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[PATCH v2] target/riscv: Add proper two-stage lookup exception detection
From: |
Georg Kotheimer |
Subject: |
[PATCH v2] target/riscv: Add proper two-stage lookup exception detection |
Date: |
Fri, 19 Mar 2021 15:14:59 +0100 |
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.
Signed-off-by: Georg Kotheimer <georg.kotheimer@kernkonzept.com>
---
Unfortunately, I tested the previous version of the patch only against
the RISC-V softmmu target, not against the linux-user target.
I modified the patch, so that the two_stage_lookup is neither present
nor updated for the linux-user target.
target/riscv/cpu.c | 1 +
target/riscv/cpu.h | 4 ++++
target/riscv/cpu_helper.c | 21 ++++++++-------------
3 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index ddea8fbeeb..e8c4455525 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -356,6 +356,7 @@ static void riscv_cpu_reset(DeviceState *dev)
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;
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 0edb2826a2..0a33d387ba 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -213,6 +213,10 @@ 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;
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 2f43939fb6..af00728829 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -605,6 +605,7 @@ 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)
@@ -646,6 +647,8 @@ void riscv_cpu_do_transaction_failed(CPUState *cs, hwaddr
physaddr,
}
env->badaddr = addr;
+ env->two_stage_lookup = riscv_cpu_virt_enabled(env) ||
+ riscv_cpu_two_stage_lookup(mmu_idx);
riscv_raise_exception(&cpu->env, cs->exception_index, retaddr);
}
@@ -669,6 +672,8 @@ 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 /* !CONFIG_USER_ONLY */
@@ -910,16 +915,8 @@ 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
@@ -957,10 +954,7 @@ 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;
}
}
@@ -1016,6 +1010,7 @@ 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 */
}
--
2.31.0
- [PATCH v2] target/riscv: Add proper two-stage lookup exception detection,
Georg Kotheimer <=