Merge patch series "riscv, mm: detect svnapot cpu support at runtime"

Qinglin Pan <panqinglin00@gmail.com> says:

Svnapot is a RISC-V extension for marking contiguous 4K pages as a non-4K
page. This patch set is for using Svnapot in hugetlb fs and huge vmap.

This patchset adds a Kconfig item for using Svnapot in
"Platform type"->"SVNAPOT extension support". Its default value is on,
and people can set it off if they don't allow kernel to detect Svnapot
hardware support and leverage it.

Tested on:
  - qemu rv64 with "Svnapot support" off and svnapot=true.
  - qemu rv64 with "Svnapot support" on and svnapot=true.
  - qemu rv64 with "Svnapot support" off and svnapot=false.
  - qemu rv64 with "Svnapot support" on and svnapot=false.

* b4-shazam-merge:
  riscv: mm: support Svnapot in huge vmap
  riscv: mm: support Svnapot in hugetlb page
  riscv: mm: modify pte format for Svnapot

Link: https://lore.kernel.org/r/20230209131647.17245-1-panqinglin00@gmail.com
[Palmer: fix up the feature ordering in the merge]
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

6 files changed, 166 insertions, 8 deletions

diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
index ec19d6afc896..fe6f23006641 100644
--- a/arch/riscv/include/asm/hugetlb.h
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -2,7 +2,6 @@
 #ifndef _ASM_RISCV_HUGETLB_H
 #define _ASM_RISCV_HUGETLB_H
 
-#include <asm-generic/hugetlb.h>
 #include <asm/page.h>
 
 static inline void arch_clear_hugepage_flags(struct page *page)
@@ -11,4 +10,37 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 }
 #define arch_clear_hugepage_flags arch_clear_hugepage_flags
 
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
+#define __HAVE_ARCH_HUGE_PTE_CLEAR
+void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
+		    pte_t *ptep, unsigned long sz);
+
+#define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
+void set_huge_pte_at(struct mm_struct *mm,
+		     unsigned long addr, pte_t *ptep, pte_t pte);
+
+#define __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
+pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
+			      unsigned long addr, pte_t *ptep);
+
+#define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
+pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+			    unsigned long addr, pte_t *ptep);
+
+#define __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT
+void huge_ptep_set_wrprotect(struct mm_struct *mm,
+			     unsigned long addr, pte_t *ptep);
+
+#define __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS
+int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+			       unsigned long addr, pte_t *ptep,
+			       pte_t pte, int dirty);
+
+pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags);
+#define arch_make_huge_pte arch_make_huge_pte
+
+#endif /*CONFIG_RISCV_ISA_SVNAPOT*/
+
+#include <asm-generic/hugetlb.h>
+
 #endif /* _ASM_RISCV_HUGETLB_H */
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index e3021b2590de..0ed15c2a2816 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -42,6 +42,7 @@
 #define RISCV_ISA_EXT_ZBB		30
 #define RISCV_ISA_EXT_ZICBOM		31
 #define RISCV_ISA_EXT_ZIHINTPAUSE	32
+#define RISCV_ISA_EXT_SVNAPOT		33
 
 #define RISCV_ISA_EXT_MAX		64
 #define RISCV_ISA_EXT_NAME_LEN_MAX	32
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 7fed7c431928..0f3220e253bc 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -16,11 +16,6 @@
 #define PAGE_SIZE	(_AC(1, UL) << PAGE_SHIFT)
 #define PAGE_MASK	(~(PAGE_SIZE - 1))
 
-#ifdef CONFIG_64BIT
-#define HUGE_MAX_HSTATE		2
-#else
-#define HUGE_MAX_HSTATE		1
-#endif
 #define HPAGE_SHIFT		PMD_SHIFT
 #define HPAGE_SIZE		(_AC(1, UL) << HPAGE_SHIFT)
 #define HPAGE_MASK              (~(HPAGE_SIZE - 1))
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 42a042c0e13e..7a5097202e15 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -79,6 +79,40 @@ typedef struct {
 #define _PAGE_PFN_MASK  GENMASK(53, 10)
 
 /*
+ * [63] Svnapot definitions:
+ * 0 Svnapot disabled
+ * 1 Svnapot enabled
+ */
+#define _PAGE_NAPOT_SHIFT	63
+#define _PAGE_NAPOT		BIT(_PAGE_NAPOT_SHIFT)
+/*
+ * Only 64KB (order 4) napot ptes supported.
+ */
+#define NAPOT_CONT_ORDER_BASE 4
+enum napot_cont_order {
+	NAPOT_CONT64KB_ORDER = NAPOT_CONT_ORDER_BASE,
+	NAPOT_ORDER_MAX,
+};
+
+#define for_each_napot_order(order)						\
+	for (order = NAPOT_CONT_ORDER_BASE; order < NAPOT_ORDER_MAX; order++)
+#define for_each_napot_order_rev(order)						\
+	for (order = NAPOT_ORDER_MAX - 1;					\
+	     order >= NAPOT_CONT_ORDER_BASE; order--)
+#define napot_cont_order(val)	(__builtin_ctzl((val.pte >> _PAGE_PFN_SHIFT) << 1))
+
+#define napot_cont_shift(order)	((order) + PAGE_SHIFT)
+#define napot_cont_size(order)	BIT(napot_cont_shift(order))
+#define napot_cont_mask(order)	(~(napot_cont_size(order) - 1UL))
+#define napot_pte_num(order)	BIT(order)
+
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
+#define HUGE_MAX_HSTATE		(2 + (NAPOT_ORDER_MAX - NAPOT_CONT_ORDER_BASE))
+#else
+#define HUGE_MAX_HSTATE		2
+#endif
+
+/*
  * [62:61] Svpbmt Memory Type definitions:
  *
  *  00 - PMA    Normal Cacheable, No change to implied PMA memory type
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index ab05f892d317..3303fc03d724 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -264,10 +264,47 @@ static inline pte_t pud_pte(pud_t pud)
 	return __pte(pud_val(pud));
 }
 
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
+
+static __always_inline bool has_svnapot(void)
+{
+	return riscv_has_extension_likely(RISCV_ISA_EXT_SVNAPOT);
+}
+
+static inline unsigned long pte_napot(pte_t pte)
+{
+	return pte_val(pte) & _PAGE_NAPOT;
+}
+
+static inline pte_t pte_mknapot(pte_t pte, unsigned int order)
+{
+	int pos = order - 1 + _PAGE_PFN_SHIFT;
+	unsigned long napot_bit = BIT(pos);
+	unsigned long napot_mask = ~GENMASK(pos, _PAGE_PFN_SHIFT);
+
+	return __pte((pte_val(pte) & napot_mask) | napot_bit | _PAGE_NAPOT);
+}
+
+#else
+
+static __always_inline bool has_svnapot(void) { return false; }
+
+static inline unsigned long pte_napot(pte_t pte)
+{
+	return 0;
+}
+
+#endif /* CONFIG_RISCV_ISA_SVNAPOT */
+
 /* Yields the page frame number (PFN) of a page table entry */
 static inline unsigned long pte_pfn(pte_t pte)
 {
-	return __page_val_to_pfn(pte_val(pte));
+	unsigned long res  = __page_val_to_pfn(pte_val(pte));
+
+	if (has_svnapot() && pte_napot(pte))
+		res = res & (res - 1UL);
+
+	return res;
 }
 
 #define pte_page(x)     pfn_to_page(pte_pfn(x))
diff --git a/arch/riscv/include/asm/vmalloc.h b/arch/riscv/include/asm/vmalloc.h
index 48da5371f1e9..58d3e447f191 100644
--- a/arch/riscv/include/asm/vmalloc.h
+++ b/arch/riscv/include/asm/vmalloc.h
@@ -17,6 +17,65 @@ static inline bool arch_vmap_pmd_supported(pgprot_t prot)
 	return true;
 }
 
-#endif
+#ifdef CONFIG_RISCV_ISA_SVNAPOT
+#include <linux/pgtable.h>
 
+#define arch_vmap_pte_range_map_size arch_vmap_pte_range_map_size
+static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr, unsigned long end,
+							 u64 pfn, unsigned int max_page_shift)
+{
+	unsigned long map_size = PAGE_SIZE;
+	unsigned long size, order;
+
+	if (!has_svnapot())
+		return map_size;
+
+	for_each_napot_order_rev(order) {
+		if (napot_cont_shift(order) > max_page_shift)
+			continue;
+
+		size = napot_cont_size(order);
+		if (end - addr < size)
+			continue;
+
+		if (!IS_ALIGNED(addr, size))
+			continue;
+
+		if (!IS_ALIGNED(PFN_PHYS(pfn), size))
+			continue;
+
+		map_size = size;
+		break;
+	}
+
+	return map_size;
+}
+
+#define arch_vmap_pte_supported_shift arch_vmap_pte_supported_shift
+static inline int arch_vmap_pte_supported_shift(unsigned long size)
+{
+	int shift = PAGE_SHIFT;
+	unsigned long order;
+
+	if (!has_svnapot())
+		return shift;
+
+	WARN_ON_ONCE(size >= PMD_SIZE);
+
+	for_each_napot_order_rev(order) {
+		if (napot_cont_size(order) > size)
+			continue;
+
+		if (!IS_ALIGNED(size, napot_cont_size(order)))
+			continue;
+
+		shift = napot_cont_shift(order);
+		break;
+	}
+
+	return shift;
+}
+
+#endif /* CONFIG_RISCV_ISA_SVNAPOT */
+#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
 #endif /* _ASM_RISCV_VMALLOC_H */