[kvm-unit-tests PATCH v2 4/8] riscv: Add ACPI support for ISA string discovery

[Xiang W]

When a DT is not provided, walk the RHCT Hart Info nodes and parse
the referenced ISA String node instead of aborting in isa_init()
and cpu_has_extension_name().

Match the current hart by ACPI UID (DT still matches by hartid)
and feed the ISA string into the existing isa_parse() helper so
extension detection is shared by both firmware descriptions.

Rename isa_info.hartid to isa_info.id so the same iterator state
can hold either identifier.

Signed-off-by: Xiang W <wangxiang at iscas.ac.cn>
---
 lib/acpi.h      | 28 +++++++++++++++++
 lib/riscv/isa.c | 81 ++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 102 insertions(+), 7 deletions(-)

diff --git a/lib/acpi.h b/lib/acpi.h
index 0589669b..d5e238a9 100644
--- a/lib/acpi.h
+++ b/lib/acpi.h
@@ -334,6 +334,34 @@ struct acpi_table_rhct {
 	u32 node_offset;
 };
 
+#define ACPI_RHCT_NODE_HEADER_DEF \
+	u16 type;	\
+	u16 length;	\
+	u16 revision;	\
+
+struct acpi_rhct_node {
+	ACPI_RHCT_NODE_HEADER_DEF
+	char data[];
+};
+
+enum acpi_rhct_node_type {
+	ACPI_RHCT_NODE_TYPE_ISA_STRING = 0x0,
+	ACPI_RHCT_NODE_TYPE_HART_INFO = 0xFFFF
+};
+
+struct acpi_rhct_node_isa_string {
+	ACPI_RHCT_NODE_HEADER_DEF
+	u16 isa_length;
+	char isa[];
+};
+
+struct acpi_rhct_node_hart_info {
+	ACPI_RHCT_NODE_HEADER_DEF
+	u16 num_offsets;
+	u32 uid;
+	u32 nodes[];
+};
+
 /* Reset to default packing */
 #pragma pack()
 
diff --git a/lib/riscv/isa.c b/lib/riscv/isa.c
index bc1c9c72..91c7302c 100644
--- a/lib/riscv/isa.c
+++ b/lib/riscv/isa.c
@@ -12,7 +12,7 @@
 typedef void (*isa_func_t)(const char *, int, void *);
 
 struct isa_info {
-	unsigned long hartid;
+	unsigned long id;
 	isa_func_t func;
 	void *data;
 };
@@ -74,7 +74,7 @@ static void isa_parse_fdt(int cpu_node, u64 hartid, void *data)
 	const struct fdt_property *prop;
 	int len;
 
-	if (hartid != info->hartid)
+	if (hartid != info->id)
 		return;
 
 	prop = fdt_get_property(dt_fdt(), cpu_node, "riscv,isa", &len);
@@ -83,32 +83,92 @@ static void isa_parse_fdt(int cpu_node, u64 hartid, void *data)
 	isa_parse(prop->data, len, info);
 }
 
-static void isa_init_acpi(void)
+#ifdef CONFIG_EFI
+#include <acpi.h>
+
+static void isa_parse_acpi(struct acpi_table_rhct *rhct,
+			   struct acpi_rhct_node_hart_info *hart_info, void *data)
 {
-	assert_msg(false, "ACPI not available");
+	u32 offset;
+	struct acpi_rhct_node *node;
+	struct acpi_rhct_node_isa_string *isa_string;
+	struct isa_info *info = (struct isa_info *)data;
+
+	if (hart_info->uid != info->id)
+		return;
+
+	for (int i = 0; i < hart_info->num_offsets; i++) {
+		offset = hart_info->nodes[i];
+		if (offset >= rhct->length)
+			break;
+		node = (void *)rhct + offset;
+		if (node->type == ACPI_RHCT_NODE_TYPE_ISA_STRING) {
+			isa_string = (void *) node;
+			isa_parse(isa_string->isa, isa_string->isa_length, info);
+		}
+	}
+}
+
+static int acpi_rhct_for_each_hart(void (*func)(struct acpi_table_rhct *,
+						 struct acpi_rhct_node_hart_info *,
+						 void *), void *data)
+{
+	u32 offset;
+	struct acpi_table_rhct *rhct;
+	struct acpi_rhct_node *node;
+	struct acpi_rhct_node_hart_info *hart_info;
+
+	rhct = find_acpi_table_addr(RHCT_SIGNATURE);
+	if (rhct == NULL)
+		return -1;
+
+	offset = rhct->node_offset;
+	for (int i = 0; i < rhct->node_count; i++) {
+		if (offset >= rhct->length)
+			return -1;
+
+		node = (void *)rhct + offset;
+		if (node->length < sizeof(*node))
+			return -1;
+
+		if (node->type == ACPI_RHCT_NODE_TYPE_HART_INFO) {
+			hart_info = (void *)node;
+			func(rhct, hart_info, data);
+		}
+
+		offset += node->length;
+	}
+
+	return 0;
 }
+#endif
 
 void isa_init(struct thread_info *ti)
 {
 	struct isa_info info = {
-		.hartid = ti->hartid,
 		.func = isa_bit,
 		.data = ti,
 	};
 	int ret;
 
 	if (dt_available()) {
+		info.id = ti->hartid;
 		ret = dt_for_each_cpu_node(isa_parse_fdt, &info);
 		assert(ret == 0);
 	} else {
-		isa_init_acpi();
+#ifdef CONFIG_EFI
+		info.id = ti->uid;
+		ret = acpi_rhct_for_each_hart(isa_parse_acpi, &info);
+		assert(ret == 0);
+#else
+		assert_msg(false, "ACPI not available");
+#endif
 	}
 }
 
 bool cpu_has_extension_name(int cpu, const char *ext)
 {
 	struct isa_info info = {
-		.hartid = cpus[cpu].hartid,
 		.func = isa_name,
 		.data = &(struct isa_check){ .ext = ext, },
 	};
@@ -116,10 +176,17 @@ bool cpu_has_extension_name(int cpu, const char *ext)
 	int ret;
 
 	if (dt_available()) {
+		info.id = cpus[cpu].hartid;
 		ret = dt_for_each_cpu_node(isa_parse_fdt, &info);
 		assert(ret == 0);
 	} else {
+#ifdef CONFIG_EFI
+		info.id = cpus[cpu].uid;
+		ret = acpi_rhct_for_each_hart(isa_parse_acpi, &info);
+		assert(ret == 0);
+#else
 		assert_msg(false, "ACPI not available");
+#endif
 	}
 
 	return check->found;
-- 
2.47.3