riscv: mm: Define DIRECT_MAP_PHYSMEM_END

On RISC-V, the actual mappable range of physical address space is
dependent on the current MMU mode i.e. satp_mode (See
Documentation/arch/riscv/vm-layout.rst).

Define the DIRECT_MAP_PHYSMEM_END macro based on the existing virtual
address space layout macros to expose this information to
get_free_mem_region(). Otherwise, it returns a region that couldn't be
mapped, which breaks ZONE_DEVICE.

Cc: stable@vger.kernel.org # v6.13+
Tested-by: Han Gao <gaohan@iscas.ac.cn> # SG2044
Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Link: https://patch.msgid.link/20260309-riscv-sparsemem-vmemmap-limits-v1-2-f40efe18e3cd@iscas.ac.cn
Signed-off-by: Paul Walmsley <pjw@kernel.org>

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index a1a7c6520a095461d7028161c84f5617489ffbd8..5d5756bda82e3d44c68518930b9ef41881295709 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -93,6 +93,16 @@
  */
 #define vmemmap                ((struct page *)VMEMMAP_START - vmemmap_start_pfn)
 
+/* Needed to limit get_free_mem_region() */
+#if defined(CONFIG_FLATMEM)
+#define DIRECT_MAP_PHYSMEM_END (phys_ram_base + KERN_VIRT_SIZE - 1)
+#elif defined(CONFIG_SPARSEMEM_VMEMMAP)
+#define DIRECT_MAP_PHYSMEM_END \
+       ((vmemmap_start_pfn + VMEMMAP_SIZE / sizeof(struct page)) * PAGE_SIZE - 1)
+#elif defined(CONFIG_SPARSEMEM)
+/* DIRECT_MAP_PHYSMEM_END is not limited by VA space assignment in this case */
+#endif
+
 #define PCI_IO_SIZE      SZ_16M
 #define PCI_IO_END       VMEMMAP_START
 #define PCI_IO_START     (PCI_IO_END - PCI_IO_SIZE)