[PATCH v5 5/9] riscv: add ARCH_HAS_SET_DIRECT_MAP support

[Zong Li <zong.li@sifive.com>]

Add set_direct_map_*() functions for setting the direct map alias for
the page to its default permissions and to an invalid state that cannot
be cached in a TLB. (See d253ca0c ("x86/mm/cpa: Add set_direct_map_*()
functions")) Add a similar implementation for RISC-V.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/Kconfig                  |  1 +
 arch/riscv/include/asm/set_memory.h |  3 +++
 arch/riscv/mm/pageattr.c            | 24 ++++++++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 9044e0dd95ea..a94d0f064d9c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -59,6 +59,7 @@ config RISCV
 	select HAVE_EBPF_JIT if 64BIT
 	select EDAC_SUPPORT
 	select ARCH_HAS_GIGANTIC_PAGE
+	select ARCH_HAS_SET_DIRECT_MAP
 	select ARCH_HAS_SET_MEMORY
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select SPARSEMEM_STATIC if 32BIT
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index 79a810f0f38b..620d81c372d9 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -21,4 +21,7 @@ static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
+int set_direct_map_invalid_noflush(struct page *page);
+int set_direct_map_default_noflush(struct page *page);
+
 #endif /* _ASM_RISCV_SET_MEMORY_H */
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index fcd59ef2835b..7be6cd67e2ef 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -148,3 +148,27 @@ int set_memory_nx(unsigned long addr, int numpages)
 {
 	return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
 }
+
+int set_direct_map_invalid_noflush(struct page *page)
+{
+	unsigned long start = (unsigned long)page_address(page);
+	unsigned long end = start + PAGE_SIZE;
+	struct pageattr_masks masks = {
+		.set_mask = __pgprot(0),
+		.clear_mask = __pgprot(_PAGE_PRESENT)
+	};
+
+	return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
+}
+
+int set_direct_map_default_noflush(struct page *page)
+{
+	unsigned long start = (unsigned long)page_address(page);
+	unsigned long end = start + PAGE_SIZE;
+	struct pageattr_masks masks = {
+		.set_mask = PAGE_KERNEL,
+		.clear_mask = __pgprot(0)
+	};
+
+	return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
+}
-- 
2.26.0