[PATCH 11/22] platform: generic: mips p8700: restrict memory region to physical memory as in DTS

[Vladimir Kondratiev]

SBI domain initialization add "all memory" region with unrestricted
access. This can cause a problem: CPU can issue
speculative prefetches to non-existent addresses. If this access
goes to the system NOC, it is mis-interpreted as an access violation
and error is reported, forcing system reset.

To prevent such a speculative transaction to leave a CPU cluster,
block it using PMP, by restricting memory region to physically present
memory.

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev at mobileye.com>
---
 platform/generic/mips/p8700.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/platform/generic/mips/p8700.c b/platform/generic/mips/p8700.c
index 25e6075581e8..a3d05602a6d1 100644
--- a/platform/generic/mips/p8700.c
+++ b/platform/generic/mips/p8700.c
@@ -14,6 +14,7 @@
 #include <sbi/sbi_timer.h>
 #include <sbi/sbi_hart_pmp.h>
 #include <sbi/riscv_io.h>
+#include <libfdt.h>
 #include <sbi_utils/fdt/fdt_helper.h>
 #include <mips/p8700.h>
 #include <mips/mips-cm.h>
@@ -148,14 +149,36 @@ static struct sbi_domain_memregion *find_last_memregion(const struct sbi_domain
 	return --reg;
 }
 
+static int fixup_dram_region(const struct sbi_domain *dom,
+			     struct sbi_domain_memregion *reg)
+{
+	const void *fdt = fdt_get_address();
+	int node;
+	int ret;
+	uint64_t mem_addr, mem_size;
+	static const char mem_str[] = "memory";
+
+	if (!reg || !fdt)
+		return SBI_EINVAL;
+
+	/* Find the memory range */
+	node = fdt_node_offset_by_prop_value(fdt, -1, "device_type",
+					     mem_str, sizeof(mem_str));
+	ret = fdt_get_node_addr_size(fdt, node, 0, &mem_addr, &mem_size);
+	if (ret)
+		return ret;
+	sbi_domain_memregion_init(mem_addr, mem_size, reg->flags, reg);
+	return 0;
+}
+
 static int mips_p8700_final_init(bool cold_boot)
 {
 	struct sbi_scratch *scratch;
 	const struct sbi_domain *dom;
 	struct sbi_domain_memregion *reg;
-	const unsigned long end_of_dram = 0x1000000000LU;
 	unsigned long pmp_gran;
 	int pmp_count;
+	int ret;
 
 	if (!cold_boot)
 		return 0;
@@ -172,11 +195,9 @@ static int mips_p8700_final_init(bool cold_boot)
 	 */
 	dom = sbi_domain_thishart_ptr();
 	reg = find_last_memregion(dom);
-	sbi_printf("Fix region[%ld]: base 0x%lx order %ld flags 0x%lx\n",
-		   reg - dom->regions, reg->base, reg->order, reg->flags);
-	reg->order = sbi_fls(end_of_dram);
-	sbi_printf("Modified order: %ld to match end of DRAM 0x%lx\n",
-		   reg->order, end_of_dram);
+	ret = fixup_dram_region(dom, reg);
+	if (ret)
+		return ret;
 	/*
 	 * clear the rest of regions that may be set by the boot code
 	 * SBI code don't let to disable PMP region, so configure it to
-- 
2.43.0