[kvm-unit-tests PATCH 1/7] riscv: Initialize the ACPI RSDP from the EFI system table

[Xiang W]

On EFI boots without a DT, ACPI table lookup needs a valid RSDP.
Fetch the ACPI 2.0 table from the EFI configuration table and
register it with set_efi_rsdp() before cpu_init() and
timer_get_frequency().

The RSDP lives in EFI_ACPI_RECLAIM_MEMORY, which the RISC-V
allocator does not reuse, so there is no need to copy it aside.

Signed-off-by: Xiang W <wangxiang at iscas.ac.cn>
---
 lib/riscv/setup.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/lib/riscv/setup.c b/lib/riscv/setup.c
index a30aa0c4..8c22120d 100644
--- a/lib/riscv/setup.c
+++ b/lib/riscv/setup.c
@@ -226,10 +226,31 @@ void setup(const void *fdt, phys_addr_t freemem_start)
 
 #ifdef CONFIG_EFI
 #include <efi.h>
+#include <acpi.h>
 
 extern unsigned long exception_vectors;
 extern unsigned long boot_hartid;
 
+static efi_status_t setup_rsdp(efi_bootinfo_t *efi_bootinfo __unused)
+{
+	efi_status_t status;
+	struct acpi_table_rsdp *rsdp;
+
+	/*
+	 * RSDP resides in an EFI_ACPI_RECLAIM_MEMORY region, which is not used
+	 * by kvm-unit-tests RISC-V memory allocator. So it is not necessary to
+	 * copy the data structure to another memory region to prevent
+	 * unintentional overwrite.
+	 */
+	status = efi_get_system_config_table(ACPI_20_TABLE_GUID, (void **)&rsdp);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	set_efi_rsdp(rsdp);
+
+	return EFI_SUCCESS;
+}
+
 static efi_status_t efi_mem_init(efi_bootinfo_t *efi_bootinfo)
 {
 	struct mem_region *freemem_mr = NULL, *code, *data;
@@ -273,6 +294,14 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
 		return status;
 	}
 
+	if (!dt_available()) {
+		status = setup_rsdp(efi_bootinfo);
+		if (status != EFI_SUCCESS) {
+			printf("Cannot find RSDP in EFI system table\n");
+			return status;
+		}
+	}
+
 	cpu_init();
 	timer_get_frequency();
 	thread_info_init();
-- 
2.47.3