Support CoVE local attestation by reserving memory in the kernel image 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>

Author: wojciechozga

arch/riscv/kernel/head.S

@@ -205,6 +205,7 @@ ENTRY(_start_kernel)
 	li a7, 0x434F5648        /* SBI_EXT_COVH */
 	li a6, 0x15              /* SBI_EXT_COVH_PROMOTE_TO_TVM */
 	mv a0, a1                /* DTB physical address */
+	la a1, __cove_tap_start	 /* TAP physical address */
 	ecall
 	/* Attestation reflects the result of promotion, so ignore it */
 	mv a0, s0

arch/riscv/kernel/vmlinux-xip.lds.S

@@ -106,6 +106,18 @@ 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
+
 	. = ALIGN(16);
 	.xip.traps : {
 		__xip_traps_start = .;

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)

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);