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c1027460dc
qemu/target/riscv/pmp.c
Himanshu Chauhan 90b1fafce0
target/riscv: Smepmp: Skip applying default rules when address matches 
When MSECCFG.MML is set, after checking the address range in PMP if the
asked permissions are not same as programmed in PMP, the default
permissions are applied. This should only be the case when there
is no matching address is found.

This patch skips applying default rules when matching address range
is found. It returns the index of the match PMP entry.

Fixes: 824cac681c (target/riscv: Fix PMP propagation for tlb)
Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230209055206.229392-1-hchauhan@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-02-23 14:21:32 -08:00

641 lines
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/*
* QEMU RISC-V PMP (Physical Memory Protection)
*
* Author: Daire McNamara, daire.mcnamara@emdalo.com
* Ivan Griffin, ivan.griffin@emdalo.com
*
* This provides a RISC-V Physical Memory Protection implementation
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2 or later, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qapi/error.h"
#include "cpu.h"
#include "trace.h"
#include "exec/exec-all.h"
static void pmp_write_cfg(CPURISCVState *env, uint32_t addr_index,
uint8_t val);
static uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t addr_index);
static void pmp_update_rule(CPURISCVState *env, uint32_t pmp_index);
/*
* Accessor method to extract address matching type 'a field' from cfg reg
*/
static inline uint8_t pmp_get_a_field(uint8_t cfg)
{
uint8_t a = cfg >> 3;
return a & 0x3;
}
/*
* Check whether a PMP is locked or not.
*/
static inline int pmp_is_locked(CPURISCVState *env, uint32_t pmp_index)
{
if (env->pmp_state.pmp[pmp_index].cfg_reg & PMP_LOCK) {
return 1;
}
/* Top PMP has no 'next' to check */
if ((pmp_index + 1u) >= MAX_RISCV_PMPS) {
return 0;
}
return 0;
}
/*
* Count the number of active rules.
*/
uint32_t pmp_get_num_rules(CPURISCVState *env)
{
return env->pmp_state.num_rules;
}
/*
* Accessor to get the cfg reg for a specific PMP/HART
*/
static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
{
if (pmp_index < MAX_RISCV_PMPS) {
return env->pmp_state.pmp[pmp_index].cfg_reg;
}
return 0;
}
/*
* Accessor to set the cfg reg for a specific PMP/HART
* Bounds checks and relevant lock bit.
*/
static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
{
if (pmp_index < MAX_RISCV_PMPS) {
bool locked = true;
if (riscv_feature(env, RISCV_FEATURE_EPMP)) {
/* mseccfg.RLB is set */
if (MSECCFG_RLB_ISSET(env)) {
locked = false;
}
/* mseccfg.MML is not set */
if (!MSECCFG_MML_ISSET(env) && !pmp_is_locked(env, pmp_index)) {
locked = false;
}
/* mseccfg.MML is set */
if (MSECCFG_MML_ISSET(env)) {
/* not adding execute bit */
if ((val & PMP_LOCK) != 0 && (val & PMP_EXEC) != PMP_EXEC) {
locked = false;
}
/* shared region and not adding X bit */
if ((val & PMP_LOCK) != PMP_LOCK &&
(val & 0x7) != (PMP_WRITE | PMP_EXEC)) {
locked = false;
}
}
} else {
if (!pmp_is_locked(env, pmp_index)) {
locked = false;
}
}
if (locked) {
qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
} else {
env->pmp_state.pmp[pmp_index].cfg_reg = val;
pmp_update_rule(env, pmp_index);
}
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"ignoring pmpcfg write - out of bounds\n");
}
}
static void pmp_decode_napot(target_ulong a, target_ulong *sa, target_ulong *ea)
{
/*
aaaa...aaa0 8-byte NAPOT range
aaaa...aa01 16-byte NAPOT range
aaaa...a011 32-byte NAPOT range
...
aa01...1111 2^XLEN-byte NAPOT range
a011...1111 2^(XLEN+1)-byte NAPOT range
0111...1111 2^(XLEN+2)-byte NAPOT range
1111...1111 Reserved
*/
a = (a << 2) | 0x3;
*sa = a & (a + 1);
*ea = a | (a + 1);
}
void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
{
uint8_t this_cfg = env->pmp_state.pmp[pmp_index].cfg_reg;
target_ulong this_addr = env->pmp_state.pmp[pmp_index].addr_reg;
target_ulong prev_addr = 0u;
target_ulong sa = 0u;
target_ulong ea = 0u;
if (pmp_index >= 1u) {
prev_addr = env->pmp_state.pmp[pmp_index - 1].addr_reg;
}
switch (pmp_get_a_field(this_cfg)) {
case PMP_AMATCH_OFF:
sa = 0u;
ea = -1;
break;
case PMP_AMATCH_TOR:
sa = prev_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
ea = (this_addr << 2) - 1u;
if (sa > ea) {
sa = ea = 0u;
}
break;
case PMP_AMATCH_NA4:
sa = this_addr << 2; /* shift up from [xx:0] to [xx+2:2] */
ea = (sa + 4u) - 1u;
break;
case PMP_AMATCH_NAPOT:
pmp_decode_napot(this_addr, &sa, &ea);
break;
default:
sa = 0u;
ea = 0u;
break;
}
env->pmp_state.addr[pmp_index].sa = sa;
env->pmp_state.addr[pmp_index].ea = ea;
}
void pmp_update_rule_nums(CPURISCVState *env)
{
int i;
env->pmp_state.num_rules = 0;
for (i = 0; i < MAX_RISCV_PMPS; i++) {
const uint8_t a_field =
pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
if (PMP_AMATCH_OFF != a_field) {
env->pmp_state.num_rules++;
}
}
}
/* Convert cfg/addr reg values here into simple 'sa' --> start address and 'ea'
* end address values.
* This function is called relatively infrequently whereas the check that
* an address is within a pmp rule is called often, so optimise that one
*/
static void pmp_update_rule(CPURISCVState *env, uint32_t pmp_index)
{
pmp_update_rule_addr(env, pmp_index);
pmp_update_rule_nums(env);
}
static int pmp_is_in_range(CPURISCVState *env, int pmp_index, target_ulong addr)
{
int result = 0;
if ((addr >= env->pmp_state.addr[pmp_index].sa)
&& (addr <= env->pmp_state.addr[pmp_index].ea)) {
result = 1;
} else {
result = 0;
}
return result;
}
/*
* Check if the address has required RWX privs when no PMP entry is matched.
*/
static bool pmp_hart_has_privs_default(CPURISCVState *env, target_ulong addr,
target_ulong size, pmp_priv_t privs, pmp_priv_t *allowed_privs,
target_ulong mode)
{
bool ret;
if (riscv_feature(env, RISCV_FEATURE_EPMP)) {
if (MSECCFG_MMWP_ISSET(env)) {
/*
* The Machine Mode Whitelist Policy (mseccfg.MMWP) is set
* so we default to deny all, even for M-mode.
*/
*allowed_privs = 0;
return false;
} else if (MSECCFG_MML_ISSET(env)) {
/*
* The Machine Mode Lockdown (mseccfg.MML) bit is set
* so we can only execute code in M-mode with an applicable
* rule. Other modes are disabled.
*/
if (mode == PRV_M && !(privs & PMP_EXEC)) {
ret = true;
*allowed_privs = PMP_READ | PMP_WRITE;
} else {
ret = false;
*allowed_privs = 0;
}
return ret;
}
}
if ((!riscv_feature(env, RISCV_FEATURE_PMP)) || (mode == PRV_M)) {
/*
* Privileged spec v1.10 states if HW doesn't implement any PMP entry
* or no PMP entry matches an M-Mode access, the access succeeds.
*/
ret = true;
*allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
} else {
/*
* Other modes are not allowed to succeed if they don't * match a rule,
* but there are rules. We've checked for no rule earlier in this
* function.
*/
ret = false;
*allowed_privs = 0;
}
return ret;
}
/*
* Public Interface
*/
/*
* Check if the address has required RWX privs to complete desired operation
* Return PMP rule index if a pmp rule match
* Return MAX_RISCV_PMPS if default match
* Return negtive value if no match
*/
int pmp_hart_has_privs(CPURISCVState *env, target_ulong addr,
target_ulong size, pmp_priv_t privs, pmp_priv_t *allowed_privs,
target_ulong mode)
{
int i = 0;
int ret = -1;
int pmp_size = 0;
target_ulong s = 0;
target_ulong e = 0;
/* Short cut if no rules */
if (0 == pmp_get_num_rules(env)) {
if (pmp_hart_has_privs_default(env, addr, size, privs,
allowed_privs, mode)) {
ret = MAX_RISCV_PMPS;
}
}
if (size == 0) {
if (riscv_feature(env, RISCV_FEATURE_MMU)) {
/*
* If size is unknown (0), assume that all bytes
* from addr to the end of the page will be accessed.
*/
pmp_size = -(addr | TARGET_PAGE_MASK);
} else {
pmp_size = sizeof(target_ulong);
}
} else {
pmp_size = size;
}
/* 1.10 draft priv spec states there is an implicit order
from low to high */
for (i = 0; i < MAX_RISCV_PMPS; i++) {
s = pmp_is_in_range(env, i, addr);
e = pmp_is_in_range(env, i, addr + pmp_size - 1);
/* partially inside */
if ((s + e) == 1) {
qemu_log_mask(LOG_GUEST_ERROR,
"pmp violation - access is partially inside\n");
ret = -1;
break;
}
/* fully inside */
const uint8_t a_field =
pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
/*
* Convert the PMP permissions to match the truth table in the
* ePMP spec.
*/
const uint8_t epmp_operation =
((env->pmp_state.pmp[i].cfg_reg & PMP_LOCK) >> 4) |
((env->pmp_state.pmp[i].cfg_reg & PMP_READ) << 2) |
(env->pmp_state.pmp[i].cfg_reg & PMP_WRITE) |
((env->pmp_state.pmp[i].cfg_reg & PMP_EXEC) >> 2);
if (((s + e) == 2) && (PMP_AMATCH_OFF != a_field)) {
/*
* If the PMP entry is not off and the address is in range,
* do the priv check
*/
if (!MSECCFG_MML_ISSET(env)) {
/*
* If mseccfg.MML Bit is not set, do pmp priv check
* This will always apply to regular PMP.
*/
*allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
if ((mode != PRV_M) || pmp_is_locked(env, i)) {
*allowed_privs &= env->pmp_state.pmp[i].cfg_reg;
}
} else {
/*
* If mseccfg.MML Bit set, do the enhanced pmp priv check
*/
if (mode == PRV_M) {
switch (epmp_operation) {
case 0:
case 1:
case 4:
case 5:
case 6:
case 7:
case 8:
*allowed_privs = 0;
break;
case 2:
case 3:
case 14:
*allowed_privs = PMP_READ | PMP_WRITE;
break;
case 9:
case 10:
*allowed_privs = PMP_EXEC;
break;
case 11:
case 13:
*allowed_privs = PMP_READ | PMP_EXEC;
break;
case 12:
case 15:
*allowed_privs = PMP_READ;
break;
default:
g_assert_not_reached();
}
} else {
switch (epmp_operation) {
case 0:
case 8:
case 9:
case 12:
case 13:
case 14:
*allowed_privs = 0;
break;
case 1:
case 10:
case 11:
*allowed_privs = PMP_EXEC;
break;
case 2:
case 4:
case 15:
*allowed_privs = PMP_READ;
break;
case 3:
case 6:
*allowed_privs = PMP_READ | PMP_WRITE;
break;
case 5:
*allowed_privs = PMP_READ | PMP_EXEC;
break;
case 7:
*allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC;
break;
default:
g_assert_not_reached();
}
}
}
/*
* If matching address range was found, the protection bits
* defined with PMP must be used. We shouldn't fallback on
* finding default privileges.
*/
ret = i;
break;
}
}
/* No rule matched */
if (ret == -1) {
if (pmp_hart_has_privs_default(env, addr, size, privs,
allowed_privs, mode)) {
ret = MAX_RISCV_PMPS;
}
}
return ret;
}
/*
* Handle a write to a pmpcfg CSR
*/
void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index,
target_ulong val)
{
int i;
uint8_t cfg_val;
int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
trace_pmpcfg_csr_write(env->mhartid, reg_index, val);
for (i = 0; i < pmpcfg_nums; i++) {
cfg_val = (val >> 8 * i) & 0xff;
pmp_write_cfg(env, (reg_index * 4) + i, cfg_val);
}
/* If PMP permission of any addr has been changed, flush TLB pages. */
tlb_flush(env_cpu(env));
}
/*
* Handle a read from a pmpcfg CSR
*/
target_ulong pmpcfg_csr_read(CPURISCVState *env, uint32_t reg_index)
{
int i;
target_ulong cfg_val = 0;
target_ulong val = 0;
int pmpcfg_nums = 2 << riscv_cpu_mxl(env);
for (i = 0; i < pmpcfg_nums; i++) {
val = pmp_read_cfg(env, (reg_index * 4) + i);
cfg_val |= (val << (i * 8));
}
trace_pmpcfg_csr_read(env->mhartid, reg_index, cfg_val);
return cfg_val;
}
/*
* Handle a write to a pmpaddr CSR
*/
void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
target_ulong val)
{
trace_pmpaddr_csr_write(env->mhartid, addr_index, val);
if (addr_index < MAX_RISCV_PMPS) {
/*
* In TOR mode, need to check the lock bit of the next pmp
* (if there is a next).
*/
if (addr_index + 1 < MAX_RISCV_PMPS) {
uint8_t pmp_cfg = env->pmp_state.pmp[addr_index + 1].cfg_reg;
if (pmp_cfg & PMP_LOCK &&
PMP_AMATCH_TOR == pmp_get_a_field(pmp_cfg)) {
qemu_log_mask(LOG_GUEST_ERROR,
"ignoring pmpaddr write - pmpcfg + 1 locked\n");
return;
}
}
if (!pmp_is_locked(env, addr_index)) {
env->pmp_state.pmp[addr_index].addr_reg = val;
pmp_update_rule(env, addr_index);
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"ignoring pmpaddr write - locked\n");
}
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"ignoring pmpaddr write - out of bounds\n");
}
}
/*
* Handle a read from a pmpaddr CSR
*/
target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
{
target_ulong val = 0;
if (addr_index < MAX_RISCV_PMPS) {
val = env->pmp_state.pmp[addr_index].addr_reg;
trace_pmpaddr_csr_read(env->mhartid, addr_index, val);
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"ignoring pmpaddr read - out of bounds\n");
}
return val;
}
/*
* Handle a write to a mseccfg CSR
*/
void mseccfg_csr_write(CPURISCVState *env, target_ulong val)
{
int i;
trace_mseccfg_csr_write(env->mhartid, val);
/* RLB cannot be enabled if it's already 0 and if any regions are locked */
if (!MSECCFG_RLB_ISSET(env)) {
for (i = 0; i < MAX_RISCV_PMPS; i++) {
if (pmp_is_locked(env, i)) {
val &= ~MSECCFG_RLB;
break;
}
}
}
/* Sticky bits */
val |= (env->mseccfg & (MSECCFG_MMWP | MSECCFG_MML));
env->mseccfg = val;
}
/*
* Handle a read from a mseccfg CSR
*/
target_ulong mseccfg_csr_read(CPURISCVState *env)
{
trace_mseccfg_csr_read(env->mhartid, env->mseccfg);
return env->mseccfg;
}
/*
* Calculate the TLB size if the start address or the end address of
* PMP entry is presented in the TLB page.
*/
target_ulong pmp_get_tlb_size(CPURISCVState *env, int pmp_index,
target_ulong tlb_sa, target_ulong tlb_ea)
{
target_ulong pmp_sa = env->pmp_state.addr[pmp_index].sa;
target_ulong pmp_ea = env->pmp_state.addr[pmp_index].ea;
if (pmp_sa <= tlb_sa && pmp_ea >= tlb_ea) {
return TARGET_PAGE_SIZE;
} else {
/*
* At this point we have a tlb_size that is the smallest possible size
* That fits within a TARGET_PAGE_SIZE and the PMP region.
*
* If the size is less then TARGET_PAGE_SIZE we drop the size to 1.
* This means the result isn't cached in the TLB and is only used for
* a single translation.
*/
return 1;
}
}
/*
* Convert PMP privilege to TLB page privilege.
*/
int pmp_priv_to_page_prot(pmp_priv_t pmp_priv)
{
int prot = 0;
if (pmp_priv & PMP_READ) {
prot |= PAGE_READ;
}
if (pmp_priv & PMP_WRITE) {
prot |= PAGE_WRITE;
}
if (pmp_priv & PMP_EXEC) {
prot |= PAGE_EXEC;
}
return prot;
}
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