[RFC PATCH v2 02/21] riscv: mm: Configure satp with hw page pfn

[Xu Lu <luxu.kernel@bytedance.com>]

The control register CSR_SATP on RISC-V, which points to the root page
table page, is used by MMU to translate va to pa when TLB miss happens.
Thus it should be encoded at a granularity of hardware page, while
existing code usually encodes it via software page frame number.

This commit corrects encoding operations of CSR_SATP register. To get
developers rid of the annoying encoding format of CSR_SATP and the
conversion between sw pfn and hw pfn, we abstract the encoding
operations of CSR_SATP into a specific function.

Signed-off-by: Xu Lu <luxu.kernel@bytedance.com>
---
 arch/riscv/include/asm/pgtable.h | 14 ++++++++++++++
 arch/riscv/kernel/head.S         |  4 ++--
 arch/riscv/kernel/hibernate.c    |  3 ++-
 arch/riscv/mm/context.c          |  7 +++----
 arch/riscv/mm/fault.c            |  2 +-
 arch/riscv/mm/init.c             |  7 +++++--
 arch/riscv/mm/kasan_init.c       |  7 +++++--
 7 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 9d6d0ff86c76..9d3947ec3523 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -206,6 +206,20 @@ extern pgd_t swapper_pg_dir[];
 extern pgd_t trampoline_pg_dir[];
 extern pgd_t early_pg_dir[];
 
+static inline unsigned long make_satp(unsigned long pfn,
+		unsigned long asid, unsigned long satp_mode)
+{
+	return (pfn_to_hwpfn(pfn) |
+		((asid & SATP_ASID_MASK) << SATP_ASID_SHIFT) | satp_mode);
+}
+
+static inline unsigned long satp_pfn(unsigned long satp)
+{
+	unsigned long hwpfn = satp & SATP_PPN;
+
+	return hwpfn_to_pfn(hwpfn);
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static inline int pmd_present(pmd_t pmd)
 {
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 356d5397b2a2..b8568e3ddefa 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -86,7 +86,7 @@ relocate_enable_mmu:
 	csrw CSR_TVEC, a2
 
 	/* Compute satp for kernel page tables, but don't load it yet */
-	srl a2, a0, PAGE_SHIFT
+	srl a2, a0, HW_PAGE_SHIFT
 	la a1, satp_mode
 	XIP_FIXUP_OFFSET a1
 	REG_L a1, 0(a1)
@@ -100,7 +100,7 @@ relocate_enable_mmu:
 	 */
 	la a0, trampoline_pg_dir
 	XIP_FIXUP_OFFSET a0
-	srl a0, a0, PAGE_SHIFT
+	srl a0, a0, HW_PAGE_SHIFT
 	or a0, a0, a1
 	sfence.vma
 	csrw CSR_SATP, a0
diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
index 671b686c0158..155be6b1d32c 100644
--- a/arch/riscv/kernel/hibernate.c
+++ b/arch/riscv/kernel/hibernate.c
@@ -395,7 +395,8 @@ int swsusp_arch_resume(void)
 	if (ret)
 		return ret;
 
-	hibernate_restore_image(resume_hdr.saved_satp, (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
+	hibernate_restore_image(resume_hdr.saved_satp,
+				make_satp(PFN_DOWN(__pa(resume_pg_dir)), 0, satp_mode),
 				resume_hdr.restore_cpu_addr);
 
 	return 0;
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index 4abe3de23225..229c78d9ad3a 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -189,9 +189,8 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)
 	raw_spin_unlock_irqrestore(&context_lock, flags);
 
 switch_mm_fast:
-	csr_write(CSR_SATP, virt_to_pfn(mm->pgd) |
-		  (cntx2asid(cntx) << SATP_ASID_SHIFT) |
-		  satp_mode);
+	csr_write(CSR_SATP, make_satp(virt_to_pfn(mm->pgd), cntx2asid(cntx),
+				      satp_mode));
 
 	if (need_flush_tlb)
 		local_flush_tlb_all();
@@ -200,7 +199,7 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)
 static void set_mm_noasid(struct mm_struct *mm)
 {
 	/* Switch the page table and blindly nuke entire local TLB */
-	csr_write(CSR_SATP, virt_to_pfn(mm->pgd) | satp_mode);
+	csr_write(CSR_SATP, make_satp(virt_to_pfn(mm->pgd), 0, satp_mode));
 	local_flush_tlb_all_asid(0);
 }
 
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index a9f2b4af8f3f..4772152be0f9 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -133,7 +133,7 @@ static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long a
 	 * of a task switch.
 	 */
 	index = pgd_index(addr);
-	pfn = csr_read(CSR_SATP) & SATP_PPN;
+	pfn = satp_pfn(csr_read(CSR_SATP));
 	pgd = (pgd_t *)pfn_to_virt(pfn) + index;
 	pgd_k = init_mm.pgd + index;
 
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 0e8c20adcd98..f9334aab45a6 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -836,7 +836,7 @@ static __init void set_satp_mode(uintptr_t dtb_pa)
 				(uintptr_t)early_p4d : (uintptr_t)early_pud,
 			   PGDIR_SIZE, PAGE_TABLE);
 
-	identity_satp = PFN_DOWN((uintptr_t)&early_pg_dir) | satp_mode;
+	identity_satp = make_satp(PFN_DOWN((uintptr_t)&early_pg_dir), 0, satp_mode);
 
 	local_flush_tlb_all();
 	csr_write(CSR_SATP, identity_satp);
@@ -1316,6 +1316,8 @@ static void __init create_linear_mapping_page_table(void)
 
 static void __init setup_vm_final(void)
 {
+	unsigned long satp;
+
 	/* Setup swapper PGD for fixmap */
 #if !defined(CONFIG_64BIT)
 	/*
@@ -1349,7 +1351,8 @@ static void __init setup_vm_final(void)
 	clear_fixmap(FIX_P4D);
 
 	/* Move to swapper page table */
-	csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | satp_mode);
+	satp = make_satp(PFN_DOWN(__pa_symbol(swapper_pg_dir)), 0, satp_mode);
+	csr_write(CSR_SATP, satp);
 	local_flush_tlb_all();
 
 	pt_ops_set_late();
diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index c301c8d291d2..3eee1665358e 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -482,11 +482,13 @@ static void __init create_tmp_mapping(void)
 
 void __init kasan_init(void)
 {
+	unsigned long satp;
 	phys_addr_t p_start, p_end;
 	u64 i;
 
 	create_tmp_mapping();
-	csr_write(CSR_SATP, PFN_DOWN(__pa(tmp_pg_dir)) | satp_mode);
+	satp = make_satp(PFN_DOWN(__pa(tmp_pg_dir)), 0, satp_mode);
+	csr_write(CSR_SATP, satp);
 
 	kasan_early_clear_pgd(pgd_offset_k(KASAN_SHADOW_START),
 			      KASAN_SHADOW_START, KASAN_SHADOW_END);
@@ -531,6 +533,7 @@ void __init kasan_init(void)
 	memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
 	init_task.kasan_depth = 0;
 
-	csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
+	satp = make_satp(PFN_DOWN(__pa(swapper_pg_dir)), 0, satp_mode);
+	csr_write(CSR_SATP, satp);
 	local_flush_tlb_all();
 }
-- 
2.20.1


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