acpi: introduce WDAT table for GWDT
Add build_gwdt_wdat() to generate a Watchdog Action Table designed for SBSA Generic Watchdog Timer. Signed-off-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Message-ID: <20260702145856.1539572-7-imammedo@redhat.com>
Igor Mammedov committed
Jul 2, 2026 at 16:58 UTC
beadd272c10289c0086d66fc5d1a0c5229127916
4 files changed
+136
hw/acpi/meson.build
+2
@@ -31,11 +31,13 @@ acpi_ss.add(when: 'CONFIG_ACPI_ERST', if_true: files('erst.c'))
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acpi_ss.add(when: 'CONFIG_IPMI', if_true: files('ipmi.c'))
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stub_ss.add(files('ipmi-stub.c'))
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stub_ss.add(files('acpi-x86-stub.c'))
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+acpi_ss.add(when: 'CONFIG_WDT_SBSA', if_true: files('wdat-gwdt.c'))
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if have_tpm
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acpi_ss.add(files('tpm.c'))
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endif
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stub_ss.add(files('acpi-stub.c', 'aml-build-stub.c', 'ghes-stub.c'))
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stub_ss.add(files('pci-bridge-stub.c'))
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+stub_ss.add(files('wdat-gwdt-stub.c'))
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system_ss.add_all(when: 'CONFIG_ACPI', if_true: acpi_ss)
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system_ss.add(when: 'CONFIG_GHES_CPER', if_true: files('ghes_cper.c'))
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stub_ss.add(files('ghes_cper_stub.c'))
hw/acpi/wdat-gwdt-stub.c
new
+16
@@ -0,0 +1,16 @@
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+/*
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+ * Copyright Red Hat, Inc. 2026
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+ * Author(s): Igor Mammedov <imammedo@redhat.com>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ */
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+
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+#include "qemu/osdep.h"
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+#include "hw/acpi/wdat-gwdt.h"
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+
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+void build_gwdt_wdat(GArray *table_data, BIOSLinker *linker, const char *oem_id,
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+ const char *oem_table_id, uint64_t rbase, uint64_t cbase,
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+ uint64_t freq)
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+{
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+ g_assert_not_reached();
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+}
hw/acpi/wdat-gwdt.c
new
+99
@@ -0,0 +1,99 @@
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+/*
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+ * SBSA GWDT Watchdog Action Table (WDAT)
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+ *
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+ * Copyright Red Hat, Inc. 2026
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+ * Author(s): Igor Mammedov <imammedo@redhat.com>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ */
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+
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+#include "qemu/osdep.h"
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+#include "hw/acpi/aml-build.h"
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+#include "hw/acpi/wdat-gwdt.h"
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+#include "hw/acpi/wdat.h"
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+#include "hw/watchdog/sbsa_gwdt.h"
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+
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+#define GWDT_REG(base, reg_offset, reg_width) { \
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+ .space_id = AML_AS_SYSTEM_MEMORY, \
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+ .address = base + reg_offset, .bit_width = reg_width, \
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+ .access_width = AML_DWORD_ACC };
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+
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+/*
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+ * "Hardware Watchdog Timers Design Specification"
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+ * https://uefi.org/acpi 'Watchdog Action Table (WDAT)'
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+ */
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+void build_gwdt_wdat(GArray *table_data, BIOSLinker *linker, const char *oem_id,
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+ const char *oem_table_id, uint64_t rbase, uint64_t cbase,
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+ uint64_t freq)
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+{
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+ AcpiTable table = { .sig = "WDAT", .rev = 1, .oem_id = oem_id,
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+ .oem_table_id = oem_table_id };
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+
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+ struct AcpiGenericAddress wrr = GWDT_REG(rbase, 0x0, 32);
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+ struct AcpiGenericAddress wor_l = GWDT_REG(cbase, SBSA_GWDT_WOR, 32);
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+ struct AcpiGenericAddress wcs = GWDT_REG(cbase, SBSA_GWDT_WCS, 32);
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+
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+ acpi_table_begin(&table, table_data);
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+ build_append_int_noprefix(table_data, 0x20, 4); /* Watchdog Header Length */
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+ /*
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+ * PCI location fields are set to 0xff to indicate
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+ * that the watchdog is not a PCI device.
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+ */
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+ build_append_int_noprefix(table_data, 0xff, 2); /* PCI Segment */
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+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Bus Number */
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+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Device Number */
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+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Function Number */
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+ build_append_int_noprefix(table_data, 0, 3); /* Reserved */
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+ /*
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+ * WDAT spec: "The clock interval that the WDT uses must be
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+ * greater than or equal to 1 millisecond."
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+ */
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+ g_assert(freq <= 1000);
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+ /* Timer Period, ms */
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+ build_append_int_noprefix(table_data, 1000 / freq, 4);
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+ /*
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+ * WDAT spec: "The time-out period before the WDT fires is recommended
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+ * to be at least 5 minutes."
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+ * Set max count to 10min and min count to 5sec.
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+ */
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+ build_append_int_noprefix(table_data, 600 * freq, 4); /* Maximum Count */
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+ build_append_int_noprefix(table_data, 5 * freq, 4); /* Minimum Count */
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+ /*
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+ * WATCHDOG_ENABLED | WATCHDOG_STOPPED_IN_SLEEP_STATE
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+ */
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+ build_append_int_noprefix(table_data, 0x81, 1); /* Watchdog Flags */
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+ build_append_int_noprefix(table_data, 0, 3); /* Reserved */
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+ /*
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+ * watchdog instruction entries
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+ */
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+ build_append_int_noprefix(table_data, 8, 4);
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+ /* Action table: WCS (control/status) register actions */
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_RUNNING_STATE,
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+ WDAT_INS_READ_VALUE,
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+ wcs, 0x1, 0x1);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_RUNNING_STATE,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ wcs, 1, 0x00000001);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_STOPPED_STATE,
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+ WDAT_INS_READ_VALUE,
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+ wcs, 0x0, 0x00000001);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_STOPPED_STATE,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ wcs, 0x0, 0x00000001);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_WATCHDOG_STATUS,
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+ WDAT_INS_READ_VALUE,
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+ wcs, 0x4, 0x00000004);
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+ /* WOR (offset) and WRR (refresh) register actions */
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_COUNTDOWN_PERIOD,
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+ WDAT_INS_WRITE_COUNTDOWN,
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+ wor_l, 0, 0xffffffff);
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+ /* WRR: any write refreshes the watchdog, value is ignored */
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+ build_append_wdat_ins(table_data, WDAT_ACTION_RESET,
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+ WDAT_INS_WRITE_VALUE,
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+ wrr, 0x1, 0x1);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_WATCHDOG_STATUS,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ wrr, 0x4, 0x4);
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+
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+ acpi_table_end(linker, &table);
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+}
include/hw/acpi/wdat-gwdt.h
new
+19
@@ -0,0 +1,19 @@
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+/*
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+ * GWDT Watchdog Action Table (WDAT) definition
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+ *
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+ * Copyright Red Hat, Inc. 2026
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+ * Author(s): Igor Mammedov <imammedo@redhat.com>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ */
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+#ifndef QEMU_HW_ACPI_WDAT_GWDT_H
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+#define QEMU_HW_ACPI_WDAT_GWDT_H
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+
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+#include "hw/acpi/aml-build.h"
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+#include "hw/watchdog/sbsa_gwdt.h"
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+
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+void build_gwdt_wdat(GArray *table_data, BIOSLinker *linker, const char *oem_id,
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+ const char *oem_table_id, uint64_t rbase, uint64_t cbase,
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+ uint64_t freq);
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+
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+#endif /* QEMU_HW_ACPI_WDAT_GWDT_H */