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target/riscv: Add proper two-stage lookup exception detection

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The current two-stage lookup detection in riscv_cpu_do_interrupt falls
short of its purpose, as all it checks is whether two-stage address
translation either via the hypervisor-load store instructions or the
MPRV feature would be allowed.

What we really need instead is whether two-stage address translation was
active when the exception was raised. However, in riscv_cpu_do_interrupt
we do not have the information to reliably detect this. Therefore, when
we raise a memory fault exception we have to record whether two-stage
address translation is active.

Backports ec352d0cab58a7bf66019057d0dfcffd9e7785a8
This commit is contained in:
Georg Kotheimer 2021-03-30 15:19:22 -04:00 committed by Lioncash
parent d18b402732
commit a1edab5abf
3 changed files with 11 additions and 13 deletions
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1
qemu/target/riscv/cpu.c
View file

@ -313,6 +313,7 @@ static void riscv_cpu_reset(CPUState *cs)
env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
env->mcause = 0;
env->pc = env->resetvec;
env->two_stage_lookup = false;
#endif
cs->exception_index = EXCP_NONE;
env->load_res = -1;

4
qemu/target/riscv/cpu.h
View file

@ -226,6 +226,10 @@ struct CPURISCVState {
target_ulong satp_hs;
uint64_t mstatus_hs;
/* Signals whether the current exception occurred with two-stage address
translation active. */
bool two_stage_lookup;
target_ulong scounteren;
target_ulong mcounteren;

19
qemu/target/riscv/cpu_helper.c
View file

@ -647,6 +647,7 @@ static void raise_mmu_exception(CPURISCVState *env, target_ulong address,
g_assert_not_reached();
}
env->badaddr = address;
env->two_stage_lookup = two_stage;
}
hwaddr riscv_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
@ -708,6 +709,8 @@ void riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
g_assert_not_reached();
}
env->badaddr = addr;
env->two_stage_lookup = riscv_cpu_virt_enabled(env) ||
riscv_cpu_two_stage_lookup(mmu_idx);
riscv_raise_exception(env, cs->exception_index, retaddr);
}
#endif
@ -944,16 +947,8 @@ void riscv_cpu_do_interrupt(CPUState *cs)
/* handle the trap in S-mode */
if (riscv_has_ext(env, RVH)) {
target_ulong hdeleg = async ? env->hideleg : env->hedeleg;
bool two_stage_lookup = false;
if (env->priv == PRV_M ||
(env->priv == PRV_S && !riscv_cpu_virt_enabled(env)) ||
(env->priv == PRV_U && !riscv_cpu_virt_enabled(env) &&
get_field(env->hstatus, HSTATUS_HU))) {
two_stage_lookup = true;
}
if ((riscv_cpu_virt_enabled(env) || two_stage_lookup) && write_tval) {
if (env->two_stage_lookup && write_tval) {
/*
* If we are writing a guest virtual address to stval, set
* this to 1. If we are trapping to VS we will set this to 0
@ -991,10 +986,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
riscv_cpu_set_force_hs_excep(env, 0);
} else {
/* Trap into HS mode */
if (!two_stage_lookup) {
env->hstatus = set_field(env->hstatus, HSTATUS_SPV,
riscv_cpu_virt_enabled(env));
}
env->hstatus = set_field(env->hstatus, HSTATUS_SPV, false);
htval = env->guest_phys_fault_addr;
}
}
@ -1051,6 +1043,7 @@ void riscv_cpu_do_interrupt(CPUState *cs)
* RISC-V ISA Specification.
*/
env->two_stage_lookup = false;
#endif
cs->exception_index = EXCP_NONE; /* mark handled to qemu */
}