virt-dt: Allow reservation of secure region when in a RAM carveout

In this case the secure code lives in RAM, and hence the memory node in
the device tree needs to be adjusted. This avoids that the OS will map
and possibly access the reservation.

Add support for setting CONFIG_ARMV7_SECURE_RESERVE_SIZE to carve out
such a region. We only support cutting off memory from the beginning or
the end of a RAM bank as we do not want to increase their number (which
would happen if punching a hole) for simplicity reasons

This will be used in a subsequent patch for Jetson-TK1.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

3 files changed, 36 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/virt-dt.c b/arch/arm/cpu/armv7/virt-dt.c
index caaaaab..32c368f 100644
--- a/arch/arm/cpu/armv7/virt-dt.c
+++ b/arch/arm/cpu/armv7/virt-dt.c
@@ -16,6 +16,7 @@
  */
 
 #include <common.h>
+#include <errno.h>
 #include <stdio_dev.h>
 #include <linux/ctype.h>
 #include <linux/types.h>
@@ -88,6 +89,34 @@ static int fdt_psci(void *fdt)
 	return 0;
 }
 
+int armv7_apply_memory_carveout(u64 *start, u64 *size)
+{
+#ifdef CONFIG_ARMV7_SECURE_RESERVE_SIZE
+	if (*start + *size < CONFIG_ARMV7_SECURE_BASE ||
+	    *start >= (u64)CONFIG_ARMV7_SECURE_BASE +
+		      CONFIG_ARMV7_SECURE_RESERVE_SIZE)
+		return 0;
+
+	/* carveout must be at the beginning or the end of the bank */
+	if (*start == CONFIG_ARMV7_SECURE_BASE ||
+	    *start + *size == (u64)CONFIG_ARMV7_SECURE_BASE +
+			      CONFIG_ARMV7_SECURE_RESERVE_SIZE) {
+		if (*size < CONFIG_ARMV7_SECURE_RESERVE_SIZE) {
+			debug("Secure monitor larger than RAM bank!?\n");
+			return -EINVAL;
+		}
+		*size -= CONFIG_ARMV7_SECURE_RESERVE_SIZE;
+		if (*start == CONFIG_ARMV7_SECURE_BASE)
+			*start += CONFIG_ARMV7_SECURE_RESERVE_SIZE;
+		return 0;
+	}
+	debug("Secure monitor not located at beginning or end of RAM bank\n");
+	return -EINVAL;
+#else /* !CONFIG_ARMV7_SECURE_RESERVE_SIZE */
+	return 0;
+#endif
+}
+
 int psci_update_dt(void *fdt)
 {
 #ifdef CONFIG_ARMV7_NONSEC
diff --git a/arch/arm/include/asm/armv7.h b/arch/arm/include/asm/armv7.h
index 33af885..30e7939 100644
--- a/arch/arm/include/asm/armv7.h
+++ b/arch/arm/include/asm/armv7.h
@@ -134,6 +134,7 @@ void v7_outer_cache_inval_range(u32 start, u32 end);
 #ifdef CONFIG_ARMV7_NONSEC
 
 int armv7_init_nonsec(void);
+int armv7_apply_memory_carveout(u64 *start, u64 *size);
 bool armv7_boot_nonsec(void);
 
 /* defined in assembly file */
diff --git a/arch/arm/lib/bootm-fdt.c b/arch/arm/lib/bootm-fdt.c
index 49ba691..0eb10a8 100644
--- a/arch/arm/lib/bootm-fdt.c
+++ b/arch/arm/lib/bootm-fdt.c
@@ -17,6 +17,7 @@
 
 #include <common.h>
 #include <fdt_support.h>
+#include <asm/armv7.h>
 #include <asm/psci.h>
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -31,6 +32,11 @@ int arch_fixup_fdt(void *blob)
 	for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; bank++) {
 		start[bank] = bd->bi_dram[bank].start;
 		size[bank] = bd->bi_dram[bank].size;
+#ifdef CONFIG_ARMV7_NONSEC
+		ret = armv7_apply_memory_carveout(&start[bank], &size[bank]);
+		if (ret)
+			return ret;
+#endif
 	}
 
 	ret = fdt_fixup_memory_banks(blob, start, size, CONFIG_NR_DRAM_BANKS);