[kvm-unit-tests PATCH 17/24] riscv: Populate memregions and switch to page allocator

Andrew Jones
2024-01-24T07:19:04Z

Get the memory regions from the DT rather than just assuming we have
enough. Getting memory regions and setting their flags is also a
first step to enabling the MMU. Also switch to the page allocator,
which is a second step to enabling the MMU.

Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
---
lib/riscv/asm/memory_areas.h | 1 +
lib/riscv/setup.c | 55 ++++++++++++++++++++++++++++++++++--
riscv/Makefile | 2 ++
3 files changed, 55 insertions(+), 3 deletions(-)
create mode 100644 lib/riscv/asm/memory_areas.h

diff --git a/lib/riscv/asm/memory_areas.h b/lib/riscv/asm/memory_areas.h
new file mode 100644
index 000000000000..2b34e63502dd
--- /dev/null
+++ b/lib/riscv/asm/memory_areas.h
@@ -0,0 +1 @@
+#include <asm-generic/memory_areas.h>
diff --git a/lib/riscv/setup.c b/lib/riscv/setup.c
index 9ff446b5e171..848ec8e83496 100644
--- a/lib/riscv/setup.c
+++ b/lib/riscv/setup.c
@@ -6,22 +6,31 @@
*/
#include <libcflat.h>
#include <alloc.h>
+#include <alloc_page.h>
#include <alloc_phys.h>
#include <argv.h>
#include <cpumask.h>
#include <devicetree.h>
+#include <memregions.h>
#include <on-cpus.h>
#include <asm/csr.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <asm/setup.h>

+#define VA_BASE ((phys_addr_t)3 * SZ_1G)
+
+#define MAX_DT_MEM_REGIONS 16
+#define NR_MEM_REGIONS (MAX_DT_MEM_REGIONS + 16)
+
char *initrd;
u32 initrd_size;

struct thread_info cpus[NR_CPUS];
int nr_cpus;

+static struct mem_region riscv_mem_regions[NR_MEM_REGIONS + 1];
+
int hartid_to_cpu(unsigned long hartid)
{
int cpu;
@@ -64,10 +73,50 @@ static void cpu_init(void)
cpu0_calls_idle = true;
}

+extern unsigned long _etext;
+
static void mem_init(phys_addr_t freemem_start)
{
- //TODO - for now just assume we've got some memory available
- phys_alloc_init(freemem_start, 16 * SZ_1M);
+ struct mem_region *freemem, *code, *data;
+ phys_addr_t freemem_end, base, top;
+
+ memregions_init(riscv_mem_regions, NR_MEM_REGIONS);
+ memregions_add_dt_regions(MAX_DT_MEM_REGIONS);
+
+ /* Split the region with the code into two regions; code and data */
+ memregions_split((unsigned long)&_etext, &code, &data);
+ assert(code);
+ code->flags |= MR_F_CODE;
+
+ freemem = memregions_find(freemem_start);
+ assert(freemem && !(freemem->flags & (MR_F_IO | MR_F_CODE)));
+
+ freemem_end = freemem->end & PAGE_MASK;
+
+ /*
+ * The assert below is mostly checking that the free memory doesn't
+ * start in the 3G-4G range, which is reserved for virtual addresses,
+ * but it also confirms that there is some free memory (the amount
+ * is arbitrarily selected, but should be sufficient for a unit test)
+ *
+ * TODO: Allow the VA range to shrink and move.
+ */
+ if (freemem_end > VA_BASE)
+ freemem_end = VA_BASE;
+ assert(freemem_end - freemem_start >= SZ_1M * 16);
+
+ /*
+ * TODO: Remove the need for this phys allocator dance, since, as we
+ * can see with the assert, we could have gone straight to the page
+ * allocator.
+ */
+ phys_alloc_init(freemem_start, freemem_end - freemem_start);
+ phys_alloc_set_minimum_alignment(PAGE_SIZE);
+ phys_alloc_get_unused(&base, &top);
+ assert(base == freemem_start && top == freemem_end);
+
+ page_alloc_init_area(0, freemem_start >> PAGE_SHIFT, freemem_end >> PAGE_SHIFT);
+ page_alloc_ops_enable();
}

static void banner(void)
@@ -86,7 +135,7 @@ void setup(const void *fdt, phys_addr_t freemem_start)
u32 fdt_size;
int ret;

- assert(sizeof(long) == 8 || freemem_start < (3ul << 30));
+ assert(sizeof(long) == 8 || freemem_start < VA_BASE);
freemem = (void *)(unsigned long)freemem_start;

/* Move the FDT to the base of free memory */
diff --git a/riscv/Makefile b/riscv/Makefile
index 932f3378264c..ed1a14025ed2 100644
--- a/riscv/Makefile
+++ b/riscv/Makefile
@@ -22,8 +22,10 @@ $(TEST_DIR)/sieve.elf: AUXFLAGS = 0x1
cstart.o = $(TEST_DIR)/cstart.o

cflatobjs += lib/alloc.o
+cflatobjs += lib/alloc_page.o
cflatobjs += lib/alloc_phys.o
cflatobjs += lib/devicetree.o
+cflatobjs += lib/memregions.o
cflatobjs += lib/on-cpus.o
cflatobjs += lib/riscv/bitops.o
cflatobjs += lib/riscv/io.o
--
2.43.0