On 9/9/25 10:25 AM, LIU Zhiwei wrote:
This patch introduces the core implementation for the Memory Protection Table
(MPT) walk, which is the central mechanism of the SMMPT extension.
A new file, `riscv_smmpt.c`, is added to encapsulate the MPT logic. It
implements the `smmpt_lookup()` function, which performs a multi-level
page table-like walk starting from the physical address specified in the
`mptppn` CSR field. This walk determines the access permissions (read,
write, execute) for a given physical address.
The implementation supports various SMMPT modes (SMMTT34, SMMTT43, etc.) and
correctly handles leaf and non-leaf entries, including reserved bit
checks. Helper functions for parsing MPT entries and converting access
permissions are also included in the new `riscv_smmpt.h` header.
Co-authored-by: Huang Tao <eric.hu...@linux.alibaba.com>
Co-authored-by: TANG Tiancheng <lyn...@linux.alibaba.com>
Signed-off-by: LIU Zhiwei <zhiwei_...@linux.alibaba.com>
---
target/riscv/meson.build | 1 +
target/riscv/pmp.h | 3 +
target/riscv/riscv_smmpt.c | 273 +++++++++++++++++++++++++++++++++++++
target/riscv/riscv_smmpt.h | 38 ++++++
4 files changed, 315 insertions(+)
create mode 100644 target/riscv/riscv_smmpt.c
create mode 100644 target/riscv/riscv_smmpt.h
diff --git a/target/riscv/meson.build b/target/riscv/meson.build
index a4bd61e52a..e85b534a64 100644
--- a/target/riscv/meson.build
+++ b/target/riscv/meson.build
@@ -29,6 +29,7 @@ riscv_system_ss = ss.source_set()
riscv_system_ss.add(files(
'arch_dump.c',
'pmp.c',
+ 'riscv_smmpt.c',
'debug.c',
'monitor.c',
'machine.c',
diff --git a/target/riscv/pmp.h b/target/riscv/pmp.h
index 271cf24169..d9c5e74345 100644
--- a/target/riscv/pmp.h
+++ b/target/riscv/pmp.h
@@ -85,6 +85,9 @@ void pmp_update_rule_nums(CPURISCVState *env);
uint32_t pmp_get_num_rules(CPURISCVState *env);
int pmp_priv_to_page_prot(pmp_priv_t pmp_priv);
void pmp_unlock_entries(CPURISCVState *env);
+int get_physical_address_pmp(CPURISCVState *env, int *prot, hwaddr addr,
+ int size, MMUAccessType access_type,
+ int mode);
#define MSECCFG_MML_ISSET(env) get_field(env->mseccfg, MSECCFG_MML)
#define MSECCFG_MMWP_ISSET(env) get_field(env->mseccfg, MSECCFG_MMWP)
diff --git a/target/riscv/riscv_smmpt.c b/target/riscv/riscv_smmpt.c
new file mode 100644
index 0000000000..09e3c66c7f
--- /dev/null
+++ b/target/riscv/riscv_smmpt.c
@@ -0,0 +1,273 @@
+/*
+ * QEMU RISC-V Smmpt (Memory Protection Table)
+ *
+ * Copyright (c) 2024 Alibaba Group. All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "riscv_smmpt.h"
+#include "pmp.h"
+#include "system/memory.h"
+
+typedef uint64_t load_entry_fn(AddressSpace *, hwaddr,
+ MemTxAttrs, MemTxResult *);
+
+static uint64_t load_entry_32(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, MemTxResult *result)
+{
+ return address_space_ldl(as, addr, attrs, result);
+}
+
+static uint64_t load_entry_64(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, MemTxResult *result)
+{
+ return address_space_ldq(as, addr, attrs, result);
+}
+
+typedef union {
+ uint64_t raw;
+ struct {
+ uint32_t v:1;
+ uint32_t l:1;
+ uint32_t rsv1:5;
+ uint32_t perms:24;
+ uint32_t n:1;
+ } leaf32;
+ struct {
+ uint32_t v:1;
+ uint32_t l:1;
+ uint32_t rsv1:8;
+ uint32_t ppn:22;
+ } nonleaf32;
+ struct {
+ uint64_t v:1;
+ uint64_t l:1;
+ uint64_t rsv1:8;
+ uint64_t perms:48;
+ uint64_t rsv2:5;
+ uint64_t n:1;
+ } leaf64;
+ struct {
+ uint64_t v:1;
+ uint64_t l:1;
+ uint64_t rsv1:8;
+ uint64_t ppn:52;
+ uint64_t rsv2:1;
+ uint64_t n:1;
+ } nonleaf64;
+} mpte_union_t;
+
+static inline bool mpte_is_leaf(uint64_t mpte)
+{
+ return mpte & 0x2;
+}
+
+static inline bool mpte_is_valid(uint64_t mpte)
+{
+ return mpte & 0x1;
+}
+
+static uint64_t mpte_get_rsv(CPURISCVState *env, uint64_t mpte)
+{
+ RISCVMXL mxl = riscv_cpu_mxl(env);
+ bool leaf = mpte_is_leaf(mpte);
+ mpte_union_t *u = (mpte_union_t *)&mpte;
+
+ return (mxl == MXL_RV32)
+ ? (leaf ? u->leaf32.rsv1 : u->nonleaf32.rsv1)
+ : (leaf ? (u->leaf64.rsv1 << 5) | u->leaf64.rsv2
+ : (u->nonleaf64.rsv1 << 1) | u->nonleaf64.rsv2);
+}
I suggest going a little easier on the ternary nesting:
if (mxl == MXL_RV32) {
return leaf ? u->leaf32.rsv1 : u->nonleaf32.rsv1;
}
return leaf ? (u->leaf64.rsv1 << 5) | u->leaf64.rsv2
: (u->nonleaf64.rsv1 << 1) | u->nonleaf64.rsv2);
Everything else LGTM. Thanks,
Daniel
+
+static uint64_t mpte_get_perms(CPURISCVState *env, uint64_t mpte)
+{
+ RISCVMXL mxl = riscv_cpu_mxl(env);
+ mpte_union_t *u = (mpte_union_t *)&mpte;
+
+ return (mxl == MXL_RV32) ? u->leaf32.perms : u->leaf64.perms;
+}
+
+static bool mpte_check_nlnapot(CPURISCVState *env, uint64_t mpte, bool
*nlnapot)
+{
+ RISCVMXL mxl = riscv_cpu_mxl(env);
+ mpte_union_t *u = (mpte_union_t *)&mpte;
+ if (mxl == MXL_RV32) {
+ *nlnapot = false;
+ return true;
+ }
+ *nlnapot = u->nonleaf64.n;
+ return u->nonleaf64.n ? (u->nonleaf64.ppn & 0x1ff) == 0x100 : true;
+}
+
+static uint64_t mpte_get_ppn(CPURISCVState *env, uint64_t mpte, int pn,
+ bool nlnapot)
+{
+ RISCVMXL mxl = riscv_cpu_mxl(env);
+ mpte_union_t *u = (mpte_union_t *)&mpte;
+
+ if (nlnapot) {
+ return deposit64(u->nonleaf64.ppn, 0, 9, pn & 0x1ff);
+ }
+ return (mxl == MXL_RV32) ? u->nonleaf32.ppn : u->nonleaf64.ppn;
+}
+
+/* Caller should assert i before call this interface */
+static int mpt_get_pn(hwaddr addr, int i, mpt_mode_t mode)
+{
+ if (mode == SMMTT34) {
+ return i == 0
+ ? extract64(addr, 15, 10)
+ : extract64(addr, 25, 9);
+ } else {
+ int offset = 16 + i * 9;
+ if ((mode == SMMTT64) && (i == 4)) {
+ return extract64(addr, offset, 12);
+ } else {
+ return extract64(addr, offset, 9);
+ }
+ }
+}
+
+/* Caller should assert i before call this interface */
+static int mpt_get_pi(hwaddr addr, int i, mpt_mode_t mode)
+{
+ if (mode == SMMTT34) {
+ return i == 0
+ ? extract64(addr, 12, 3)
+ : extract64(addr, 22, 3);
+ } else {
+ int offset = 16 + i * 9;
+ return extract64(addr, offset - 4, 4);
+ }
+}
+
+static bool smmpt_lookup(CPURISCVState *env, hwaddr addr, mpt_mode_t mode,
+ mpt_access_t *allowed_access,
+ MMUAccessType access_type)
+{
+ MemTxResult res;
+ MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
+ CPUState *cs = env_cpu(env);
+ hwaddr mpte_addr, base = (hwaddr)env->mptppn << PGSHIFT;
+ load_entry_fn *load_entry;
+ uint32_t mptesize, levels, xwr;
+ int pn, pi, pmp_prot, pmp_ret;
+ uint64_t mpte, perms;
+
+ switch (mode) {
+ case SMMTT34:
+ load_entry = &load_entry_32; levels = 2; mptesize = 4; break;
+ case SMMTT43:
+ load_entry = &load_entry_64; levels = 3; mptesize = 8; break;
+ break;
+ case SMMTT52:
+ load_entry = &load_entry_64; levels = 4; mptesize = 8; break;
+ case SMMTT64:
+ load_entry = &load_entry_64; levels = 5; mptesize = 8; break;
+ case SMMTTBARE:
+ *allowed_access = ACCESS_ALLOW_RWX;
+ return true;
+ default:
+ g_assert_not_reached();
+ break;
+ }
+ for (int i = levels - 1; i >= 0 ; i--) {
+ /* 1. Get pn[i] as the mpt index */
+ pn = mpt_get_pn(addr, i, mode);
+ /* 2. Get mpte address and get mpte */
+ mpte_addr = base + pn * mptesize;
+ pmp_ret = get_physical_address_pmp(env, &pmp_prot, mpte_addr,
+ mptesize, MMU_DATA_LOAD, PRV_M);
+ if (pmp_ret != TRANSLATE_SUCCESS) {
+ return false;
+ }
+ mpte = load_entry(cs->as, mpte_addr, attrs, &res);
+ /* 3. Check valid bit and reserve bits of mpte */
+ if (!mpte_is_valid(mpte) || mpte_get_rsv(env, mpte)) {
+ return false;
+ }
+
+ /* 4. Process non-leaf node */
+ if (!mpte_is_leaf(mpte)) {
+ bool nlnapot = false;
+ if (i == 0) {
+ return false;
+ }
+ if (!mpte_check_nlnapot(env, mpte, &nlnapot)) {
+ return false;
+ }
+ base = mpte_get_ppn(env, mpte, pn, nlnapot) << PGSHIFT;
+ continue;
+ }
+
+ /* 5. Process leaf node */
+ pi = mpt_get_pi(addr, i, mode);
+ perms = mpte_get_perms(env, mpte);
+ xwr = (perms >> (pi * 3)) & 0x7;
+ switch (xwr) {
+ case ACCESS_ALLOW_R:
+ *allowed_access = ACCESS_ALLOW_R;
+ return access_type == MMU_DATA_LOAD;
+ case ACCESS_ALLOW_X:
+ *allowed_access = ACCESS_ALLOW_X;
+ return access_type == MMU_INST_FETCH;
+ case ACCESS_ALLOW_RX:
+ *allowed_access = ACCESS_ALLOW_R;
+ return (access_type == MMU_DATA_LOAD ||
+ access_type == MMU_INST_FETCH);
+ case ACCESS_ALLOW_RW:
+ *allowed_access = ACCESS_ALLOW_RW;
+ return (access_type == MMU_DATA_LOAD ||
+ access_type == MMU_DATA_STORE);
+ case ACCESS_ALLOW_RWX:
+ *allowed_access = ACCESS_ALLOW_RWX;
+ return true;
+ default:
+ return false;
+ }
+ }
+ return false;
+}
+
+bool smmpt_check_access(CPURISCVState *env, hwaddr addr,
+ mpt_access_t *allowed_access, MMUAccessType
access_type)
+{
+ bool mpt_has_access;
+ mpt_mode_t mode = env->mptmode;
+
+ mpt_has_access = smmpt_lookup(env, addr, mode,
+ allowed_access, access_type);
+ return mpt_has_access;
+}
+
+/*
+ * Convert MPT access to TLB page privilege.
+ */
+int smmpt_access_to_page_prot(mpt_access_t mpt_access)
+{
+ int prot;
+ switch (mpt_access) {
+ case ACCESS_ALLOW_R:
+ prot = PAGE_READ;
+ break;
+ case ACCESS_ALLOW_X:
+ prot = PAGE_EXEC;
+ break;
+ case ACCESS_ALLOW_RX:
+ prot = PAGE_READ | PAGE_EXEC;
+ break;
+ case ACCESS_ALLOW_RW:
+ prot = PAGE_READ | PAGE_WRITE;
+ break;
+ case ACCESS_ALLOW_RWX:
+ prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
+ break;
+ default:
+ prot = 0;
+ break;
+ }
+
+ return prot;
+}
diff --git a/target/riscv/riscv_smmpt.h b/target/riscv/riscv_smmpt.h
new file mode 100644
index 0000000000..d5797c6168
--- /dev/null
+++ b/target/riscv/riscv_smmpt.h
@@ -0,0 +1,38 @@
+/*
+ * QEMU RISC-V Smmpt (Memory Protection Table)
+ *
+ * Copyright (c) 2024 Alibaba Group. All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef RISCV_SMPT_H
+#define RISCV_SMPT_H
+
+#include "cpu.h"
+#include "exec/mmu-access-type.h"
+
+typedef enum {
+ SMMTTBARE = 0,
+ SMMTT34 = 1,
+ SMMTT43 = 2,
+ SMMTT52 = 3,
+ SMMTT64 = 4,
+ SMMTTMAX
+} mpt_mode_t;
+
+typedef enum {
+ ACCESS_ALLOW_R = 0b001,
+ ACCESS_ALLOW_X = 0b100,
+ ACCESS_ALLOW_RX = 0b101 ,
+ ACCESS_ALLOW_RW = 0b011,
+ ACCESS_ALLOW_RWX = 0b111,
+} mpt_access_t;
+
+
+int smmpt_access_to_page_prot(mpt_access_t mpt_access);
+bool smmpt_check_access(CPURISCVState *env, hwaddr addr,
+ mpt_access_t *allowed_access,
+ MMUAccessType access_type);
+
+#endif
