[PATCH v6 1/8] i386: Add Intel RDT device and State to config.

[Hendrik Wuethrich <whendrik@google.com>]

Change config to show RDT, add minimal code to the rdt.c module to make
sure things still compile.

Signed-off-by: Hendrik Wuethrich <whendrik@google.com>
---
 hw/i386/Kconfig       |  4 ++
 hw/i386/meson.build   |  1 +
 hw/i386/rdt.c         | 97 +++++++++++++++++++++++++++++++++++++++++++
 include/hw/i386/rdt.h | 35 ++++++++++++++++
 target/i386/cpu.h     |  4 ++
 5 files changed, 141 insertions(+)
 create mode 100644 hw/i386/rdt.c
 create mode 100644 include/hw/i386/rdt.h

diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
index d34ce07b21..a3a6b2259c 100644
--- a/hw/i386/Kconfig
+++ b/hw/i386/Kconfig
@@ -10,6 +10,9 @@ config SGX
     bool
     depends on KVM
 
+config RDT
+    bool
+
 config PC
     bool
     imply APPLESMC
@@ -26,6 +29,7 @@ config PC
     imply QXL
     imply SEV
     imply SGX
+    imply RDT
     imply TEST_DEVICES
     imply TPM_CRB
     imply TPM_TIS_ISA
diff --git a/hw/i386/meson.build b/hw/i386/meson.build
index 10bdfde27c..3a697dcc03 100644
--- a/hw/i386/meson.build
+++ b/hw/i386/meson.build
@@ -22,6 +22,7 @@ i386_ss.add(when: 'CONFIG_VMPORT', if_true: files('vmport.c'))
 i386_ss.add(when: 'CONFIG_VTD', if_true: files('intel_iommu.c'))
 i386_ss.add(when: 'CONFIG_SGX', if_true: files('sgx-epc.c','sgx.c'),
                                 if_false: files('sgx-stub.c'))
+i386_ss.add(when: 'CONFIG_RDT', if_true: files('rdt.c'))
 
 i386_ss.add(when: 'CONFIG_ACPI', if_true: files('acpi-common.c'))
 i386_ss.add(when: 'CONFIG_PC', if_true: files(
diff --git a/hw/i386/rdt.c b/hw/i386/rdt.c
new file mode 100644
index 0000000000..76a253902b
--- /dev/null
+++ b/hw/i386/rdt.c
@@ -0,0 +1,97 @@
+/*
+ * Intel Resource Director Technology (RDT).
+ *
+ * Copyright 2025 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#include "hw/i386/rdt.h"
+#include "qemu/osdep.h" /* Needs to be included before isa.h */
+#include "hw/isa/isa.h"
+#include "hw/qdev-properties.h"
+#include "qom/object.h"
+
+#define TYPE_RDT "rdt"
+#define RDT_NUM_RMID_PROP "rmids"
+
+OBJECT_DECLARE_TYPE(RDTState, RDTStateClass, RDT);
+
+struct RDTMonitor {
+    uint64_t count_local;
+    uint64_t count_remote;
+    uint64_t count_l3;
+};
+
+struct RDTAllocation {
+    QemuMutex lock;
+    uint32_t active_cos;
+};
+
+struct RDTStatePerCore {
+    QemuMutex lock;
+    uint32_t active_rmid;
+};
+
+struct RDTStatePerL3Cache {
+    QemuMutex lock;
+
+    RDTMonitor *monitors;
+
+    /* RDT Allocation bitmask MSRs */
+    uint32_t msr_L3_ia32_mask_n[RDT_MAX_L3_MASK_COUNT];
+    uint32_t msr_L2_ia32_mask_n[RDT_MAX_L2_MASK_COUNT];
+    uint32_t ia32_L2_qos_ext_bw_thrtl_n[RDT_MAX_MBA_THRTL_COUNT];
+
+    /* Parent RDTState */
+    RDTState *rdtstate;
+};
+
+/* One instance of RDT-internal state to be shared by all cores */
+struct RDTState {
+    ISADevice parent;
+
+    /* Max amount of RMIDs */
+    uint32_t rmids;
+
+    uint16_t l3_caches;
+
+    RDTStatePerL3Cache *rdtInstances;
+    RDTAllocation *allocations;
+};
+
+struct RDTStateClass {
+};
+
+OBJECT_DEFINE_TYPE(RDTState, rdt, RDT, ISA_DEVICE);
+
+static Property rdt_properties[] = {
+    DEFINE_PROP_UINT32(RDT_NUM_RMID_PROP, RDTState, rmids, 256),
+};
+
+static void rdt_init(Object *obj)
+{
+}
+
+static void rdt_finalize(Object *obj)
+{
+}
+
+static void rdt_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->hotpluggable = false;
+    dc->desc = "RDT";
+    dc->user_creatable = true;
+
+    device_class_set_props(dc, rdt_properties);
+}
diff --git a/include/hw/i386/rdt.h b/include/hw/i386/rdt.h
new file mode 100644
index 0000000000..1f99f98f7f
--- /dev/null
+++ b/include/hw/i386/rdt.h
@@ -0,0 +1,35 @@
+/*
+ * Intel Resource Director Technology (RDT).
+ *
+ * Copyright 2025 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#ifndef HW_RDT_H
+#define HW_RDT_H
+
+/* Max counts for allocation masks or CBMs. In other words, the size of
+ * respective MSRs.
+ * L3_MASK and L3_mask are architectural limitations. THRTL_COUNT is just
+ * the space left until the next MSR.
+ * */
+#define RDT_MAX_L3_MASK_COUNT      127
+#define RDT_MAX_L2_MASK_COUNT      63
+#define RDT_MAX_MBA_THRTL_COUNT    63
+
+typedef struct RDTState RDTState;
+typedef struct RDTStatePerL3Cache RDTStatePerL3Cache;
+typedef struct RDTStatePerCore RDTStatePerCore;
+typedef struct RDTMonitor RDTMonitor;
+typedef struct RDTAllocation RDTAllocation;
+
+#endif
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index c67b42d34f..2cbcc8fe4e 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2253,6 +2253,10 @@ struct ArchCPU {
     struct MemoryRegion *cpu_as_root, *cpu_as_mem, *smram;
     Notifier machine_done;
 
+    /* Help the RDT MSRs find the RDT device state */
+    struct RDTStatePerL3Cache *rdtStatePerL3Cache;
+    struct RDTStatePerCore *rdtPerCore;
+
     struct kvm_msrs *kvm_msr_buf;
 
     int32_t node_id; /* NUMA node this CPU belongs to */
-- 
2.48.1.711.g2feabab25a-goog