[PATCH v2 0/4] riscv: mm: add Svnapot support

[PATCH v2 0/4] riscv: mm: add Svnapot support

[panqinglin2020]

From: Qinglin Pan <panqinglin2020@iscas.ac.cn>

Svnapot is a RISC-V extension for marking contiguous 4K pages as a non-4K
page. This patch set is for using Svnapot in Linux Kernel's boot process
and hugetlb fs.

This patchset adds a Kconfig item for using Svnapot in
"Platform type"->"Svnapot support". Its default value is off, and people can set
it on if they 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.

Changes in v2:
  - detect Svnapot hardware support at boot time.

Qinglin Pan (4):
  mm: modify pte format for Svnapot
  mm: support Svnapot in physical page linear-mapping
  mm: support Svnapot in hugetlb page
  mm: support Svnapot in huge vmap

 arch/riscv/Kconfig                   |  10 +-
 arch/riscv/include/asm/errata_list.h |  24 ++-
 arch/riscv/include/asm/hugetlb.h     |  31 +++-
 arch/riscv/include/asm/hwcap.h       |   1 +
 arch/riscv/include/asm/page.h        |   2 +-
 arch/riscv/include/asm/pgtable-64.h  |  14 ++
 arch/riscv/include/asm/pgtable.h     |  67 +++++++-
 arch/riscv/include/asm/vmalloc.h     |  20 +++
 arch/riscv/kernel/cpu.c              |   1 +
 arch/riscv/kernel/cpufeature.c       |  18 ++
 arch/riscv/mm/hugetlbpage.c          | 239 ++++++++++++++++++++++++++-
 arch/riscv/mm/init.c                 |  28 +++-
 12 files changed, 442 insertions(+), 13 deletions(-)

-- 
2.35.1


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[PATCH v2 1/4] riscv, mm: detect svnapot cpu support at runtime

[panqinglin2020]

From: Qinglin Pan <panqinglin2020@iscas.ac.cn>

This patch add two erratas to enable/disable svnapot support, patches code
dynamicly when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
option is set. It will influence the behavior of has_svnapot function and
pte_pfn function. All code dependent on svnapot should make sure that has_svnapot
return true firstly.

Also, this patch modifies PTE definition for Svnapot, and creates some functions in
pgtable.h to mark a PTE as napot and check if it is a Svnapot PTE.
Until now, only 64KB napot size is supported in draft spec, so some macros
has only 64KB version.

Yours,
Qinglin

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index b17fd4666b0c..c5e1629a6033 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -385,6 +385,13 @@ config FPU
 
 	  If you don't know what to do here, say Y.
 
+config SVNAPOT
+	bool "Svnapot support"
+	default n
+	help
+	  Select if your CPU supports Svnapot and you want to enable it when
+	  kernel is booting.
+
 endmenu # "Platform type"
 
 menu "Kernel features"
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
index 9e2888dbb5b1..84ad32075637 100644
--- a/arch/riscv/include/asm/errata_list.h
+++ b/arch/riscv/include/asm/errata_list.h
@@ -20,7 +20,8 @@
 #endif
 
 #define	CPUFEATURE_SVPBMT 0
-#define	CPUFEATURE_NUMBER 1
+#define	CPUFEATURE_SVNAPOT 1
+#define	CPUFEATURE_NUMBER 2
 
 #ifdef __ASSEMBLY__
 
@@ -93,6 +94,27 @@ asm volatile(ALTERNATIVE(						\
 #define ALT_THEAD_PMA(_val)
 #endif
 
+#define ALT_SVNAPOT(_val)						\
+asm(ALTERNATIVE("li %0, 0", "li %0, 1", 0,				\
+		CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)			\
+		: "=r"(_val) :)
+
+#define ALT_SVNAPOT_PTE_PFN(_val, _napot_shift, _pfn_mask, _pfn_shift)	\
+asm(ALTERNATIVE("and %0, %1, %2\n\t"					\
+		"srli %0, %0, %3\n\t"					\
+		"nop\n\tnop\n\tnop",					\
+		"srli t3, %1, %4\n\t"					\
+		"and %0, %1, %2\n\t"					\
+		"srli %0, %0, %3\n\t"					\
+		"sub  t4, %0, t3\n\t"					\
+		"and  %0, %0, t4",					\
+		0, CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)			\
+		: "+r"(_val)						\
+		: "r"(_val),						\
+		  "r"(_pfn_mask),					\
+		  "i"(_pfn_shift),					\
+		  "i"(_napot_shift))
+
 #endif /* __ASSEMBLY__ */
 
 #endif
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index e48eebdd2631..292ab93321e3 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -54,6 +54,7 @@ extern unsigned long elf_hwcap;
 enum riscv_isa_ext_id {
 	RISCV_ISA_EXT_SSCOFPMF = RISCV_ISA_EXT_BASE,
 	RISCV_ISA_EXT_SVPBMT,
+	RISCV_ISA_EXT_SVNAPOT,
 	RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX,
 };
 
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index 5c2aba5efbd0..e8463515a46c 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -74,6 +74,20 @@ 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      (1UL << _PAGE_NAPOT_SHIFT)
+#define NAPOT_CONT64KB_ORDER 4UL
+#define NAPOT_CONT64KB_SHIFT (NAPOT_CONT64KB_ORDER + PAGE_SHIFT)
+#define NAPOT_CONT64KB_SIZE (1UL << NAPOT_CONT64KB_SHIFT)
+#define NAPOT_CONT64KB_MASK (NAPOT_CONT64KB_SIZE - 1)
+#define NAPOT_64KB_PTE_NUM (1UL << NAPOT_CONT64KB_ORDER)
+#define NAPOT_64KB_MASK (7UL << _PAGE_PFN_SHIFT)
+
 /*
  * [62:61] Svpbmt Memory Type definitions:
  *
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 1d1be9d9419c..34c4be9de79e 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -284,10 +284,38 @@ static inline pte_t pud_pte(pud_t pud)
 	return __pte(pud_val(pud));
 }
 
+static inline bool has_svnapot(void) {
+	u64 _val;
+	ALT_SVNAPOT(_val);
+	return _val;
+}
+
+#ifdef CONFIG_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)
+{
+	unsigned long napot_bits = (1UL << (order - 1)) << _PAGE_PFN_SHIFT;
+	unsigned long lower_prot =
+		pte_val(pte) & ((1UL << _PAGE_PFN_SHIFT) - 1UL);
+	unsigned long upper_prot = (pte_val(pte) >> _PAGE_PFN_SHIFT)
+				   << _PAGE_PFN_SHIFT;
+
+	return __pte(upper_prot | napot_bits | lower_prot | _PAGE_NAPOT);
+}
+#endif /* CONFIG_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 _val  = pte_val(pte);
+	ALT_SVNAPOT_PTE_PFN(_val, _PAGE_NAPOT_SHIFT,
+			_PAGE_PFN_MASK, _PAGE_PFN_SHIFT);
+	return _val;
 }
 
 #define pte_page(x)     pfn_to_page(pte_pfn(x))
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index fba9e9f46a8c..9f1113fa2b96 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -89,6 +89,7 @@ int riscv_of_parent_hartid(struct device_node *node)
 static struct riscv_isa_ext_data isa_ext_arr[] = {
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
 	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
+	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
 	__RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
 };
 
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 1b3ec44e25f5..9f38b7d02f2a 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -198,6 +198,7 @@ void __init riscv_fill_hwcap(void)
 			} else {
 				SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
 				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
+				SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
 			}
 #undef SET_ISA_EXT_MAP
 		}
@@ -259,6 +260,20 @@ static bool __init_or_module cpufeature_probe_svpbmt(unsigned int stage)
 	return false;
 }
 
+static bool __init_or_module cpufeature_probe_svnapot(unsigned int stage)
+{
+#ifdef CONFIG_SVNAPOT
+	switch (stage) {
+	case RISCV_ALTERNATIVES_EARLY_BOOT:
+		return false;
+	default:
+		return riscv_isa_extension_available(NULL, SVNAPOT);
+	}
+#endif
+
+	return false;
+}
+
 /*
  * Probe presence of individual extensions.
  *
@@ -273,6 +288,9 @@ static u32 __init_or_module cpufeature_probe(unsigned int stage)
 	if (cpufeature_probe_svpbmt(stage))
 		cpu_req_feature |= (1U << CPUFEATURE_SVPBMT);
 
+	if (cpufeature_probe_svnapot(stage))
+		cpu_req_feature |= (1U << CPUFEATURE_SVNAPOT);
+
 	return cpu_req_feature;
 }
 
-- 
2.35.1


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[PATCH v2 2/4] mm: support Svnapot in physical page linear-mapping

[panqinglin2020]

From: Qinglin Pan <panqinglin2020@iscas.ac.cn>

Svnapot is powerful when a physical region is going to mapped to a
virtual region. Kernel will do like this when mapping all allocable
physical pages to kernel vm space. This patch modify the
create_pte_mapping function used in linear-mapping procedure, so the
kernel can be able to use Svnapot when both address and length of
physical region are 64KB align. Code here will be executed only when
other size huge page is not suitable, so it can be an addition of
PMD_SIZE and PUD_SIZE mapping.

This patch also modifies the best_map_size function to give map_size
many times instead of only once, so a memory region can be mapped by
both PMD_SIZE and 64KB napot size.

It is tested by setting qemu's memory to a 262272k region, and the
kernel can boot successfully.

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index d466ec670e1f..3c766e7325aa 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -350,8 +350,20 @@ static void __init create_pte_mapping(pte_t *ptep,
 {
 	uintptr_t pte_idx = pte_index(va);
 
-	BUG_ON(sz != PAGE_SIZE);
+#ifdef CONFIG_SVNAPOT
+	pte_t pte;
+	if (has_svnapot() && sz == NAPOT_CONT64KB_SIZE) {
+		do {
+			pte = pfn_pte(PFN_DOWN(pa), prot);
+			ptep[pte_idx] = pte_mknapot(pte, NAPOT_CONT64KB_ORDER);
+			pte_idx++;
+			sz -= PAGE_SIZE;
+		} while (sz > 0);
+		return;
+	}
+#endif
 
+	BUG_ON(sz != PAGE_SIZE);
 	if (pte_none(ptep[pte_idx]))
 		ptep[pte_idx] = pfn_pte(PFN_DOWN(pa), prot);
 }
@@ -649,10 +661,18 @@ void __init create_pgd_mapping(pgd_t *pgdp,
 static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
 {
 	/* Upgrade to PMD_SIZE mappings whenever possible */
-	if ((base & (PMD_SIZE - 1)) || (size & (PMD_SIZE - 1)))
+	base &= PMD_SIZE - 1;
+	if (!base && size >= PMD_SIZE)
+		return PMD_SIZE;
+
+	if (!has_svnapot())
 		return PAGE_SIZE;
 
-	return PMD_SIZE;
+	base &= NAPOT_CONT64KB_SIZE - 1;
+	if (!base && size >= NAPOT_CONT64KB_SIZE)
+		return NAPOT_CONT64KB_SIZE;
+
+	return PAGE_SIZE;
 }
 
 #ifdef CONFIG_XIP_KERNEL
@@ -1087,9 +1107,9 @@ static void __init setup_vm_final(void)
 		if (end >= __pa(PAGE_OFFSET) + memory_limit)
 			end = __pa(PAGE_OFFSET) + memory_limit;
 
-		map_size = best_map_size(start, end - start);
 		for (pa = start; pa < end; pa += map_size) {
 			va = (uintptr_t)__va(pa);
+			map_size = best_map_size(pa, end - pa);
 
 			create_pgd_mapping(swapper_pg_dir, va, pa, map_size,
 					   pgprot_from_va(va));
-- 
2.35.1


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[PATCH v2 3/4] mm: support Svnapot in hugetlb page

[panqinglin2020]

From: Qinglin Pan <panqinglin2020@iscas.ac.cn>

Svnapot can be used to support 64KB hugetlb page, so it can become a new
option when using hugetlbfs. This patch adds a basic implementation of
hugetlb page, and support 64KB as a size in it by using Svnapot.

For test, boot kernel with command line contains "default_hugepagesz=64K
hugepagesz=64K hugepages=20" and run a simple test like this:

int main() {
	void *addr;
	addr = mmap(NULL, 64 * 1024, PROT_WRITE | PROT_READ,
			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_HUGE_64KB, -1, 0);
	printf("back from mmap \n");
	long *ptr = (long *)addr;
	unsigned int i = 0;
	for(; i < 8 * 1024;i += 512) {
		printf("%lp \n", ptr);
		*ptr = 0xdeafabcd12345678;
		ptr += 512;
	}
	ptr = (long *)addr;
	i = 0;
	for(; i < 8 * 1024;i += 512) {
		if (*ptr != 0xdeafabcd12345678) {
			printf("failed! 0x%lx \n", *ptr);
			break;
		}
		ptr += 512;
	}
	if(i == 8 * 1024)
		printf("simple test passed!\n");
}

And it should be passed.

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c5e1629a6033..a1fcdd04b12c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -43,7 +43,7 @@ config RISCV
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
 	select ARCH_WANT_FRAME_POINTERS
-	select ARCH_WANT_GENERAL_HUGETLB
+	select ARCH_WANT_GENERAL_HUGETLB if !SVNAPOT
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
 	select BUILDTIME_TABLE_SORT if MMU
diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
index a5c2ca1d1cd8..3fdfe138597b 100644
--- a/arch/riscv/include/asm/hugetlb.h
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -2,7 +2,36 @@
 #ifndef _ASM_RISCV_HUGETLB_H
 #define _ASM_RISCV_HUGETLB_H
 
-#include <asm-generic/hugetlb.h>
 #include <asm/page.h>
 
+#ifdef CONFIG_SVNAPOT
+extern 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
+#define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
+extern 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
+extern pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
+				     unsigned long addr, pte_t *ptep);
+#define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
+extern pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+				  unsigned long addr, pte_t *ptep);
+#define __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS
+extern int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+				      unsigned long addr, pte_t *ptep,
+				      pte_t pte, int dirty);
+#define __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT
+extern void huge_ptep_set_wrprotect(struct mm_struct *mm,
+				    unsigned long addr, pte_t *ptep);
+#define __HAVE_ARCH_HUGE_PTE_CLEAR
+extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
+			   pte_t *ptep, unsigned long sz);
+#define set_huge_swap_pte_at riscv_set_huge_swap_pte_at
+extern void riscv_set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
+				 pte_t *ptep, pte_t pte, unsigned long sz);
+#endif /*CONFIG_SVNAPOT*/
+
+#include <asm-generic/hugetlb.h>
+
 #endif /* _ASM_RISCV_HUGETLB_H */
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 1526e410e802..ef40ba329709 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -17,7 +17,7 @@
 #define PAGE_MASK	(~(PAGE_SIZE - 1))
 
 #ifdef CONFIG_64BIT
-#define HUGE_MAX_HSTATE		2
+#define HUGE_MAX_HSTATE		3
 #else
 #define HUGE_MAX_HSTATE		1
 #endif
diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
index 932dadfdca54..3cf167d9d9ac 100644
--- a/arch/riscv/mm/hugetlbpage.c
+++ b/arch/riscv/mm/hugetlbpage.c
@@ -2,6 +2,228 @@
 #include <linux/hugetlb.h>
 #include <linux/err.h>
 
+#ifdef CONFIG_SVNAPOT
+pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long addr, unsigned long sz)
+{
+	pgd_t *pgdp = pgd_offset(mm, addr);
+	p4d_t *p4dp = p4d_alloc(mm, pgdp, addr);
+	pud_t *pudp = pud_alloc(mm, p4dp, addr);
+	pmd_t *pmdp = pmd_alloc(mm, pudp, addr);
+
+	if (sz == NAPOT_CONT64KB_SIZE) {
+		if (!pmdp)
+			return NULL;
+		WARN_ON(addr & (sz - 1));
+		return pte_alloc_map(mm, pmdp, addr);
+	}
+
+	return NULL;
+}
+
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
+{
+	pgd_t *pgdp;
+	p4d_t *p4dp;
+	pud_t *pudp;
+	pmd_t *pmdp;
+	pte_t *ptep = NULL;
+
+	pgdp = pgd_offset(mm, addr);
+	if (!pgd_present(READ_ONCE(*pgdp)))
+		return NULL;
+
+	p4dp = p4d_offset(pgdp, addr);
+	if (!p4d_present(READ_ONCE(*p4dp)))
+		return NULL;
+
+	pudp = pud_offset(p4dp, addr);
+	if (!pud_present(READ_ONCE(*pudp)))
+		return NULL;
+
+	pmdp = pmd_offset(pudp, addr);
+	if (!pmd_present(READ_ONCE(*pmdp)))
+		return NULL;
+
+	if (sz == NAPOT_CONT64KB_SIZE)
+		ptep = pte_offset_kernel(pmdp, (addr & ~NAPOT_CONT64KB_MASK));
+
+	return ptep;
+}
+
+int napot_pte_num(pte_t pte)
+{
+	if (!(pte_val(pte) & NAPOT_64KB_MASK))
+		return NAPOT_64KB_PTE_NUM;
+
+	pr_warn("%s: unrecognized napot pte size 0x%lx\n",
+		__func__, pte_val(pte));
+	return 1;
+}
+
+static pte_t get_clear_flush(struct mm_struct *mm,
+			     unsigned long addr,
+			     pte_t *ptep,
+			     unsigned long pte_num)
+{
+	pte_t orig_pte = huge_ptep_get(ptep);
+	bool valid = pte_val(orig_pte);
+	unsigned long i, saddr = addr;
+
+	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++) {
+		pte_t pte = ptep_get_and_clear(mm, addr, ptep);
+
+		if (pte_dirty(pte))
+			orig_pte = pte_mkdirty(orig_pte);
+
+		if (pte_young(pte))
+			orig_pte = pte_mkyoung(orig_pte);
+	}
+
+	if (valid) {
+		struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
+
+		flush_tlb_range(&vma, saddr, addr);
+	}
+	return orig_pte;
+}
+
+static void clear_flush(struct mm_struct *mm,
+			     unsigned long addr,
+			     pte_t *ptep,
+			     unsigned long pte_num)
+{
+	struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
+	unsigned long i, saddr = addr;
+
+	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++)
+		pte_clear(mm, addr, ptep);
+
+	flush_tlb_range(&vma, saddr, addr);
+}
+
+pte_t arch_make_huge_pte(pte_t entry, unsigned int shift,
+				       vm_flags_t flags)
+{
+	if (shift == NAPOT_CONT64KB_SHIFT)
+		entry = pte_mknapot(entry, NAPOT_CONT64KB_SHIFT - PAGE_SHIFT);
+
+	return entry;
+}
+
+void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+			    pte_t *ptep, pte_t pte)
+{
+	int i;
+	int pte_num;
+
+	if (!pte_napot(pte)) {
+		set_pte_at(mm, addr, ptep, pte);
+		return;
+	}
+
+	pte_num = napot_pte_num(pte);
+	for (i = 0; i < pte_num; i++, ptep++, addr += PAGE_SIZE)
+		set_pte_at(mm, addr, ptep, pte);
+}
+
+int huge_ptep_set_access_flags(struct vm_area_struct *vma,
+				      unsigned long addr, pte_t *ptep,
+				      pte_t pte, int dirty)
+{
+	pte_t orig_pte;
+	int i;
+	int pte_num;
+
+	if (!pte_napot(pte))
+		return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
+
+	pte_num = napot_pte_num(pte);
+	ptep = huge_pte_offset(vma->vm_mm, addr, NAPOT_CONT64KB_SIZE);
+	orig_pte = huge_ptep_get(ptep);
+
+	if (pte_dirty(orig_pte))
+		pte = pte_mkdirty(pte);
+
+	if (pte_young(orig_pte))
+		pte = pte_mkyoung(pte);
+
+	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++)
+		ptep_set_access_flags(vma, addr, ptep, pte, dirty);
+
+	return true;
+}
+
+pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
+				     unsigned long addr, pte_t *ptep)
+{
+	int pte_num;
+	pte_t orig_pte = huge_ptep_get(ptep);
+
+	if (!pte_napot(orig_pte))
+		return ptep_get_and_clear(mm, addr, ptep);
+
+	pte_num = napot_pte_num(orig_pte);
+	return get_clear_flush(mm, addr, ptep, pte_num);
+}
+
+void huge_ptep_set_wrprotect(struct mm_struct *mm,
+				    unsigned long addr, pte_t *ptep)
+{
+	int i;
+	int pte_num;
+	pte_t pte = READ_ONCE(*ptep);
+
+	if (!pte_napot(pte))
+		return ptep_set_wrprotect(mm, addr, ptep);
+
+	pte_num = napot_pte_num(pte);
+	ptep = huge_pte_offset(mm, addr, NAPOT_CONT64KB_SIZE);
+
+	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++)
+		ptep_set_wrprotect(mm, addr, ptep);
+}
+
+pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+				  unsigned long addr, pte_t *ptep)
+{
+	int pte_num;
+	pte_t pte = READ_ONCE(*ptep);
+
+	if (!pte_napot(pte)) {
+		ptep_clear_flush(vma, addr, ptep);
+		return pte;
+	}
+
+	pte_num = napot_pte_num(pte);
+	clear_flush(vma->vm_mm, addr, ptep, pte_num);
+
+	return pte;
+}
+
+void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
+			   pte_t *ptep, unsigned long sz)
+{
+	int i, pte_num;
+
+	pte_num = napot_pte_num(READ_ONCE(*ptep));
+	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++)
+		pte_clear(mm, addr, ptep);
+}
+
+void riscv_set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
+				 pte_t *ptep, pte_t pte, unsigned long sz)
+{
+	int i, pte_num;
+
+	pte_num = napot_pte_num(READ_ONCE(*ptep));
+
+	for (i = 0; i < pte_num; i++, ptep++)
+		set_pte(ptep, pte);
+}
+#endif /*CONFIG_SVNAPOT*/
+
 int pud_huge(pud_t pud)
 {
 	return pud_leaf(pud);
@@ -18,17 +240,26 @@ bool __init arch_hugetlb_valid_size(unsigned long size)
 		return true;
 	else if (IS_ENABLED(CONFIG_64BIT) && size == PUD_SIZE)
 		return true;
+#ifdef CONFIG_SVNAPOT
+	else if (has_svnapot() && size == NAPOT_CONT64KB_SIZE)
+		return true;
+#endif /*CONFIG_SVNAPOT*/
 	else
 		return false;
 }
 
-#ifdef CONFIG_CONTIG_ALLOC
-static __init int gigantic_pages_init(void)
+static __init int hugetlbpage_init(void)
 {
+#ifdef CONFIG_CONTIG_ALLOC
 	/* With CONTIG_ALLOC, we can allocate gigantic pages at runtime */
 	if (IS_ENABLED(CONFIG_64BIT))
 		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
+#endif /*CONFIG_CONTIG_ALLOC*/
+	hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
+#ifdef CONFIG_SVNAPOT
+	if (has_svnapot())
+		hugetlb_add_hstate(NAPOT_CONT64KB_SHIFT - PAGE_SHIFT);
+#endif /*CONFIG_SVNAPOT*/
 	return 0;
 }
-arch_initcall(gigantic_pages_init);
-#endif
+arch_initcall(hugetlbpage_init);
-- 
2.35.1


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[PATCH v2 4/4] mm: support Svnapot in huge vmap

[panqinglin2020]

From: Qinglin Pan <panqinglin2020@iscas.ac.cn>

The HAVE_ARCH_HUGE_VMAP option can be used to help implement arch
special huge vmap size. This patch selects this option by default and
re-writes the arch_vmap_pte_range_map_size for Svnapot 64KB size.

It can be tested when booting kernel in qemu with pci device, which
will make the kernel to call pci driver using ioremap, and the
re-written function will be called.

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a1fcdd04b12c..35731d627762 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -70,6 +70,7 @@ config RISCV
 	select GENERIC_TIME_VSYSCALL if MMU && 64BIT
 	select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL
 	select HAVE_ARCH_KASAN if MMU && 64BIT
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 34c4be9de79e..75c2cf1f11bd 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -767,6 +767,43 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+
+static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+
+static inline void p4d_clear_huge(p4d_t *p4d) { }
+
+static inline int pud_clear_huge(pud_t *pud)
+{
+	return 0;
+}
+
+static inline int pmd_clear_huge(pmd_t *pmd)
+{
+	return 0;
+}
+
+static inline int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
+{
+	return 0;
+}
+
+static inline int pud_free_pmd_page(pud_t *pud, unsigned long addr)
+{
+	return 0;
+}
+
+static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
+{
+	return 0;
+}
+
 /*
  * Encode and decode a swap entry
  *
diff --git a/arch/riscv/include/asm/vmalloc.h b/arch/riscv/include/asm/vmalloc.h
index ff9abc00d139..776a88bd4fcf 100644
--- a/arch/riscv/include/asm/vmalloc.h
+++ b/arch/riscv/include/asm/vmalloc.h
@@ -1,4 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 #ifndef _ASM_RISCV_VMALLOC_H
 #define _ASM_RISCV_VMALLOC_H
 
+#include <asm/pgtable.h>
+
+#ifdef CONFIG_SVNAPOT
+#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)
+{
+	bool is_napot_addr = !(addr & NAPOT_CONT64KB_MASK);
+	bool pfn_align_napot = !(pfn & (NAPOT_64KB_PTE_NUM - 1UL));
+	bool space_enough = ((end - addr) >= NAPOT_CONT64KB_SIZE);
+
+	if (has_svnapot() && is_napot_addr && pfn_align_napot && space_enough
+			&& max_page_shift >= NAPOT_CONT64KB_SHIFT)
+		return NAPOT_CONT64KB_SIZE;
+
+	return PAGE_SIZE;
+}
+#endif /*CONFIG_SVNAPOT*/
+
 #endif /* _ASM_RISCV_VMALLOC_H */
-- 
2.35.1


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Re: [PATCH v2 1/4] riscv, mm: detect svnapot cpu support at runtime

[Jisheng Zhang]

On Sat, Jul 16, 2022 at 04:56:45PM +0800, panqinglin2020@iscas.ac.cn wrote:
> From: Qinglin Pan <panqinglin2020@iscas.ac.cn>
> 
> This patch add two erratas to enable/disable svnapot support, patches code
> dynamicly when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
> option is set. It will influence the behavior of has_svnapot function and
> pte_pfn function. All code dependent on svnapot should make sure that has_svnapot
> return true firstly.
> 
> Also, this patch modifies PTE definition for Svnapot, and creates some functions in
> pgtable.h to mark a PTE as napot and check if it is a Svnapot PTE.
> Until now, only 64KB napot size is supported in draft spec, so some macros
> has only 64KB version.
> 
> Yours,
> Qinglin

hmm, this "Yours ..." should be removed in commit msg
> 
> Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index b17fd4666b0c..c5e1629a6033 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -385,6 +385,13 @@ config FPU
>  
>  	  If you don't know what to do here, say Y.
>  
> +config SVNAPOT
> +	bool "Svnapot support"

Do we add an config opition for each isa extension? That's not
necessary. I think we'd better remove this CONFIG option and keep
unified Image in mind.

> +	default n
> +	help
> +	  Select if your CPU supports Svnapot and you want to enable it when
> +	  kernel is booting.
> +
>  endmenu # "Platform type"
>  menu "Kernel features"
> diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
> index 9e2888dbb5b1..84ad32075637 100644
> --- a/arch/riscv/include/asm/errata_list.h
> +++ b/arch/riscv/include/asm/errata_list.h
> @@ -20,7 +20,8 @@
>  #endif
>  
>  #define	CPUFEATURE_SVPBMT 0
> -#define	CPUFEATURE_NUMBER 1
> +#define	CPUFEATURE_SVNAPOT 1
> +#define	CPUFEATURE_NUMBER 2
>  
>  #ifdef __ASSEMBLY__
>  
> @@ -93,6 +94,27 @@ asm volatile(ALTERNATIVE(						\
>  #define ALT_THEAD_PMA(_val)
>  #endif
>  
> +#define ALT_SVNAPOT(_val)						\

I believe SVNAPOT can be supported w/o ALTERNATIVE, static key mechanism
would be much simpler.

> +asm(ALTERNATIVE("li %0, 0", "li %0, 1", 0,				\
> +		CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)			\
> +		: "=r"(_val) :)
> +
> +#define ALT_SVNAPOT_PTE_PFN(_val, _napot_shift, _pfn_mask, _pfn_shift)	\
> +asm(ALTERNATIVE("and %0, %1, %2\n\t"					\
> +		"srli %0, %0, %3\n\t"					\
> +		"nop\n\tnop\n\tnop",					\
> +		"srli t3, %1, %4\n\t"					\
> +		"and %0, %1, %2\n\t"					\
> +		"srli %0, %0, %3\n\t"					\
> +		"sub  t4, %0, t3\n\t"					\
> +		"and  %0, %0, t4",					\
> +		0, CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)			\
> +		: "+r"(_val)						\
> +		: "r"(_val),						\
> +		  "r"(_pfn_mask),					\
> +		  "i"(_pfn_shift),					\
> +		  "i"(_napot_shift))
> +
>  #endif /* __ASSEMBLY__ */
>  
>  #endif
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index e48eebdd2631..292ab93321e3 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -54,6 +54,7 @@ extern unsigned long elf_hwcap;
>  enum riscv_isa_ext_id {
>  	RISCV_ISA_EXT_SSCOFPMF = RISCV_ISA_EXT_BASE,
>  	RISCV_ISA_EXT_SVPBMT,
> +	RISCV_ISA_EXT_SVNAPOT,
>  	RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX,
>  };
>  
> diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
> index 5c2aba5efbd0..e8463515a46c 100644
> --- a/arch/riscv/include/asm/pgtable-64.h
> +++ b/arch/riscv/include/asm/pgtable-64.h
> @@ -74,6 +74,20 @@ 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      (1UL << _PAGE_NAPOT_SHIFT)
> +#define NAPOT_CONT64KB_ORDER 4UL
> +#define NAPOT_CONT64KB_SHIFT (NAPOT_CONT64KB_ORDER + PAGE_SHIFT)
> +#define NAPOT_CONT64KB_SIZE (1UL << NAPOT_CONT64KB_SHIFT)
> +#define NAPOT_CONT64KB_MASK (NAPOT_CONT64KB_SIZE - 1)
> +#define NAPOT_64KB_PTE_NUM (1UL << NAPOT_CONT64KB_ORDER)
> +#define NAPOT_64KB_MASK (7UL << _PAGE_PFN_SHIFT)
> +
>  /*
>   * [62:61] Svpbmt Memory Type definitions:
>   *
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 1d1be9d9419c..34c4be9de79e 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -284,10 +284,38 @@ static inline pte_t pud_pte(pud_t pud)
>  	return __pte(pud_val(pud));
>  }
>  
> +static inline bool has_svnapot(void) {
> +	u64 _val;
> +	ALT_SVNAPOT(_val);
> +	return _val;
> +}
> +
> +#ifdef CONFIG_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)
> +{
> +	unsigned long napot_bits = (1UL << (order - 1)) << _PAGE_PFN_SHIFT;
> +	unsigned long lower_prot =
> +		pte_val(pte) & ((1UL << _PAGE_PFN_SHIFT) - 1UL);
> +	unsigned long upper_prot = (pte_val(pte) >> _PAGE_PFN_SHIFT)
> +				   << _PAGE_PFN_SHIFT;
> +
> +	return __pte(upper_prot | napot_bits | lower_prot | _PAGE_NAPOT);
> +}
> +#endif /* CONFIG_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 _val  = pte_val(pte);
> +	ALT_SVNAPOT_PTE_PFN(_val, _PAGE_NAPOT_SHIFT,
> +			_PAGE_PFN_MASK, _PAGE_PFN_SHIFT);
> +	return _val;
>  }
>  
>  #define pte_page(x)     pfn_to_page(pte_pfn(x))
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index fba9e9f46a8c..9f1113fa2b96 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -89,6 +89,7 @@ int riscv_of_parent_hartid(struct device_node *node)
>  static struct riscv_isa_ext_data isa_ext_arr[] = {
>  	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
>  	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> +	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
>  	__RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
>  };
>  
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 1b3ec44e25f5..9f38b7d02f2a 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -198,6 +198,7 @@ void __init riscv_fill_hwcap(void)
>  			} else {
>  				SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
>  				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
> +				SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
>  			}
>  #undef SET_ISA_EXT_MAP
>  		}
> @@ -259,6 +260,20 @@ static bool __init_or_module cpufeature_probe_svpbmt(unsigned int stage)
>  	return false;
>  }
>  
> +static bool __init_or_module cpufeature_probe_svnapot(unsigned int stage)
> +{
> +#ifdef CONFIG_SVNAPOT
> +	switch (stage) {
> +	case RISCV_ALTERNATIVES_EARLY_BOOT:
> +		return false;
> +	default:
> +		return riscv_isa_extension_available(NULL, SVNAPOT);
> +	}
> +#endif
> +
> +	return false;
> +}
> +
>  /*
>   * Probe presence of individual extensions.
>   *
> @@ -273,6 +288,9 @@ static u32 __init_or_module cpufeature_probe(unsigned int stage)
>  	if (cpufeature_probe_svpbmt(stage))
>  		cpu_req_feature |= (1U << CPUFEATURE_SVPBMT);
>  
> +	if (cpufeature_probe_svnapot(stage))
> +		cpu_req_feature |= (1U << CPUFEATURE_SVNAPOT);
> +
>  	return cpu_req_feature;
>  }
>  
> -- 
> 2.35.1
> 
> 
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Re: [PATCH v2 1/4] riscv, mm: detect svnapot cpu support at runtime

[Conor.Dooley]

On 16/07/2022 13:35, Jisheng Zhang wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Sat, Jul 16, 2022 at 04:56:45PM +0800, panqinglin2020@iscas.ac.cn wrote:
>> From: Qinglin Pan <panqinglin2020@iscas.ac.cn>
>>
>> This patch add two erratas to enable/disable svnapot support, patches code
>> dynamicly when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
>> option is set. It will influence the behavior of has_svnapot function and
>> pte_pfn function. All code dependent on svnapot should make sure that has_svnapot
>> return true firstly.
>>
>> Also, this patch modifies PTE definition for Svnapot, and creates some functions in
>> pgtable.h to mark a PTE as napot and check if it is a Svnapot PTE.
>> Until now, only 64KB napot size is supported in draft spec, so some macros
>> has only 64KB version.
>>
>> Yours,
>> Qinglin
> 
> hmm, this "Yours ..." should be removed in commit msg

And while they're at it, they can drop the "This patch".

I might've said this on a v1 (I know I said it on someone's
v1 recently) that having "Also, this patch" makes it sound
like this should actually be two patches and not one.

Thanks,
Conor.

>>
>> Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index b17fd4666b0c..c5e1629a6033 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -385,6 +385,13 @@ config FPU
>>
>>         If you don't know what to do here, say Y.
>>
>> +config SVNAPOT
>> +     bool "Svnapot support"
> 
> Do we add an config opition for each isa extension? That's not
> necessary. I think we'd better remove this CONFIG option and keep
> unified Image in mind.
> 
>> +     default n
>> +     help
>> +       Select if your CPU supports Svnapot and you want to enable it when
>> +       kernel is booting.
>> +
>>  endmenu # "Platform type"
>>  menu "Kernel features"
>> diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
>> index 9e2888dbb5b1..84ad32075637 100644
>> --- a/arch/riscv/include/asm/errata_list.h
>> +++ b/arch/riscv/include/asm/errata_list.h
>> @@ -20,7 +20,8 @@
>>  #endif
>>
>>  #define      CPUFEATURE_SVPBMT 0
>> -#define      CPUFEATURE_NUMBER 1
>> +#define      CPUFEATURE_SVNAPOT 1
>> +#define      CPUFEATURE_NUMBER 2
>>
>>  #ifdef __ASSEMBLY__
>>
>> @@ -93,6 +94,27 @@ asm volatile(ALTERNATIVE(                                          \
>>  #define ALT_THEAD_PMA(_val)
>>  #endif
>>
>> +#define ALT_SVNAPOT(_val)                                            \
> 
> I believe SVNAPOT can be supported w/o ALTERNATIVE, static key mechanism
> would be much simpler.
> 
>> +asm(ALTERNATIVE("li %0, 0", "li %0, 1", 0,                           \
>> +             CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)                     \
>> +             : "=r"(_val) :)
>> +
>> +#define ALT_SVNAPOT_PTE_PFN(_val, _napot_shift, _pfn_mask, _pfn_shift)       \
>> +asm(ALTERNATIVE("and %0, %1, %2\n\t"                                 \
>> +             "srli %0, %0, %3\n\t"                                   \
>> +             "nop\n\tnop\n\tnop",                                    \
>> +             "srli t3, %1, %4\n\t"                                   \
>> +             "and %0, %1, %2\n\t"                                    \
>> +             "srli %0, %0, %3\n\t"                                   \
>> +             "sub  t4, %0, t3\n\t"                                   \
>> +             "and  %0, %0, t4",                                      \
>> +             0, CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)                  \
>> +             : "+r"(_val)                                            \
>> +             : "r"(_val),                                            \
>> +               "r"(_pfn_mask),                                       \
>> +               "i"(_pfn_shift),                                      \
>> +               "i"(_napot_shift))
>> +
>>  #endif /* __ASSEMBLY__ */
>>
>>  #endif
>> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
>> index e48eebdd2631..292ab93321e3 100644
>> --- a/arch/riscv/include/asm/hwcap.h
>> +++ b/arch/riscv/include/asm/hwcap.h
>> @@ -54,6 +54,7 @@ extern unsigned long elf_hwcap;
>>  enum riscv_isa_ext_id {
>>       RISCV_ISA_EXT_SSCOFPMF = RISCV_ISA_EXT_BASE,
>>       RISCV_ISA_EXT_SVPBMT,
>> +     RISCV_ISA_EXT_SVNAPOT,
>>       RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX,
>>  };
>>
>> diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
>> index 5c2aba5efbd0..e8463515a46c 100644
>> --- a/arch/riscv/include/asm/pgtable-64.h
>> +++ b/arch/riscv/include/asm/pgtable-64.h
>> @@ -74,6 +74,20 @@ 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      (1UL << _PAGE_NAPOT_SHIFT)
>> +#define NAPOT_CONT64KB_ORDER 4UL
>> +#define NAPOT_CONT64KB_SHIFT (NAPOT_CONT64KB_ORDER + PAGE_SHIFT)
>> +#define NAPOT_CONT64KB_SIZE (1UL << NAPOT_CONT64KB_SHIFT)
>> +#define NAPOT_CONT64KB_MASK (NAPOT_CONT64KB_SIZE - 1)
>> +#define NAPOT_64KB_PTE_NUM (1UL << NAPOT_CONT64KB_ORDER)
>> +#define NAPOT_64KB_MASK (7UL << _PAGE_PFN_SHIFT)
>> +
>>  /*
>>   * [62:61] Svpbmt Memory Type definitions:
>>   *
>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> index 1d1be9d9419c..34c4be9de79e 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -284,10 +284,38 @@ static inline pte_t pud_pte(pud_t pud)
>>       return __pte(pud_val(pud));
>>  }
>>
>> +static inline bool has_svnapot(void) {
>> +     u64 _val;
>> +     ALT_SVNAPOT(_val);
>> +     return _val;
>> +}
>> +
>> +#ifdef CONFIG_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)
>> +{
>> +     unsigned long napot_bits = (1UL << (order - 1)) << _PAGE_PFN_SHIFT;
>> +     unsigned long lower_prot =
>> +             pte_val(pte) & ((1UL << _PAGE_PFN_SHIFT) - 1UL);
>> +     unsigned long upper_prot = (pte_val(pte) >> _PAGE_PFN_SHIFT)
>> +                                << _PAGE_PFN_SHIFT;
>> +
>> +     return __pte(upper_prot | napot_bits | lower_prot | _PAGE_NAPOT);
>> +}
>> +#endif /* CONFIG_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 _val  = pte_val(pte);
>> +     ALT_SVNAPOT_PTE_PFN(_val, _PAGE_NAPOT_SHIFT,
>> +                     _PAGE_PFN_MASK, _PAGE_PFN_SHIFT);
>> +     return _val;
>>  }
>>
>>  #define pte_page(x)     pfn_to_page(pte_pfn(x))
>> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
>> index fba9e9f46a8c..9f1113fa2b96 100644
>> --- a/arch/riscv/kernel/cpu.c
>> +++ b/arch/riscv/kernel/cpu.c
>> @@ -89,6 +89,7 @@ int riscv_of_parent_hartid(struct device_node *node)
>>  static struct riscv_isa_ext_data isa_ext_arr[] = {
>>       __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
>>       __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
>> +     __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
>>       __RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
>>  };
>>
>> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
>> index 1b3ec44e25f5..9f38b7d02f2a 100644
>> --- a/arch/riscv/kernel/cpufeature.c
>> +++ b/arch/riscv/kernel/cpufeature.c
>> @@ -198,6 +198,7 @@ void __init riscv_fill_hwcap(void)
>>                       } else {
>>                               SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
>>                               SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
>> +                             SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
>>                       }
>>  #undef SET_ISA_EXT_MAP
>>               }
>> @@ -259,6 +260,20 @@ static bool __init_or_module cpufeature_probe_svpbmt(unsigned int stage)
>>       return false;
>>  }
>>
>> +static bool __init_or_module cpufeature_probe_svnapot(unsigned int stage)
>> +{
>> +#ifdef CONFIG_SVNAPOT
>> +     switch (stage) {
>> +     case RISCV_ALTERNATIVES_EARLY_BOOT:
>> +             return false;
>> +     default:
>> +             return riscv_isa_extension_available(NULL, SVNAPOT);
>> +     }
>> +#endif
>> +
>> +     return false;
>> +}
>> +
>>  /*
>>   * Probe presence of individual extensions.
>>   *
>> @@ -273,6 +288,9 @@ static u32 __init_or_module cpufeature_probe(unsigned int stage)
>>       if (cpufeature_probe_svpbmt(stage))
>>               cpu_req_feature |= (1U << CPUFEATURE_SVPBMT);
>>
>> +     if (cpufeature_probe_svnapot(stage))
>> +             cpu_req_feature |= (1U << CPUFEATURE_SVNAPOT);
>> +
>>       return cpu_req_feature;
>>  }
>>
>> --
>> 2.35.1
>>
>>
>> _______________________________________________
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>> linux-riscv@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-riscv
> 
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Re: Re: [PATCH v2 1/4] riscv, mm: detect svnapot cpu support at runtime

[潘庆霖]

> On 16/07/2022 13:35, Jisheng Zhang wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On Sat, Jul 16, 2022 at 04:56:45PM +0800, panqinglin2020@iscas.ac.cn wrote:
&gt; &gt;&gt; From: Qinglin Pan <panqinglin2020@iscas.ac.cn>
&gt; &gt;&gt;
&gt; &gt;&gt; This patch add two erratas to enable/disable svnapot support, patches code
&gt; &gt;&gt; dynamicly when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
&gt; &gt;&gt; option is set. It will influence the behavior of has_svnapot function and
&gt; &gt;&gt; pte_pfn function. All code dependent on svnapot should make sure that has_svnapot
&gt; &gt;&gt; return true firstly.
&gt; &gt;&gt;
&gt; &gt;&gt; Also, this patch modifies PTE definition for Svnapot, and creates some functions in
&gt; &gt;&gt; pgtable.h to mark a PTE as napot and check if it is a Svnapot PTE.
&gt; &gt;&gt; Until now, only 64KB napot size is supported in draft spec, so some macros
&gt; &gt;&gt; has only 64KB version.
&gt; &gt;&gt;
&gt; &gt;&gt; Yours,
&gt; &gt;&gt; Qinglin
&gt; &gt; 
&gt; &gt; hmm, this "Yours ..." should be removed in commit msg
&gt; 
&gt; And while they're at it, they can drop the "This patch".
&gt; 
&gt; I might've said this on a v1 (I know I said it on someone's
&gt; v1 recently) that having "Also, this patch" makes it sound
&gt; like this should actually be two patches and not one.
&gt; 
&gt; Thanks,
&gt; Conor.
&gt; 

Thanks for the hints, will do in a newer version patch.


Thanks,
Qinglin.</panqinglin2020@iscas.ac.cn>
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Re: Re: [PATCH v2 1/4] riscv, mm: detect svnapot cpu support at runtime

[潘庆霖]

> >  
> > +config SVNAPOT
> > + bool "Svnapot support"
> 
> Do we add an config opition for each isa extension? That's not
> necessary. I think we'd better remove this CONFIG option and keep
> unified Image in mind.
> 

I am also not very sure about necessity of this. Maybe we should allow user to disable
Svnapot support manually? As this support may introduce extra overhead in functions
like pte_pfn. So should such option be reserved for setting it off manually? If it should not,
I will remove it in a newer version.

> > diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
> > index 9e2888dbb5b1..84ad32075637 100644
> > --- a/arch/riscv/include/asm/errata_list.h
> > +++ b/arch/riscv/include/asm/errata_list.h
> > @@ -20,7 +20,8 @@
> >  #endif
> >  
> >  #define CPUFEATURE_SVPBMT 0
> > -#define CPUFEATURE_NUMBER 1
> > +#define CPUFEATURE_SVNAPOT 1
> > +#define CPUFEATURE_NUMBER 2
> >  
> >  #ifdef __ASSEMBLY__
> >  
> > @@ -93,6 +94,27 @@ asm volatile(ALTERNATIVE(      \
> >  #define ALT_THEAD_PMA(_val)
> >  #endif
> >  
> > +#define ALT_SVNAPOT(_val)      \
> 
> I believe SVNAPOT can be supported w/o ALTERNATIVE, static key mechanism
> would be much simpler.
>

Thanks for the hint, will implement it with static key mechanism in a newer version.

Thanks,
Qinglin

> > +asm(ALTERNATIVE("li %0, 0", "li %0, 1", 0,    \
> > +  CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)   \
> > +  : "=r"(_val) :)
> > +
> > +#define ALT_SVNAPOT_PTE_PFN(_val, _napot_shift, _pfn_mask, _pfn_shift) \
> > +asm(ALTERNATIVE("and %0, %1, %2\n\t"     \
> > +  "srli %0, %0, %3\n\t"     \
> > +  "nop\n\tnop\n\tnop",     \
> > +  "srli t3, %1, %4\n\t"     \
> > +  "and %0, %1, %2\n\t"     \
> > +  "srli %0, %0, %3\n\t"     \
> > +  "sub  t4, %0, t3\n\t"     \
> > +  "and  %0, %0, t4",     \
> > +  0, CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT)   \
> > +  : "+r"(_val)      \
> > +  : "r"(_val),      \
> > +    "r"(_pfn_mask),     \
> > +    "i"(_pfn_shift),     \
> > +    "i"(_napot_shift))
> > +
> >  #endif /* __ASSEMBLY__ */
> >  
> >  #endif


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Re: [PATCH v2 1/4] riscv, mm: detect svnapot cpu support at runtime

[Conor.Dooley]

On 16/07/2022 14:41, 潘庆霖 wrote:
> > On 16/07/2022 13:35, Jisheng Zhang wrote:
> > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > > 
> > > On Sat, Jul 16, 2022 at 04:56:45PM +0800, panqinglin2020@iscas.ac.cn wrote:
> &gt; &gt;&gt; From: Qinglin Pan <panqinglin2020@iscas.ac.cn>
> &gt; &gt;&gt;
> &gt; &gt;&gt; This patch add two erratas to enable/disable svnapot support, patches code
> &gt; &gt;&gt; dynamicly when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
> &gt; &gt;&gt; option is set. It will influence the behavior of has_svnapot function and
> &gt; &gt;&gt; pte_pfn function. All code dependent on svnapot should make sure that has_svnapot
> &gt; &gt;&gt; return true firstly.
> &gt; &gt;&gt;
> &gt; &gt;&gt; Also, this patch modifies PTE definition for Svnapot, and creates some functions in
> &gt; &gt;&gt; pgtable.h to mark a PTE as napot and check if it is a Svnapot PTE.
> &gt; &gt;&gt; Until now, only 64KB napot size is supported in draft spec, so some macros
> &gt; &gt;&gt; has only 64KB version.
> &gt; &gt;&gt;
> &gt; &gt;&gt; Yours,
> &gt; &gt;&gt; Qinglin
> &gt; &gt; 
> &gt; &gt; hmm, this "Yours ..." should be removed in commit msg
> &gt; 
> &gt; And while they're at it, they can drop the "This patch".
> &gt; 
> &gt; I might've said this on a v1 (I know I said it on someone's
> &gt; v1 recently) that having "Also, this patch" makes it sound
> &gt; like this should actually be two patches and not one.
> &gt; 
> &gt; Thanks,
> &gt; Conor.
> &gt;

^ might want to fix your mail client to not do that too! :)
Thanks,
Conor

> 
> Thanks for the hints, will do in a newer version patch.
> 
> 
> Thanks,
> Qinglin.</panqinglin2020@iscas.ac.cn>
> _______________________________________________
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