cpu-kvm: Move the validKvmEnvironment method into KvmVM.

This makes the generic System class consistent whether you have KVM
enabled or not.

Change-Id: Ie6928961200943d1d4e3bd129a4e4269e9f12950
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/56263
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/arm/kvm/gic.cc

@@ -188,7 +188,7 @@ void
 MuxingKvmGic::startup()
 {
     GicV2::startup();
-    usingKvm = (kernelGic != nullptr) && system.validKvmEnvironment();
+    usingKvm = kernelGic && vm && vm->validEnvironment();
     if (usingKvm)
         fromGicV2ToKvm();
 }
@@ -205,7 +205,7 @@ void
 MuxingKvmGic::drainResume()
 {
     GicV2::drainResume();
-    bool use_kvm = (kernelGic != nullptr) && system.validKvmEnvironment();
+    bool use_kvm = kernelGic && vm && vm->validEnvironment();
     if (use_kvm != usingKvm) {
         // Should only occur due to CPU switches
         if (use_kvm) // from simulation to KVM emulation

src/cpu/kvm/SConsopts

@@ -79,3 +79,4 @@ else:
     warning("Can not enable KVM, host seems to lack KVM support")
 
 export_vars.append('USE_KVM')
+export_vars.append('KVM_ISA')

src/cpu/kvm/vm.cc

@@ -542,6 +542,17 @@ KvmVM::createDevice(uint32_t type, uint32_t flags)
 #endif
 }
 
+bool
+KvmVM::validEnvironment() const
+{
+    for (auto *tc: system->threads) {
+        if (!dynamic_cast<BaseKvmCPU *>(tc->getCpuPtr()))
+            return false;
+    }
+
+    return true;
+}
+
 void
 KvmVM::setSystem(System *s)
 {

src/cpu/kvm/vm.hh

@@ -416,6 +416,9 @@ class KvmVM : public SimObject
     /** Global KVM interface */
     Kvm *kvm;
 
+    /** Verify gem5 configuration will support KVM emulation */
+    bool validEnvironment() const;
+
     /**
      * Initialize system pointer. Invoked by system object.
      */

src/dev/arm/generic_timer.cc

@@ -38,13 +38,17 @@
 #include "dev/arm/generic_timer.hh"
 
 #include <cmath>
+#include <string_view>
 
 #include "arch/arm/page_size.hh"
 #include "arch/arm/system.hh"
 #include "arch/arm/utility.hh"
 #include "base/logging.hh"
 #include "base/trace.hh"
+#include "config/kvm_isa.hh"
+#include "config/use_kvm.hh"
 #include "cpu/base.hh"
+#include "cpu/kvm/vm.hh"
 #include "debug/Timer.hh"
 #include "dev/arm/base_gic.hh"
 #include "mem/packet_access.hh"
@@ -403,6 +407,18 @@ ArchTimer::drainResume()
     updateCounter();
 }
 
+bool
+ArchTimerKvm::scheduleEvents()
+{
+    if constexpr (USE_KVM &&
+            std::string_view(KVM_ISA) == std::string_view("arm")) {
+        auto *vm = system.getKvmVM();
+        return !vm || !vm->validEnvironment();
+    } else {
+        return true;
+    }
+}
+
 GenericTimer::GenericTimer(const GenericTimerParams &p)
     : SimObject(p),
       systemCounter(*p.counter),

src/dev/arm/generic_timer.hh

@@ -280,9 +280,7 @@ class ArchTimerKvm : public ArchTimer
     // For ArchTimer's in a GenericTimerISA with Kvm execution about
     // to begin, skip rescheduling the event.
     // Otherwise, we should reschedule the event (if necessary).
-    bool scheduleEvents() override {
-        return !system.validKvmEnvironment();
-    }
+    bool scheduleEvents() override;
 };
 
 class GenericTimer : public SimObject

src/sim/system.cc

@@ -52,7 +52,6 @@
 #include "config/the_isa.hh"
 #include "config/use_kvm.hh"
 #if USE_KVM
-#include "cpu/kvm/base.hh"
 #include "cpu/kvm/vm.hh"
 #endif
 #if !IS_NULL_ISA
@@ -316,24 +315,6 @@ System::replaceThreadContext(ThreadContext *tc, ContextID context_id)
     }
 }
 
-bool
-System::validKvmEnvironment() const
-{
-#if USE_KVM
-    if (threads.empty())
-        return false;
-
-    for (auto *tc: threads) {
-        if (!dynamic_cast<BaseKvmCPU *>(tc->getCpuPtr()))
-            return false;
-    }
-
-    return true;
-#else
-    return false;
-#endif
-}
-
 Addr
 System::memSize() const
 {

src/sim/system.hh

@@ -336,9 +336,6 @@ class System : public SimObject, public PCEventScope
      */
     KvmVM *getKvmVM() { return kvmVM; }
 
-    /** Verify gem5 configuration will support KVM emulation */
-    bool validKvmEnvironment() const;
-
     /** Get a pointer to access the physical memory of the system */
     memory::PhysicalMemory& getPhysMem() { return physmem; }
     const memory::PhysicalMemory& getPhysMem() const { return physmem; }