Support CoVE local attestation by reserving memory in the kernel imag…

…e for TVM Attestation Payload (TAP). Pass the physical address of the TAP when requesting to be promoted to a TVM. Signed-off-by: Wojciech Ozga <woz@zurich.ibm.com>
rivosinc · Oct 7, 2024 · 998239d · 998239d
1 parent c1fffab
commit 998239d
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Showing 4 changed files with 28 additions and 1 deletion.
diff --git a/arch/riscv/cove/core.c b/arch/riscv/cove/core.c
@@ -14,6 +14,8 @@
 #include <asm/cove.h>
 #include <linux/mm.h>
 
+extern char __cove_tap_start[];
+
 static bool is_tvm;
 
 bool is_cove_guest(void)
@@ -47,7 +49,7 @@ int promote_to_cove_guest()
 
 	if (strstr(boot_command_line, "promote_to_cove_guest")) {
 		ret = sbi_ecall(SBI_EXT_COVH, SBI_EXT_COVH_PROMOTE_TO_TVM, dtb_early_pa,
-				0, 0, 0, 0, 0);
+				__pa(__cove_tap_start), 0, 0, 0, 0);
 		if (ret.error) {
 				rc = sbi_err_map_linux_errno(ret.error);
 				goto done;

diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S b/arch/riscv/kernel/vmlinux-xip.lds.S
@@ -58,6 +58,17 @@ SECTIONS
 	}
 	_exiprom = .;			/* End of XIP ROM area */
 
+#ifdef CONFIG_RISCV_COVE_GUEST
+	. = ALIGN(4096);
+	.cove_tvm_attestation_payload : {
+		__cove_tap_start =  .;
+		LONG(0xace0ace0)
+		SHORT(0x0FFA)
+		FILL(0x00)
+       . += 4090;
+		__cove_tap_end =  .;
+	}
+#endif
 
 /*
  * From this point, stuff is considered writable and will be copied to RAM

diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
@@ -113,6 +113,18 @@ SECTIONS
 	}
 	__init_end = .;
 
+#ifdef CONFIG_RISCV_COVE_GUEST
+	. = ALIGN(4096);
+	.cove_tvm_attestation_payload : {
+		__cove_tap_start =  .;
+		LONG(0xace0ace0)
+		SHORT(0x0FFA)
+		FILL(0x00)
+       . += 4090;
+		__cove_tap_end =  .;
+	}
+#endif
+
 	/* Start of data section */
 	_sdata = .;
 	RO_DATA(SECTION_ALIGN)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
@@ -1167,6 +1167,7 @@ int __init early_init_dt_scan_chosen(char *cmdline)
 	early_init_dt_check_for_initrd(node);
 	early_init_dt_check_for_elfcorehdr(node);
 
+#ifndef CONFIG_RISCV_COVE_GUEST
 	rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
 	if (rng_seed && l > 0) {
 		add_bootloader_randomness(rng_seed, l);
@@ -1178,6 +1179,7 @@ int __init early_init_dt_scan_chosen(char *cmdline)
 		of_fdt_crc32 = crc32_be(~0, initial_boot_params,
 				fdt_totalsize(initial_boot_params));
 	}
+#endif
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);