[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] target/riscv: Fix PMP propagation for tlb
|
From: |
Alistair Francis |
|
Subject: |
Re: [PATCH] target/riscv: Fix PMP propagation for tlb |
|
Date: |
Mon, 24 Oct 2022 12:32:07 +1000 |
On Wed, Oct 12, 2022 at 4:01 PM LIU Zhiwei <zhiwei_liu@linux.alibaba.com> wrote:
>
> Only the pmp index that be checked by pmp_hart_has_privs can be used
> by pmp_get_tlb_size to avoid an error pmp index.
>
> Before modification, we may use an error pmp index. For example,
> we check address 0x4fc, and the size 0x4 in pmp_hart_has_privs. If there
> is an pmp rule, valid range is [0x4fc, 0x500), then pmp_hart_has_privs
> will return true;
>
> However, this checked pmp index is discarded as pmp_hart_has_privs
> return bool value. In pmp_is_range_in_tlb, it will traverse all pmp
> rules. The tlb_sa will be 0x0, and tlb_ea will be 0xfff. If there is
> a pmp rule [0x10, 0x14), it will be misused as it is legal in
> pmp_get_tlb_size.
>
> As we have already known the correct pmp index, just remove the
> remove the pmp_is_range_in_tlb and get tlb size directly from
> pmp_get_tlb_size.
>
> Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Alistair
> ---
> target/riscv/cpu_helper.c | 16 ++++---
> target/riscv/pmp.c | 90 +++++++++++++--------------------------
> target/riscv/pmp.h | 6 +--
> 3 files changed, 42 insertions(+), 70 deletions(-)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 278d163803..5d66246c2c 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -706,24 +706,26 @@ static int get_physical_address_pmp(CPURISCVState *env,
> int *prot,
> int mode)
> {
> pmp_priv_t pmp_priv;
> - target_ulong tlb_size_pmp = 0;
> + int pmp_index = -1;
>
> if (!riscv_feature(env, RISCV_FEATURE_PMP)) {
> *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
> return TRANSLATE_SUCCESS;
> }
>
> - if (!pmp_hart_has_privs(env, addr, size, 1 << access_type, &pmp_priv,
> - mode)) {
> + pmp_index = pmp_hart_has_privs(env, addr, size, 1 << access_type,
> + &pmp_priv, mode);
> + if (pmp_index < 0) {
> *prot = 0;
> return TRANSLATE_PMP_FAIL;
> }
>
> *prot = pmp_priv_to_page_prot(pmp_priv);
> - if (tlb_size != NULL) {
> - if (pmp_is_range_in_tlb(env, addr & ~(*tlb_size - 1),
> &tlb_size_pmp)) {
> - *tlb_size = tlb_size_pmp;
> - }
> + if ((tlb_size != NULL) && pmp_index != MAX_RISCV_PMPS) {
> + target_ulong tlb_sa = addr & ~(TARGET_PAGE_SIZE - 1);
> + target_ulong tlb_ea = tlb_sa + TARGET_PAGE_SIZE - 1;
> +
> + *tlb_size = pmp_get_tlb_size(env, pmp_index, tlb_sa, tlb_ea);
> }
>
> return TRANSLATE_SUCCESS;
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index 2b43e399b8..d1126a6066 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -292,8 +292,11 @@ static bool pmp_hart_has_privs_default(CPURISCVState
> *env, target_ulong addr,
>
> /*
> * 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
> */
> -bool pmp_hart_has_privs(CPURISCVState *env, target_ulong addr,
> +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)
> {
> @@ -305,8 +308,10 @@ bool pmp_hart_has_privs(CPURISCVState *env, target_ulong
> addr,
>
> /* Short cut if no rules */
> if (0 == pmp_get_num_rules(env)) {
> - return pmp_hart_has_privs_default(env, addr, size, privs,
> - allowed_privs, mode);
> + if (pmp_hart_has_privs_default(env, addr, size, privs,
> + allowed_privs, mode)) {
> + ret = MAX_RISCV_PMPS;
> + }
> }
>
> if (size == 0) {
> @@ -333,7 +338,7 @@ bool pmp_hart_has_privs(CPURISCVState *env, target_ulong
> addr,
> if ((s + e) == 1) {
> qemu_log_mask(LOG_GUEST_ERROR,
> "pmp violation - access is partially inside\n");
> - ret = 0;
> + ret = -1;
> break;
> }
>
> @@ -436,18 +441,22 @@ bool pmp_hart_has_privs(CPURISCVState *env,
> target_ulong addr,
> }
> }
>
> - ret = ((privs & *allowed_privs) == privs);
> + if ((privs & *allowed_privs) == privs) {
> + ret = i;
> + }
> break;
> }
> }
>
> /* No rule matched */
> if (ret == -1) {
> - return pmp_hart_has_privs_default(env, addr, size, privs,
> - allowed_privs, mode);
> + if (pmp_hart_has_privs_default(env, addr, size, privs,
> + allowed_privs, mode)) {
> + ret = MAX_RISCV_PMPS;
> + }
> }
>
> - return ret == 1 ? true : false;
> + return ret;
> }
>
> /*
> @@ -586,64 +595,25 @@ target_ulong mseccfg_csr_read(CPURISCVState *env)
> * Calculate the TLB size if the start address or the end address of
> * PMP entry is presented in the TLB page.
> */
> -static target_ulong pmp_get_tlb_size(CPURISCVState *env, int pmp_index,
> - target_ulong tlb_sa, target_ulong
> tlb_ea)
> +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 pmp_ea - pmp_sa + 1;
> - }
> -
> - if (pmp_sa >= tlb_sa && pmp_sa <= tlb_ea && pmp_ea >= tlb_ea) {
> - return tlb_ea - pmp_sa + 1;
> - }
> -
> - if (pmp_ea <= tlb_ea && pmp_ea >= tlb_sa && pmp_sa <= tlb_sa) {
> - return pmp_ea - tlb_sa + 1;
> - }
> -
> - return 0;
> -}
> -
> -/*
> - * Check is there a PMP entry which range covers this page. If so,
> - * try to find the minimum granularity for the TLB size.
> - */
> -bool pmp_is_range_in_tlb(CPURISCVState *env, hwaddr tlb_sa,
> - target_ulong *tlb_size)
> -{
> - int i;
> - target_ulong val;
> - target_ulong tlb_ea = (tlb_sa + TARGET_PAGE_SIZE - 1);
> -
> - for (i = 0; i < MAX_RISCV_PMPS; i++) {
> - val = pmp_get_tlb_size(env, i, tlb_sa, tlb_ea);
> - if (val) {
> - if (*tlb_size == 0 || *tlb_size > val) {
> - *tlb_size = val;
> - }
> - }
> - }
> -
> - if (*tlb_size != 0) {
> + 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.
> - */
> - if (*tlb_size < TARGET_PAGE_SIZE) {
> - *tlb_size = 1;
> - }
> -
> - return true;
> + * 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;
> }
> -
> - return false;
> }
>
> /*
> diff --git a/target/riscv/pmp.h b/target/riscv/pmp.h
> index a8dd797476..da32c61c85 100644
> --- a/target/riscv/pmp.h
> +++ b/target/riscv/pmp.h
> @@ -72,11 +72,11 @@ target_ulong mseccfg_csr_read(CPURISCVState *env);
> void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
> target_ulong val);
> target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index);
> -bool pmp_hart_has_privs(CPURISCVState *env, target_ulong addr,
> +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);
> -bool pmp_is_range_in_tlb(CPURISCVState *env, hwaddr tlb_sa,
> - target_ulong *tlb_size);
> +target_ulong pmp_get_tlb_size(CPURISCVState *env, int pmp_index,
> + target_ulong tlb_sa, target_ulong tlb_ea);
> void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index);
> void pmp_update_rule_nums(CPURISCVState *env);
> uint32_t pmp_get_num_rules(CPURISCVState *env);
> --
> 2.25.1
>
>