[PATCH 0/4] Final (for real this time) patches for arm - pre-PR

[PATCH 0/4] Final (for real this time) patches for arm - pre-PR

[Alex Bennée]

These are all bug fixes for Arm including a recent regression to the
Arm HVF code. Last chance to object as I will roll the PR later today
once Richard is online.

Alex.

Alex Bennée (4):
  Revert "target/arm: Re-use arm_is_psci_call() in HVF"
  target/arm: ensure PSCI register updates are flushed
  target/arm: make HV_EXIT_REASON_CANCELED leave hvf_arch_vcpu_exec
  target/arm: handle unaligned PC during tlb probe

 target/arm/hvf/hvf.c        | 11 ++++++++---
 target/arm/tcg/tlb_helper.c | 21 ++++++++++++++++-----
 2 files changed, 24 insertions(+), 8 deletions(-)

-- 
2.47.3

[PATCH 1/4] Revert "target/arm: Re-use arm_is_psci_call() in HVF"

[Alex Bennée]

This breaks a pure HVF (--disable-tcg) build because the fallback stub
will always report false.

This reverts commit 4695daacc068cd0aa9a91c0063c4f2a9ec9b7ba1.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Christian Stussak <christian.stussak@imaginary.org>
---
 target/arm/hvf/hvf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index de1e8fb8a05..70d34063df8 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -1935,7 +1935,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
         break;
     case EC_AA64_HVC:
         cpu_synchronize_state(cpu);
-        if (arm_is_psci_call(arm_cpu, EXCP_HVC)) {
+        if (arm_cpu->psci_conduit == QEMU_PSCI_CONDUIT_HVC) {
             /* Do NOT advance $pc for HVC */
             if (!hvf_handle_psci_call(cpu)) {
                 trace_hvf_unknown_hvc(env->pc, env->xregs[0]);
@@ -1949,7 +1949,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
         break;
     case EC_AA64_SMC:
         cpu_synchronize_state(cpu);
-        if (arm_is_psci_call(arm_cpu, EXCP_SMC)) {
+        if (arm_cpu->psci_conduit == QEMU_PSCI_CONDUIT_SMC) {
             /* Secure Monitor Call exception, we need to advance $pc */
             advance_pc = true;
 
-- 
2.47.3

[PATCH 2/4] target/arm: ensure PSCI register updates are flushed

[Alex Bennée]

When we handle a host call we report state back to the caller via
registers. Set vcpu_dirty to indicate QEMU is currently the reference
and hoist the flush_cpu_state() and make the call unconditional.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3228
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Christian Stussak <christian.stussak@imaginary.org>

---
v2
  - Fixes->Resolves
---
 target/arm/hvf/hvf.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index 70d34063df8..8e2940217a6 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -1942,6 +1942,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
                 /* SMCCC 1.3 section 5.2 says every unknown SMCCC call returns -1 */
                 env->xregs[0] = -1;
             }
+            cpu->vcpu_dirty = true;
         } else {
             trace_hvf_unknown_hvc(env->pc, env->xregs[0]);
             hvf_raise_exception(cpu, EXCP_UDEF, syn_uncategorized(), 1);
@@ -1958,6 +1959,7 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
                 /* SMCCC 1.3 section 5.2 says every unknown SMCCC call returns -1 */
                 env->xregs[0] = -1;
             }
+            cpu->vcpu_dirty = true;
         } else {
             trace_hvf_unknown_smc(env->xregs[0]);
             hvf_raise_exception(cpu, EXCP_UDEF, syn_uncategorized(), 1);
@@ -1980,10 +1982,12 @@ static int hvf_handle_exception(CPUState *cpu, hv_vcpu_exit_exception_t *excp)
         error_report("0x%llx: unhandled exception ec=0x%x", env->pc, ec);
     }
 
+    /* flush any changed cpu state back to HVF */
+    flush_cpu_state(cpu);
+
     if (advance_pc) {
         uint64_t pc;
 
-        flush_cpu_state(cpu);
 
         r = hv_vcpu_get_reg(cpu->accel->fd, HV_REG_PC, &pc);
         assert_hvf_ok(r);
-- 
2.47.3

[PATCH 3/4] target/arm: make HV_EXIT_REASON_CANCELED leave hvf_arch_vcpu_exec

[Alex Bennée]

Without this we can spin tightly in the main HVF dispatch loop and
never release the lock long enough. As a result the HMP never gets to
run and shutting down the system deadlocks.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3228
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

---
v2
  - expanded commit summary and contents
  - added Resolves link
---
 target/arm/hvf/hvf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index 8e2940217a6..8288b605299 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -2020,6 +2020,7 @@ static int hvf_handle_vmexit(CPUState *cpu, hv_vcpu_exit_t *exit)
         break;
     case HV_EXIT_REASON_CANCELED:
         /* we got kicked, no exit to process */
+        ret = -1;
         break;
     default:
         g_assert_not_reached();
-- 
2.47.3

[PATCH 4/4] target/arm: handle unaligned PC during tlb probe

[Alex Bennée]

PC alignment faults have priority over instruction aborts and we have
code to deal with this in the translation front-ends. However during
tb_lookup we can see a potentially faulting probe which doesn't get a
MemOp set. If the page isn't available this results in
EC_INSNABORT (0x20) instead of EC_PCALIGNMENT (0x22).

As there is no easy way to set the appropriate MemOp in the
instruction fetch probe path lets just detect it in
arm_cpu_tlb_fill_align() ahead of the main alignment check. We also
teach arm_deliver_fault to deliver the right syndrome for
MMU_INST_FETCH alignment issues.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3233
Tested-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20251204203540.1381896-1-alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v2
  - Fixes -> Resolves
---
 target/arm/tcg/tlb_helper.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/target/arm/tcg/tlb_helper.c b/target/arm/tcg/tlb_helper.c
index f1983a5732e..5c689d3b69f 100644
--- a/target/arm/tcg/tlb_helper.c
+++ b/target/arm/tcg/tlb_helper.c
@@ -250,7 +250,11 @@ void arm_deliver_fault(ARMCPU *cpu, vaddr addr,
     fsr = compute_fsr_fsc(env, fi, target_el, mmu_idx, &fsc);
 
     if (access_type == MMU_INST_FETCH) {
-        syn = syn_insn_abort(same_el, fi->ea, fi->s1ptw, fsc);
+        if (fi->type == ARMFault_Alignment) {
+            syn = syn_pcalignment();
+        } else {
+            syn = syn_insn_abort(same_el, fi->ea, fi->s1ptw, fsc);
+        }
         exc = EXCP_PREFETCH_ABORT;
     } else {
         bool gcs = regime_is_gcs(core_to_arm_mmu_idx(env, mmu_idx));
@@ -346,11 +350,18 @@ bool arm_cpu_tlb_fill_align(CPUState *cs, CPUTLBEntryFull *out, vaddr address,
     }
 
     /*
-     * Per R_XCHFJ, alignment fault not due to memory type has
-     * highest precedence.  Otherwise, walk the page table and
-     * and collect the page description.
+     * PC alignment faults should be dealt with at translation time
+     * but we also need to catch them while being probed.
+     *
+     * Then per R_XCHFJ, alignment fault not due to memory type take
+     * precedence. Otherwise, walk the page table and and collect the
+     * page description.
+     *
      */
-    if (address & ((1 << memop_alignment_bits(memop)) - 1)) {
+    if (access_type == MMU_INST_FETCH && !cpu->env.thumb &&
+        (address & 3)) {
+        fi->type = ARMFault_Alignment;
+    } else if (address & ((1 << memop_alignment_bits(memop)) - 1)) {
         fi->type = ARMFault_Alignment;
     } else if (!get_phys_addr(&cpu->env, address, access_type, memop,
                               core_to_arm_mmu_idx(&cpu->env, mmu_idx),
-- 
2.47.3

Re: [PATCH 2/4] target/arm: ensure PSCI register updates are flushed

[Philippe Mathieu-Daudé]

On 9/12/25 10:24, Alex Bennée wrote:
> When we handle a host call we report state back to the caller via
> registers. Set vcpu_dirty to indicate QEMU is currently the reference
> and hoist the flush_cpu_state() and make the call unconditional.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3228
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Tested-by: Christian Stussak <christian.stussak@imaginary.org>
> 
> ---
> v2
>    - Fixes->Resolves
> ---
>   target/arm/hvf/hvf.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)

Again:
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>