RISC-V: Implement sparsemem

Implement sparsemem support for Risc-v which helps pave the
way for memory hotplug and eventually P2P support.

Introduce Kconfig options for virtual and physical address bits which
are used to calculate the size of the vmemmap and set the
MAX_PHYSMEM_BITS.

The vmemmap is located directly before the VMALLOC region and sized
such that we can allocate enough pages to populate all the virtual
address space in the system (similar to the way it's done in arm64).

During initialization, call memblocks_present() and sparse_init(),
and provide a stub for vmemmap_populate() (all of which is similar to
arm64).

[greentime.hu@sifive.com: fixed pfn_valid, FIXADDR_TOP and fixed a bug
 rebasing onto v5.3]
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andrew Waterman <andrew@sifive.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Michael Clark <michaeljclark@mac.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Zong Li <zong@andestech.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
[paul.walmsley@sifive.com: updated to apply; minor commit message
 reformat]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 86ee362..f392358 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -55,6 +55,7 @@ config RISCV
        select EDAC_SUPPORT
        select ARCH_HAS_GIGANTIC_PAGE
        select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
+       select SPARSEMEM_STATIC if 32BIT
 
 config MMU
        def_bool y
@@ -63,12 +64,32 @@ config ZONE_DMA32
        bool
        default y if 64BIT
 
+config VA_BITS
+       int
+       default 32 if 32BIT
+       default 39 if 64BIT
+
+config PA_BITS
+       int
+       default 34 if 32BIT
+       default 56 if 64BIT
+
 config PAGE_OFFSET
        hex
        default 0xC0000000 if 32BIT && MAXPHYSMEM_2GB
        default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
        default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
 
+config ARCH_FLATMEM_ENABLE
+       def_bool y
+
+config ARCH_SPARSEMEM_ENABLE
+       def_bool y
+       select SPARSEMEM_VMEMMAP_ENABLE
+
+config ARCH_SELECT_MEMORY_MODEL
+       def_bool ARCH_SPARSEMEM_ENABLE
+
 config ARCH_WANT_GENERAL_HUGETLB
        def_bool y
 

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 707e00a..3db261c 100644 (file)
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -110,8 +110,10 @@ extern unsigned long min_low_pfn;
 #define page_to_bus(page)      (page_to_phys(page))
 #define phys_to_page(paddr)    (pfn_to_page(phys_to_pfn(paddr)))
 
+#ifdef CONFIG_FLATMEM
 #define pfn_valid(pfn) \
        (((pfn) >= pfn_base) && (((pfn)-pfn_base) < max_mapnr))
+#endif
 
 #define ARCH_PFN_OFFSET                (pfn_base)
 

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index c24a083..80905b2 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -83,6 +83,19 @@ extern pgd_t swapper_pg_dir[];
 #define __S110 PAGE_SHARED_EXEC
 #define __S111 PAGE_SHARED_EXEC
 
+/*
+ * Roughly size the vmemmap space to be large enough to fit enough
+ * struct pages to map half the virtual address space. Then
+ * position vmemmap directly below the VMALLOC region.
+ */
+#define VMEMMAP_SHIFT \
+       (CONFIG_VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT)
+#define VMEMMAP_SIZE   BIT(VMEMMAP_SHIFT)
+#define VMEMMAP_END    (VMALLOC_START - 1)
+#define VMEMMAP_START  (VMALLOC_START - VMEMMAP_SIZE)
+
+#define vmemmap                ((struct page *)VMEMMAP_START)
+
 /*
  * ZERO_PAGE is a global shared page that is always zero,
  * used for zero-mapped memory areas, etc.

diff --git a/arch/riscv/include/asm/sparsemem.h b/arch/riscv/include/asm/sparsemem.h
new file mode 100644 (file)
index 0000000..b58ba2d
--- /dev/null
+++ b/arch/riscv/include/asm/sparsemem.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_SPARSEMEM_H
+#define __ASM_SPARSEMEM_H
+
+#ifdef CONFIG_SPARSEMEM
+#define MAX_PHYSMEM_BITS       CONFIG_PA_BITS
+#define SECTION_SIZE_BITS      27
+#endif /* CONFIG_SPARSEMEM */
+
+#endif /* __ASM_SPARSEMEM_H */

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 238fc41..f0ba713 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -442,6 +442,16 @@ static void __init setup_vm_final(void)
 void __init paging_init(void)
 {
        setup_vm_final();
+       memblocks_present();
+       sparse_init();
        setup_zero_page();
        zone_sizes_init();
 }
+
+#ifdef CONFIG_SPARSEMEM
+int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
+                              struct vmem_altmap *altmap)
+{
+       return vmemmap_populate_basepages(start, end, node);
+}
+#endif