From 7f85abb28120fbb57bb813b828ee42f2a2031990 Mon Sep 17 00:00:00 2001
From: Markus Wick <markus@selfnet.de>
Date: Fri, 11 Jun 2021 11:47:23 +0200
Subject: [PATCH] common/host_memory: Implement a fallback if fastmem fails.
This falls back to the old approach of using a virtual buffer.
Windows is untested, but this build should fix support for Windows < 10 v1803. However without fastmem support at all.
---
src/common/host_memory.cpp | 59 +++++++++++++++++++++++++++++---------
src/common/host_memory.h | 4 +++
2 files changed, 49 insertions(+), 14 deletions(-)
diff --git a/src/common/host_memory.cpp b/src/common/host_memory.cpp
index 9ae384f01c..8bd70abc79 100644
--- a/src/common/host_memory.cpp
+++ b/src/common/host_memory.cpp
@@ -449,21 +449,52 @@ private:
int fd{-1}; // memfd file descriptor, -1 is the error value of memfd_create
};
-#else // ^^^ Linux ^^^
+#else // ^^^ Linux ^^^ vvv Generic vvv
-#error Please implement the host memory for your platform
+class HostMemory::Impl {
+public:
+ explicit Impl(size_t /*backing_size */, size_t /* virtual_size */) {
+ // This is just a place holder.
+ // Please implement fastmem in a propper way on your platform.
+ throw std::bad_alloc{};
+ }
-#endif
+ void Map(size_t virtual_offset, size_t host_offset, size_t length) {}
+
+ void Unmap(size_t virtual_offset, size_t length) {}
+
+ void Protect(size_t virtual_offset, size_t length, bool read, bool write) {}
+
+ u8* backing_base{nullptr};
+ u8* virtual_base{nullptr};
+};
+
+#endif // ^^^ Generic ^^^
HostMemory::HostMemory(size_t backing_size_, size_t virtual_size_)
- : backing_size(backing_size_),
- virtual_size(virtual_size_), impl{std::make_unique<HostMemory::Impl>(
- AlignUp(backing_size, PageAlignment),
- AlignUp(virtual_size, PageAlignment) + 3 * HugePageSize)},
- backing_base{impl->backing_base}, virtual_base{impl->virtual_base} {
- virtual_base += 2 * HugePageSize - 1;
- virtual_base -= reinterpret_cast<size_t>(virtual_base) & (HugePageSize - 1);
- virtual_base_offset = virtual_base - impl->virtual_base;
+ : backing_size(backing_size_), virtual_size(virtual_size_) {
+ try {
+ // Try to allocate a fastmem arena.
+ // The implementation will fail with std::bad_alloc on errors.
+ impl = std::make_unique<HostMemory::Impl>(AlignUp(backing_size, PageAlignment),
+ AlignUp(virtual_size, PageAlignment) +
+ 3 * HugePageSize);
+ backing_base = impl->backing_base;
+ virtual_base = impl->virtual_base;
+
+ if (virtual_base) {
+ virtual_base += 2 * HugePageSize - 1;
+ virtual_base -= reinterpret_cast<size_t>(virtual_base) & (HugePageSize - 1);
+ virtual_base_offset = virtual_base - impl->virtual_base;
+ }
+
+ } catch (const std::bad_alloc&) {
+ LOG_CRITICAL(HW_Memory,
+ "Fastmem unavailable, falling back to VirtualBuffer for memory allocation");
+ fallback_buffer = std::make_unique<Common::VirtualBuffer<u8>>(backing_size);
+ backing_base = fallback_buffer->data();
+ virtual_base = nullptr;
+ }
}
HostMemory::~HostMemory() = default;
@@ -478,7 +509,7 @@ void HostMemory::Map(size_t virtual_offset, size_t host_offset, size_t length) {
ASSERT(length % PageAlignment == 0);
ASSERT(virtual_offset + length <= virtual_size);
ASSERT(host_offset + length <= backing_size);
- if (length == 0) {
+ if (length == 0 || !virtual_base || !impl) {
return;
}
impl->Map(virtual_offset + virtual_base_offset, host_offset, length);
@@ -488,7 +519,7 @@ void HostMemory::Unmap(size_t virtual_offset, size_t length) {
ASSERT(virtual_offset % PageAlignment == 0);
ASSERT(length % PageAlignment == 0);
ASSERT(virtual_offset + length <= virtual_size);
- if (length == 0) {
+ if (length == 0 || !virtual_base || !impl) {
return;
}
impl->Unmap(virtual_offset + virtual_base_offset, length);
@@ -498,7 +529,7 @@ void HostMemory::Protect(size_t virtual_offset, size_t length, bool read, bool w
ASSERT(virtual_offset % PageAlignment == 0);
ASSERT(length % PageAlignment == 0);
ASSERT(virtual_offset + length <= virtual_size);
- if (length == 0) {
+ if (length == 0 || !virtual_base || !impl) {
return;
}
impl->Protect(virtual_offset + virtual_base_offset, length, read, write);
diff --git a/src/common/host_memory.h b/src/common/host_memory.h
index eaa7d18ab5..9b8326d0fb 100644
--- a/src/common/host_memory.h
+++ b/src/common/host_memory.h
@@ -6,6 +6,7 @@
#include <memory>
#include "common/common_types.h"
+#include "common/virtual_buffer.h"
namespace Common {
@@ -61,6 +62,9 @@ private:
u8* backing_base{};
u8* virtual_base{};
size_t virtual_base_offset{};
+
+ // Fallback if fastmem is not supported on this platform
+ std::unique_ptr<Common::VirtualBuffer<u8>> fallback_buffer;
};
} // namespace Common