riscv/sifive_u: Add L2-LIM cache memory

On reset only a single L2 cache way is enabled, the others are exposed
as memory that can be used by early boot firmware. This L2 region is
generally disabled using the WayEnable register at a later stage in the
boot process. To allow firmware to target QEMU and the HiFive Unleashed
let's add the L2 LIM (LooselyIntegrated Memory).

Ideally we would want to adjust the size of this chunk of memory as the
L2 Cache Controller WayEnable register is incremented. Unfortunately I
don't see a nice way to handle reducing or blocking out the L2 LIM while
still allowing it be re returned to all enabled from a reset.

Signed-off-by: Alistair Francis <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Signed-off-by: Palmer Dabbelt <[email protected]>

diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index 1ac51e36321a7583fd1d492bb6a0ca43251aa010..fbaa3a234eae0e99ce7d238a34f6a967f7f3cb40 100644 (file)
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -65,6 +65,7 @@ static const struct MemmapEntry {
     [SIFIVE_U_DEBUG] =    {        0x0,      0x100 },
     [SIFIVE_U_MROM] =     {     0x1000,    0x11000 },
     [SIFIVE_U_CLINT] =    {  0x2000000,    0x10000 },
+    [SIFIVE_U_L2LIM] =    {  0x8000000,  0x2000000 },
     [SIFIVE_U_PLIC] =     {  0xc000000,  0x4000000 },
     [SIFIVE_U_PRCI] =     { 0x10000000,     0x1000 },
     [SIFIVE_U_UART0] =    { 0x10010000,     0x1000 },
@@ -432,6 +433,7 @@ static void riscv_sifive_u_soc_realize(DeviceState *dev, Error **errp)
     const struct MemmapEntry *memmap = sifive_u_memmap;
     MemoryRegion *system_memory = get_system_memory();
     MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
+    MemoryRegion *l2lim_mem = g_new(MemoryRegion, 1);
     qemu_irq plic_gpios[SIFIVE_U_PLIC_NUM_SOURCES];
     char *plic_hart_config;
     size_t plic_hart_config_len;
@@ -460,6 +462,20 @@ static void riscv_sifive_u_soc_realize(DeviceState *dev, Error **errp)
     memory_region_add_subregion(system_memory, memmap[SIFIVE_U_MROM].base,
                                 mask_rom);
 
+    /*
+     * Add L2-LIM at reset size.
+     * This should be reduced in size as the L2 Cache Controller WayEnable
+     * register is incremented. Unfortunately I don't see a nice (or any) way
+     * to handle reducing or blocking out the L2 LIM while still allowing it
+     * be re returned to all enabled after a reset. For the time being, just
+     * leave it enabled all the time. This won't break anything, but will be
+     * too generous to misbehaving guests.
+     */
+    memory_region_init_ram(l2lim_mem, NULL, "riscv.sifive.u.l2lim",
+                           memmap[SIFIVE_U_L2LIM].size, &error_fatal);
+    memory_region_add_subregion(system_memory, memmap[SIFIVE_U_L2LIM].base,
+                                l2lim_mem);
+
     /* create PLIC hart topology configuration string */
     plic_hart_config_len = (strlen(SIFIVE_U_PLIC_HART_CONFIG) + 1) *
                            ms->smp.cpus;

diff --git a/include/hw/riscv/sifive_u.h b/include/hw/riscv/sifive_u.h
index 4850805ee7c968b0125d5e9a6d477f9c29eb3e3a..66ee76a7800360745136e56aa245f844a41e929b 100644 (file)
--- a/include/hw/riscv/sifive_u.h
+++ b/include/hw/riscv/sifive_u.h
@@ -58,6 +58,7 @@ enum {
     SIFIVE_U_DEBUG,
     SIFIVE_U_MROM,
     SIFIVE_U_CLINT,
+    SIFIVE_U_L2LIM,
     SIFIVE_U_PLIC,
     SIFIVE_U_PRCI,
     SIFIVE_U_UART0,