_t alignment_log2) {
	zx::vmo local_contiguous_vmo;
	zx_status_t status = zx::vmo::create_contiguous(parent_device_->bti(), size_, alignment_log2,
	&local_contiguous_vmo);
	if (status != ZX_OK) {
	LOG(ERROR, "Could not allocate contiguous memory, status %d allocation_name_: %s", status,
	allocation_name_);
	return status;
	}

	return InitCommon(std::move(local_contiguous_vmo));
	}

	zx_status_t ContiguousPooledMemoryAllocator::InitPhysical(zx_paddr_t paddr) {
	zx::vmo local_contiguous_vmo;
	zx_status_t status = parent_device_->CreatePhysicalVmo(paddr, size_, &local_contiguous_vmo);
	if (status != ZX_OK) {
	LOG(ERROR, "Failed to create physical VMO: %d allocation_name_: %s", status, allocation_name_);
	return status;
	}

	return InitCommon(std::move(local_contiguous_vmo));
	}

	zx_status_t ContiguousPooledMemoryAllocator::InitCommon(zx::vmo local_contiguous_vmo) {
	zx_status_t status =
	local_contiguous_vmo.set_property(ZX_PROP_NAME, allocation_name_, strlen(allocation_name_));
	if (status != ZX_OK) {
	LOG(ERROR, "Failed vmo.set_property(ZX_PROP_NAME, ...): %d", status);
	return status;
	}

	zx_info_vmo_t info;
	status = local_contiguous_vmo.get_info(ZX_INFO_VMO, &info, sizeof(info), nullptr, nullptr);
	if (status != ZX_OK) {
	LOG(ERROR, "Failed local_contiguous_vmo.get_info(ZX_INFO_VMO, ...) - status: %d", status);
	return status;
	}
	// Only secure/protected RAM ever uses a physical VMO. Not all secure/protected RAM uses a
	// physical VMO.
	ZX_DEBUG_ASSERT(ZX_INFO_VMO_TYPE(info.flags) == ZX_INFO_VMO_TYPE_PAGED \|\| !is_cpu_accessible_);
	// Paged VMOs are cached by default. Physical VMOs are uncached by default.
	ZX_DEBUG_ASSERT((ZX_INFO_VMO_TYPE(info.flags) == ZX_INFO_VMO_TYPE_PAGED) ==
	(info.cache_policy == ZX_CACHE_POLICY_CACHED));
	// We'd have this assert, except it doesn't work with fake-bti, so for now we trust that when not
	// running a unit test, we have a VMO with info.flags & ZX_INFO_VMO_CONTIGUOUS.
	// ZX_DEBUG_ASSERT(info.flags & ZX_INFO_VMO_CONTIGUOUS);

	// Regardless of CPU or RAM domain, and regardless of contig VMO or physical VMO, if we use the
	// CPU to access the RAM, we want to use the CPU cache. If we can't use the CPU to access the RAM
	// (on REE side), then we don't want to use the CPU cache.
	//
	// Why we want cached when is_cpu_accessible_:
	//
	// Without setting cached, in addition to presumably being slower, memcpy tends to fail with
	// non-aligned access faults / syscalls that are trying to copy directly to the VMO can fail
	// without it being obvious that it's an underlying non-aligned access fault triggered by memcpy.
	//
	// Why we want uncached when !is_cpu_accessible_:
	//
	// IIUC, it's possible on aarch64 for a cached mapping to protected memory + speculative execution
	// to cause random faults, while a non-cached mapping only faults if a non-cached mapping is
	// actually touched.
	uint32_t desired_cache_policy =
	is_cpu_accessible_ ? ZX_CACHE_POLICY_CACHED : ZX_CACHE_POLICY_UNCACHED;
	if (info.cache_policy != desired_cache_policy) {
	status = local_contiguous_vmo.set_cache_policy(desired_cache_policy);
	if (status != ZX_OK) {
	// TODO(fxbug.dev/34580): Ideally we'd set ZX_CACHE_POLICY_UNCACHED when !is_cpu_accessible_,
	// since IIUC on aarch64 it's possible for a cached mapping to secure/protected memory +
	// speculative execution to cause random faults, while an uncached mapping only faults if the
	// uncached mapping is actually touched. However, currently for a VMO created with
	// zx::vmo::create_contiguous(), the .set_cache_policy() doesn't work because the VMO already
	// has pages. Cases where !is_cpu_accessible_ include both Init() and InitPhysical(), so we
	// can't rely on local_contiguous_vmo being a physical VMO.
	if (ZX_INFO_VMO_TYPE(info.flags) == ZX_INFO_VMO_TYPE_PAGED) {
	LOG(ERROR,
	"Ignoring failure to set_cache_policy() on contig VMO - see fxbug.dev/34580 - status: "
	"%d",
	status);
	status = ZX_OK;
	goto keepGoing;
	}
	LOG(ERROR, "Failed to set_cache_policy(): %d", status);
	return status;
	}
	}
	keepGoing:;

	zx_paddr_t addrs;
	// When running a unit test, the src/devices/testing/fake-bti provides a fake zx_bti_pin() that
	// should tolerate ZX_BTI_CONTIGUOUS here despite the local_contiguous_vmo not actually having
	// info.flags ZX_INFO_VMO_CONTIGUOUS.
	status = parent_device_->bti().pin(ZX_BTI_PERM_READ \| ZX_BTI_PERM_WRITE \| ZX_BTI_CONTIGUOUS,
	local_contiguous_vmo, 0, size_, &addrs, 1, &pool_pmt_);
	if (status != ZX_OK) {
	LOG(ERROR, "Could not pin memory, status %d", status);
	return status;
	}

	start_ = addrs;
	contiguous_vmo_ = std::move(local_contiguous_vmo);
	ralloc_region_t region = {0, size_};
	region_allocator_.AddRegion(region);
	// It is intentional here that ~pmt doesn't imply zx_pmt_unpin(). If sysmem dies, we'll reboot.
	return ZX_OK;
	}

	zx_status_t ContiguousPooledMemoryAllocator::Allocate(uint64_t size,
	std::optional<std::string> name,
	zx::vmo* parent_vmo) {
	if (!is_ready_) {
	LOG(ERROR, "allocation_name_: %s is not ready_, failing", allocation_name_);
	return ZX_ERR_BAD_STATE;
	}
	RegionAllocator::Region::UPtr region;
	zx::vmo result_parent_vmo;

	// TODO(fxbug.dev/43184): Use a fragmentation-reducing allocator (such as best fit).
	//
	// The "region" param is an out ref.
	zx_status_t status = region_allocator_.GetRegion(size, ZX_PAGE_SIZE, region);
	if (status != ZX_OK) {
	LOG(WARNING, "GetRegion failed (out of space?) - size: %zu status: %d", size, status);
	DumpPoolStats();
	allocations_failed_property_.Add(1);
	last_allocation_failed_timestamp_ns_property_.Set(zx::clock::get_monotonic().get());
	uint64_t unused_size = 0;
	region_allocator_.WalkAvailableRegions([&unused_size](const ralloc_region_t* r) -> bool {
	unused_size += r->size;
	return true;
	});
	if (unused_size >= size) {
	// There's enough unused memory total, so the allocation must have failed due to
	// fragmentation.
	allocations_failed_fragmentation_property_.Add(1);
	}
	return status;
	}

	TracePoolSize(false);

	// The result_parent_vmo created here is a VMO window to a sub-region of contiguous_vmo_.
	status = contiguous_vmo_.create_child(ZX_VMO_CHILD_SLICE, region->base, size, &result_parent_vmo);
	if (status != ZX_OK) {
	LOG(ERROR, "Failed vmo.create_child(ZX_VMO_CHILD_SLICE, ...): %d", status);
	return status;
	}

	// If you see a Sysmem*-child VMO you should know that it doesn't actually
	// take up any space, because the same memory is backed by contiguous_vmo_.
	status = result_parent_vmo.set_property(ZX_PROP_NAME, child_name_, strlen(child_name_));
	if (status != ZX_OK) {
	LOG(ERROR, "Failed vmo.set_property(ZX_PROP_NAME, ...): %d", status);
	return status;
	}

	if (!name) {
	name = "Unknown";
	}

	RegionData data;
	data.name = std::move(*name);
	zx_info_handle_basic_t handle_info;
	status = result_parent_vmo.get_info(ZX_INFO_HANDLE_BASIC, &handle_info, sizeof(handle_info),
	nullptr, nullptr);
	ZX_ASSERT(status == ZX_OK);
	data.node = node_.CreateChild(fbl::StringPrintf("vmo-%ld", handle_info.koid).c_str());
	data.size_property = data.node.CreateUint("size", size);
	data.koid = handle_info.koid;
	data.koid_property = data.node.CreateUint("koid", handle_info.koid);
	data.ptr = std::move(region);
	regions_.emplace(std::make_pair(result_parent_vmo.get(), std::move(data)));

	*parent_vmo = std::move(result_parent_vmo);
	return ZX_OK;
	}

	zx_status_t ContiguousPooledMemoryAllocator::SetupChildVmo(
	const zx::vmo& parent_vmo, const zx::vmo& child_vmo,
	llcpp::fuchsia::sysmem2::SingleBufferSettings buffer_settings) {
	// nothing to do here
	return ZX_OK;
	}

	void ContiguousPooledMemoryAllocator::Delete(zx::vmo parent_vmo) {
	TRACE_DURATION("gfx", "ContiguousPooledMemoryAllocator::Delete");
	auto it = regions_.find(parent_vmo.get());
	ZX_ASSERT(it != regions_.end());
	regions_.erase(it);
	parent_vmo.reset();
	TracePoolSize(false);
	if (is_empty()) {
	parent_device_->CheckForUnbind();
	}
	}

	void ContiguousPooledMemoryAllocator::set_ready() { is_ready_ = true; }

	bool ContiguousPooledMemoryAllocator::is_ready() { return is_ready_; }

	void ContiguousPooledMemoryAllocator::TraceObserverCallback(async_dispatcher_t* dispatcher,
	async::WaitBase* wait,
	zx_status_t status,
	const zx_packet_signal_t* signal) {
	if (status != ZX_OK)
	return;
	trace_observer_event_.signal(ZX_EVENT_SIGNALED, 0);
	// We don't care if tracing was enabled or disabled - if the category is now disabled, the trace
	// will just be ignored anyway.
	TracePoolSize(true);

	trace_notify_observer_updated(trace_observer_event_.get());
	wait_.Begin(dispatcher);
	}

	void ContiguousPooledMemoryAllocator::DumpPoolStats() {
	uint64_t unused_size = 0;
	uint64_t max_free_size = 0;
	region_allocator_.WalkAvailableRegions(
	[&unused_size, &max_free_size](const ralloc_region_t* r) -> bool {
	unused_size += r->size;
	max_free_size = std::max(max_free_size, r->size);
	return true;
	});

	LOG(INFO,
	"%s unused total: %ld bytes, max free size %ld bytes "
	"AllocatedRegionCount(): %zu AvailableRegionCount(): %zu",
	allocation_name_, unused_size, max_free_size, region_allocator_.AllocatedRegionCount(),
	region_allocator_.AvailableRegionCount());
	for (auto& [vmo, region] : regions_) {
	LOG(INFO, "Region koid %ld name %s size %zu", region.koid, region.name.c_str(),
	region.ptr->size);
	}
	}

	void ContiguousPooledMemoryAllocator::DumpPoolHighWaterMark() {
	LOG(INFO,
	"%s high_water_mark_used_size_: %ld bytes, max_free_size_at_high_water_mark_ %ld bytes "
	"(not including any failed allocations)",
	allocation_name_, high_water_mark_used_size_, max_free_size_at_high_water_mark_);
	}

	void ContiguousPooledMemoryAllocator::TracePoolSize(bool initial_trace) {
	uint64_t used_size = 0;
	region_allocator_.WalkAllocatedRegions([&used_size](const ralloc_region_t* r) -> bool {
	used_size += r->size;
	return true;
	});
	used_size_property_.Set(used_size);
	TRACE_COUNTER("gfx", "Contiguous pool size", pool_id_, "size", used_size);
	bool trace_high_water_mark = initial_trace;
	if (used_size > high_water_mark_used_size_) {
	high_water_mark_used_size_ = used_size;
	trace_high_water_mark = true;
	high_water_mark_property_.Set(high_water_mark_used_size_);
	uint64_t max_free_size = 0;
	region_allocator_.WalkAvailableRegions([&max_free_size](const ralloc_region_t* r) -> bool {
	max_free_size = std::max(max_free_size, r->size);
	return true;
	});
	max_free_size_at_high_water_mark_ = max_free_size;
	max_free_at_high_water_property_.Set(max_free_size_at_high_water_mark_);
	// This can be a bit noisy at first, but then settles down quickly.
	DumpPoolHighWaterMark();
	}
	if (trace_high_water_mark) {
	TRACE_INSTANT("gfx", "Increased high water mark", TRACE_SCOPE_THREAD, "allocation_name",
	allocation_name_, "size", high_water_mark_used_size_);
	}
	}

	} // namespace sysmem_driver