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target/riscv: expose *envcfg csr and priv to qemu-user as well

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Execution environment config CSR controlling user env and current
privilege state shouldn't be limited to qemu-system only. *envcfg
CSRs control enabling of features in next lesser mode. In some cases
bits *envcfg CSR can be lit up by kernel as part of kernel policy or
software (user app) can choose to opt-in by issuing a system call
(e.g. prctl). In case of qemu-user, it should be no different because
qemu is providing underlying execution environment facility and thus
either should provide some default value in *envcfg CSRs or react to
system calls (prctls) initiated from application. priv is set to PRV_U
and menvcfg/senvcfg set to 0 for qemu-user on reest.

`henvcfg` has been left for qemu-system only because it is not expected
that someone will use qemu-user where application is expected to have
hypervisor underneath which is controlling its execution environment. If
such a need arises then `henvcfg` could be exposed as well.

Relevant discussion:
https://lore.kernel.org/all/CAKmqyKOTVWPFep2msTQVdUmJErkH+bqCcKEQ4hAnyDFPdWKe0Q@mail.gmail.com/

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241008225010.1861630-2-debug@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Deepak Gupta 2024-10-08 15:49:51 -07:00 committed by Alistair Francis
parent 53c1557b23
commit f9158a9240
2 changed files with 10 additions and 4 deletions
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5
target/riscv/cpu.c
View File

@ -1004,7 +1004,12 @@ static void riscv_cpu_reset_hold(Object *obj, ResetType type)
}
pmp_unlock_entries(env);
#else
env->priv = PRV_U;
env->senvcfg = 0;
env->menvcfg = 0;
#endif
env->xl = riscv_cpu_mxl(env);
riscv_cpu_update_mask(env);
cs->exception_index = RISCV_EXCP_NONE;

9
target/riscv/cpu.h
View File

@ -234,8 +234,12 @@ struct CPUArchState {
uint32_t elf_flags;
#endif
#ifndef CONFIG_USER_ONLY
target_ulong priv;
/* CSRs for execution environment configuration */
uint64_t menvcfg;
target_ulong senvcfg;
#ifndef CONFIG_USER_ONLY
/* This contains QEMU specific information about the virt state. */
bool virt_enabled;
target_ulong geilen;
@ -445,12 +449,9 @@ struct CPUArchState {
target_ulong upmmask;
target_ulong upmbase;
/* CSRs for execution environment configuration */
uint64_t menvcfg;
uint64_t mstateen[SMSTATEEN_MAX_COUNT];
uint64_t hstateen[SMSTATEEN_MAX_COUNT];
uint64_t sstateen[SMSTATEEN_MAX_COUNT];
target_ulong senvcfg;
uint64_t henvcfg;
#endif
target_ulong cur_pmmask;