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From:   Xu Lu <luxu.kernel@bytedance.com>
To:     paul.walmsley@sifive.com, palmer@dabbelt.com,
        aou@eecs.berkeley.edu, ardb@kernel.org, anup@brainfault.org,
        atishp@atishpatra.org
Cc:     dengliang.1214@bytedance.com, xieyongji@bytedance.com,
        lihangjing@bytedance.com, songmuchun@bytedance.com,
        punit.agrawal@bytedance.com, linux-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org, Xu Lu <luxu.kernel@bytedance.com>
Subject: [RFC PATCH V1 07/11] riscv: Adapt satp operations to gap between hw page and sw page
Date:   Thu, 23 Nov 2023 14:57:04 +0800
Message-Id: <20231123065708.91345-8-luxu.kernel@bytedance.com>
In-Reply-To: <20231123065708.91345-1-luxu.kernel@bytedance.com>
References: <20231123065708.91345-1-luxu.kernel@bytedance.com>
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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 | 7 +++++++
 arch/riscv/kernel/head.S         | 4 ++--
 arch/riscv/kernel/hibernate.c    | 3 ++-
 arch/riscv/mm/context.c          | 7 +++----
 arch/riscv/mm/fault.c            | 1 +
 arch/riscv/mm/init.c             | 7 +++++--
 arch/riscv/mm/kasan_init.c       | 7 +++++--
 7 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 9f81fe046cb8..56366f07985d 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -213,6 +213,13 @@ 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 __always_inline int __pte_present(unsigned long pteval)
 {
 	return (pteval & (_PAGE_PRESENT | _PAGE_PROT_NONE));
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index b77397432403..dace2e4e6164 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -87,7 +87,7 @@ 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
 	REG_L a1, 0(a1)
 	or a2, a2, 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 217fd4de6134..2ecf87433dfc 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -190,9 +190,8 @@ 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) |
-		  ((cntx & asid_mask) << SATP_ASID_SHIFT) |
-		  satp_mode);
+	csr_write(CSR_SATP, make_satp(virt_to_pfn(mm->pgd), (cntx & asid_mask),
+				      satp_mode));
 
 	if (need_flush_tlb)
 		local_flush_tlb_all();
@@ -201,7 +200,7 @@ 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();
 }
 
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 90d4ba36d1d0..026ac007febf 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -133,6 +133,7 @@ static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long a
 	 */
 	index = pgd_index(addr);
 	pfn = csr_read(CSR_SATP) & SATP_PPN;
+	pfn = hwpfn_to_pfn(pfn);
 	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 a768b2b3ff05..c33a90d0c51d 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -805,7 +805,7 @@ 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);
@@ -1285,6 +1285,8 @@ 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)
 	/*
@@ -1318,7 +1320,8 @@ 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 5e39dcf23fdb..72269e9f1964 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -471,11 +471,13 @@ 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);
@@ -520,6 +522,7 @@ 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