Re: [PATCH v3 3/3] hw/riscv: Add the checking if DTB overlaps to kernel or initrd

[Daniel Henrique Barboza]

On 11/8/24 4:04 AM, Jim Shu wrote:

DTB is placed to the end of memory, so we will check if the start
address of DTB overlaps to the address of kernel/initrd.

Signed-off-by: Jim Shu <jim....@sifive.com>
---

Reviewed-by: Daniel Henrique Barboza <dbarb...@ventanamicro.com>

  hw/riscv/boot.c         | 25 ++++++++++++++++++++++++-
  include/hw/riscv/boot.h |  3 +++
  2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/hw/riscv/boot.c b/hw/riscv/boot.c
index c7478d2365..d22d240854 100644
--- a/hw/riscv/boot.c
+++ b/hw/riscv/boot.c
@@ -70,6 +70,7 @@ char *riscv_plic_hart_config_string(int hart_count)
  void riscv_boot_info_init(RISCVBootInfo *info, RISCVHartArrayState *harts)
  {
      info->kernel_size = 0;
+    info->initrd_size = 0;
      info->is_32bit = riscv_is_32bit(harts);
  }

@@ -213,6 +214,9 @@ static void riscv_load_initrd(MachineState *machine, RISCVBootInfo *info)

          }
      }

+ info->initrd_start = start;

+    info->initrd_size = size;
+
      /* Some RISC-V machines (e.g. opentitan) don't have a fdt. */
      if (fdt) {
          end = start + size;
@@ -309,6 +313,7 @@ uint64_t riscv_compute_fdt_addr(hwaddr dram_base, hwaddr 
dram_size,
      int ret = fdt_pack(ms->fdt);
      hwaddr dram_end, temp;
      int fdtsize;
+    uint64_t dtb_start, dtb_start_limit;

/* Should only fail if we've built a corrupted tree */

      g_assert(ret == 0);
@@ -319,6 +324,17 @@ uint64_t riscv_compute_fdt_addr(hwaddr dram_base, hwaddr 
dram_size,
          exit(1);
      }

+ if (info->initrd_size) {

+        /* If initrd is successfully loaded, place DTB after it. */
+        dtb_start_limit = info->initrd_start + info->initrd_size;
+    } else if (info->kernel_size) {
+        /* If only kernel is successfully loaded, place DTB after it. */
+        dtb_start_limit = info->image_high_addr;
+    } else {
+        /* Otherwise, do not check DTB overlapping */
+        dtb_start_limit = 0;
+    }
+
      /*
       * A dram_size == 0, usually from a MemMapEntry[].size element,
       * means that the DRAM block goes all the way to ms->ram_size.
@@ -338,7 +354,14 @@ uint64_t riscv_compute_fdt_addr(hwaddr dram_base, hwaddr 
dram_size,
          temp = (dram_base < 3072 * MiB) ? MIN(dram_end, 3072 * MiB) : 
dram_end;
      }

- return QEMU_ALIGN_DOWN(temp - fdtsize, 2 * MiB);

+    dtb_start = QEMU_ALIGN_DOWN(temp - fdtsize, 2 * MiB);
+
+    if (dtb_start_limit && (dtb_start < dtb_start_limit)) {
+        error_report("No enough memory to place DTB after kernel/initrd");
+        exit(1);
+    }
+
+    return dtb_start;
  }

/*

diff --git a/include/hw/riscv/boot.h b/include/hw/riscv/boot.h
index 719ee1fe5f..e309cc1a7f 100644
--- a/include/hw/riscv/boot.h
+++ b/include/hw/riscv/boot.h
@@ -32,6 +32,9 @@ typedef struct RISCVBootInfo {
      uint64_t image_low_addr;
      uint64_t image_high_addr;

+ hwaddr initrd_start;

+    ssize_t initrd_size;
+
      bool is_32bit;
  } RISCVBootInfo;