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([218.194.32.52]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38f7f292b06sm161141a91.10.2026.07.28.09.15.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jul 2026 09:15:30 -0700 (PDT) From: "Dylan.Wu" To: paul.walmsley@sifive.com, pjw@kernel.org Cc: palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, anup@brainfault.org, atish.patra@linux.dev, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, "Dylan.Wu" , Quan Zhou Subject: [PATCH v3 3/3] KVM: riscv: Register ptdump with debugfs on guest creation Date: Tue, 28 Jul 2026 12:14:49 -0400 Message-Id: <20260728161449.190058-4-fredwudi0305@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260728161449.190058-1-fredwudi0305@gmail.com> References: <3bb2f519-c70b-6c35-c404-6fbfe8adbeb1@kernel.org> <20260728161449.190058-1-fredwudi0305@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Implement the gstage page table dumper for RISC-V KVM, which exposes the guest's gstage page tables via debugfs. When CONFIG_PTDUMP_GSTAGE_DEBUGFS is enabled, a "gstage_page_tables" file will be created under each VM's debugfs directory. This reuses the ptdump framework from the kernel page table dumper, with gstage-specific attribute bits and level definitions. Assisted-by: YuanSheng: deepseek-v4-pro Co-developed-by: Quan Zhou Signed-off-by: Quan Zhou Signed-off-by: Dylan.Wu --- arch/riscv/kvm/Kconfig | 12 +++ arch/riscv/kvm/Makefile | 1 + arch/riscv/kvm/ptdump.c | 177 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 190 insertions(+) create mode 100644 arch/riscv/kvm/ptdump.c diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig index ec2cee0a3..6d62b967f 100644 --- a/arch/riscv/kvm/Kconfig +++ b/arch/riscv/kvm/Kconfig @@ -37,4 +37,16 @@ config KVM If unsure, say N. +config PTDUMP_GSTAGE_DEBUGFS + bool "Present the gstage pagetables to debugfs" + depends on KVM && DEBUG_KERNEL && DEBUG_FS && PTDUMP_DEBUGFS + default n + help + Say Y here if you want to show the RISC-V KVM gstage guest + page tables in debugfs under each VM's debugfs directory as + a file named "gstage_page_tables". This allows inspection of + the second-stage address translation setup for each guest. + + If unsure, say N. + endif # VIRTUALIZATION diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile index 296c2ba05..905593d6f 100644 --- a/arch/riscv/kvm/Makefile +++ b/arch/riscv/kvm/Makefile @@ -19,6 +19,7 @@ kvm-y += isa.o kvm-y += main.o kvm-y += mmu.o kvm-y += nacl.o +kvm-$(CONFIG_PTDUMP_GSTAGE_DEBUGFS) += ptdump.o kvm-y += tlb.o kvm-y += vcpu.o kvm-y += vcpu_config.o diff --git a/arch/riscv/kvm/ptdump.c b/arch/riscv/kvm/ptdump.c new file mode 100644 index 000000000..f436ad48c --- /dev/null +++ b/arch/riscv/kvm/ptdump.c @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 SiFive + */ + +#include +#include +#include + +#include +#include +#include +#include + +enum gstage_address_markers_idx { + GSTAGE_GPA_START_NR, + GSTAGE_GPA_END_NR, + END_OF_GSTAGE_SPACE_NR +}; + +static const struct ptdump_prot_bits gstage_pte_bits[] = { + { + .mask = _PAGE_DIRTY, + .set = "D", + .clear = ".", + }, { + .mask = _PAGE_ACCESSED, + .set = "A", + .clear = ".", + }, { + .mask = _PAGE_GLOBAL, + .set = "G", + .clear = ".", + }, { + .mask = _PAGE_USER, + .set = "U", + .clear = ".", + }, { + .mask = _PAGE_EXEC, + .set = "X", + .clear = ".", + }, { + .mask = _PAGE_WRITE, + .set = "W", + .clear = ".", + }, { + .mask = _PAGE_READ, + .set = "R", + .clear = ".", + }, { + .mask = _PAGE_PRESENT, + .set = "V", + .clear = ".", + } +}; + +static struct ptdump_pg_level gstage_pg_levels[] = { + { /* pgd */ + .bits = gstage_pte_bits, + .num = ARRAY_SIZE(gstage_pte_bits), + .name = "PGD", + }, { /* p4d */ + .bits = gstage_pte_bits, + .num = ARRAY_SIZE(gstage_pte_bits), + .name = "P4D", + }, { /* pud */ + .bits = gstage_pte_bits, + .num = ARRAY_SIZE(gstage_pte_bits), + .name = "PUD", + }, { /* pmd */ + .bits = gstage_pte_bits, + .num = ARRAY_SIZE(gstage_pte_bits), + .name = "PMD", + }, { /* pte */ + .bits = gstage_pte_bits, + .num = ARRAY_SIZE(gstage_pte_bits), + .name = "PTE", + }, +}; + +static void gstage_note_page(struct ptdump_state *pt_st, unsigned long addr, + int level, u64 val) +{ + struct ptdump_pg_state *st = container_of(pt_st, struct ptdump_pg_state, ptdump); + + note_page(pt_st, addr, level, val); + + if (level >= 0) + st->current_prot = val & gstage_pg_levels[level].mask; +} + +static void gstage_note_page_pte(struct ptdump_state *pt_st, unsigned long addr, pte_t pte) +{ + gstage_note_page(pt_st, addr, 4, pte_val(pte)); +} + +static void gstage_note_page_pmd(struct ptdump_state *pt_st, unsigned long addr, pmd_t pmd) +{ + gstage_note_page(pt_st, addr, 3, pmd_val(pmd)); +} + +static void gstage_note_page_pud(struct ptdump_state *pt_st, unsigned long addr, pud_t pud) +{ + gstage_note_page(pt_st, addr, 2, pud_val(pud)); +} + +static void gstage_note_page_p4d(struct ptdump_state *pt_st, unsigned long addr, p4d_t p4d) +{ + gstage_note_page(pt_st, addr, 1, p4d_val(p4d)); +} + +static void gstage_note_page_pgd(struct ptdump_state *pt_st, unsigned long addr, pgd_t pgd) +{ + gstage_note_page(pt_st, addr, 0, pgd_val(pgd)); +} + +static void gstage_note_page_flush(struct ptdump_state *pt_st) +{ + pte_t pte_zero = {0}; + + gstage_note_page(pt_st, 0, -1, pte_val(pte_zero)); +} + +static int gstage_ptdump_show(struct seq_file *m, void *v) +{ + struct kvm *kvm = m->private; + gpa_t gpa_size = kvm_riscv_gstage_gpa_size(kvm->arch.pgd_levels); + struct addr_marker gpa_markers[] = { + [GSTAGE_GPA_START_NR] = { 0, "Guest Physical Address Start" }, + [GSTAGE_GPA_END_NR] = { gpa_size - 1, "Guest Physical Address End" }, + [END_OF_GSTAGE_SPACE_NR] = { -1, NULL }, + }; + struct ptdump_pg_state st = { + .seq = m, + .marker = gpa_markers, + .level = -1, + .pg_level = gstage_pg_levels, + .ptdump = { + .note_page_pte = gstage_note_page_pte, + .note_page_pmd = gstage_note_page_pmd, + .note_page_pud = gstage_note_page_pud, + .note_page_p4d = gstage_note_page_p4d, + .note_page_pgd = gstage_note_page_pgd, + .note_page_flush = gstage_note_page_flush, + .range = (struct ptdump_range[]) { + {0, gpa_size - 1}, + {0, 0} + } + } + }; + unsigned int i, j; + + for (i = 0; i < ARRAY_SIZE(gstage_pg_levels); i++) { + gstage_pg_levels[i].mask = 0; + for (j = 0; j < ARRAY_SIZE(gstage_pte_bits); j++) + gstage_pg_levels[i].mask |= gstage_pte_bits[j].mask; + } + + if (kvm->arch.pgd_levels < 5) + gstage_pg_levels[1].name = "PGD"; + if (kvm->arch.pgd_levels < 4) + gstage_pg_levels[2].name = "PGD"; + if (kvm->arch.pgd_levels < 3) + gstage_pg_levels[3].name = "PGD"; + + ptdump_walk_pgd(&st.ptdump, kvm->mm, kvm->arch.pgd); + + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(gstage_ptdump); + +void kvm_arch_create_vm_debugfs(struct kvm *kvm) +{ + debugfs_create_file("gstage_page_tables", 0400, + kvm->debugfs_dentry, kvm, &gstage_ptdump_fops); +} -- 2.34.1