Added RandomX option "rdmsr" and save/restore MSR registers on Windows.

src/config.json

@@ -17,6 +17,7 @@
         "init": -1,
         "mode": "auto",
         "1gb-pages": false,
+        "rdmsr": true,
         "wrmsr": true,
         "numa": true
     },

src/crypto/rx/RxConfig.cpp

@@ -49,6 +49,7 @@ namespace xmrig {
 static const char *kInit        = "init";
 static const char *kMode        = "mode";
 static const char *kOneGbPages  = "1gb-pages";
+static const char *kRdmsr       = "rdmsr";
 static const char *kWrmsr       = "wrmsr";
 
 #ifdef XMRIG_FEATURE_HWLOC
@@ -82,6 +83,7 @@ bool xmrig::RxConfig::read(const rapidjson::Value &value)
     if (value.IsObject()) {
         m_threads    = Json::getInt(value, kInit, m_threads);
         m_mode       = readMode(Json::getValue(value, kMode));
+        m_rdmsr      = Json::getBool(value, kRdmsr, m_rdmsr);
 
 #       ifdef XMRIG_FEATURE_MSR
         readMSR(Json::getValue(value, kWrmsr));
@@ -129,6 +131,7 @@ rapidjson::Value xmrig::RxConfig::toJSON(rapidjson::Document &doc) const
     obj.AddMember(StringRef(kInit),         m_threads, allocator);
     obj.AddMember(StringRef(kMode),         StringRef(modeName()), allocator);
     obj.AddMember(StringRef(kOneGbPages),   m_oneGbPages, allocator);
+    obj.AddMember(StringRef(kRdmsr),        m_rdmsr, allocator);
 
 #   ifdef XMRIG_FEATURE_MSR
     if (!m_msrPreset.empty()) {

src/crypto/rx/RxConfig.h

@@ -63,6 +63,7 @@ public:
     uint32_t threads(uint32_t limit = 100) const;
 
     inline bool isOneGbPages() const    { return m_oneGbPages; }
+    inline bool rdmsr() const           { return m_rdmsr; }
     inline bool wrmsr() const           { return m_wrmsr; }
     inline Mode mode() const            { return m_mode; }
 
@@ -86,6 +87,7 @@ private:
 
     bool m_numa         = true;
     bool m_oneGbPages   = false;
+    bool m_rdmsr        = true;
     int m_threads       = -1;
     Mode m_mode         = AutoMode;
 

src/crypto/rx/Rx_windows.cpp

@@ -48,8 +48,9 @@
 namespace xmrig {
 
 
-static const char *tag  = YELLOW_BG_BOLD(WHITE_BOLD_S " msr ") " ";
 static bool reuseDriver = false;
+static const char *tag  = YELLOW_BG_BOLD(WHITE_BOLD_S " msr ") " ";
+static MsrItems savedState;
 
 
 static SC_HANDLE hManager;
@@ -177,10 +178,12 @@ static HANDLE wrmsr_install_driver()
 }
 
 
+#define IOCTL_READ_MSR  CTL_CODE(40000, 0x821, METHOD_BUFFERED, FILE_ANY_ACCESS)
 #define IOCTL_WRITE_MSR CTL_CODE(40000, 0x822, METHOD_BUFFERED, FILE_ANY_ACCESS)
 
 
-static bool wrmsr(HANDLE driver, uint32_t reg, uint64_t value) {
+static bool wrmsr(HANDLE driver, uint32_t reg, uint64_t value)
+{
     struct {
         uint32_t reg = 0;
         uint32_t value[2]{};
@@ -204,7 +207,32 @@ static bool wrmsr(HANDLE driver, uint32_t reg, uint64_t value) {
 }
 
 
-static bool wrmsr(const MsrItems &preset)
+static bool rdmsr(HANDLE driver, uint32_t reg, uint64_t &value)
+{
+    DWORD size = 0;
+
+    if (!DeviceIoControl(driver, IOCTL_READ_MSR, &reg, sizeof(reg), &value, sizeof(value), &size, nullptr)) {
+        LOG_WARN(CLEAR "%s" YELLOW_BOLD_S "cannot read MSR 0x%08" PRIx32, tag, reg);
+
+        return false;
+    }
+
+    return true;
+}
+
+
+static MsrItem rdmsr(HANDLE driver, uint32_t reg)
+{
+    uint64_t value = 0;
+    if (!rdmsr(driver, reg, value)) {
+        return {};
+    }
+
+    return { reg, value };
+}
+
+
+static bool wrmsr(const MsrItems &preset, bool save)
 {
     bool success = true;
 
@@ -219,6 +247,15 @@ static bool wrmsr(const MsrItems &preset)
         return false;
     }
 
+    if (save) {
+        for (const auto &i : preset) {
+            auto item = rdmsr(driver, i.reg());
+            if (item.isValid()) {
+                savedState.emplace_back(item);
+            }
+        }
+    }
+
     std::thread wrmsr_thread([driver, &preset, &success]() {
         for (uint32_t i = 0, n = Cpu::info()->threads(); i < n; ++i) {
             if (!Platform::setThreadAffinity(i)) {
@@ -258,7 +295,7 @@ void xmrig::Rx::msrInit(const RxConfig &config)
 
     const uint64_t ts = Chrono::steadyMSecs();
 
-    if (wrmsr(preset)) {
+    if (wrmsr(preset, config.rdmsr())) {
         LOG_NOTICE(CLEAR "%s" GREEN_BOLD_S "register values for \"%s\" preset has been set successfully" BLACK_BOLD(" (%" PRIu64 " ms)"), tag, config.msrPresetName(), Chrono::steadyMSecs() - ts);
     }
 }
@@ -266,4 +303,13 @@ void xmrig::Rx::msrInit(const RxConfig &config)
 
 void xmrig::Rx::msrDestroy()
 {
+    if (savedState.empty()) {
+        return;
+    }
+
+    const uint64_t ts = Chrono::steadyMSecs();
+
+    if (!wrmsr(savedState, false)) {
+        LOG_ERR(CLEAR "%s" RED_BOLD_S "failed to restore initial state" BLACK_BOLD(" (%" PRIu64 " ms)"), tag, Chrono::steadyMSecs() - ts);
+    }
 }