In aarch64_sve_narrow_vq() we assert that the new VQ is within
the maximum supported range for the CPU. We forgot to update
this to account for SME, which might have a different maximum.

Update the assert to permit any VQ which is valid for either
SVE or SME.

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
CC stable on this one, because it might also be a problem for
a CPU with both SME and SVE but where the SVE max VL is less
than the SME max VL.
---
 target/arm/helper.c    | 2 +-
 target/arm/internals.h | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index dce648b482..7ceab0b503 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10076,7 +10076,7 @@ void aarch64_sve_narrow_vq(CPUARMState *env, unsigned vq)
     uint64_t pmask;
 
     assert(vq >= 1 && vq <= ARM_MAX_VQ);
-    assert(vq <= env_archcpu(env)->sve_max_vq);
+    assert(vq <= arm_max_vq(env_archcpu(env)));
 
     /* Zap the high bits of the zregs.  */
     for (i = 0; i < 32; i++) {
diff --git a/target/arm/internals.h b/target/arm/internals.h
index f7b641342a..8ec2750847 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1808,6 +1808,15 @@ static inline uint64_t arm_mdcr_el2_eff(CPUARMState *env)
     ((1 << (1 - 1)) | (1 << (2 - 1)) |                  \
      (1 << (4 - 1)) | (1 << (8 - 1)) | (1 << (16 - 1)))
 
+/*
+ * Return the maximum SVE/SME VQ for this CPU. This defines
+ * the maximum possible size of the Zn vector registers.
+ */
+static inline int arm_max_vq(ARMCPU *cpu)
+{
+    return MAX(cpu->sve_max_vq, cpu->sme_max_vq);
+}
+
 /*
  * Return true if it is possible to take a fine-grained-trap to EL2.
  */
-- 
2.43.0

On 1/29/26 21:34, Peter Maydell wrote:
> In aarch64_sve_narrow_vq() we assert that the new VQ is within
> the maximum supported range for the CPU. We forgot to update
> this to account for SME, which might have a different maximum.
> 
> Update the assert to permit any VQ which is valid for either
> SVE or SME.
> 
> Cc:qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
> CC stable on this one, because it might also be a problem for
> a CPU with both SME and SVE but where the SVE max VL is less
> than the SME max VL.
> ---
>   target/arm/helper.c    | 2 +-
>   target/arm/internals.h | 9 +++++++++
>   2 files changed, 10 insertions(+), 1 deletion(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

Peter Maydell <peter.maydell@linaro.org> writes:

> In aarch64_sve_narrow_vq() we assert that the new VQ is within
> the maximum supported range for the CPU. We forgot to update
> this to account for SME, which might have a different maximum.
>
> Update the assert to permit any VQ which is valid for either
> SVE or SME.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro

On 29/1/26 12:34, Peter Maydell wrote:
> In aarch64_sve_narrow_vq() we assert that the new VQ is within
> the maximum supported range for the CPU. We forgot to update
> this to account for SME, which might have a different maximum.
> 
> Update the assert to permit any VQ which is valid for either
> SVE or SME.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> CC stable on this one, because it might also be a problem for
> a CPU with both SME and SVE but where the SVE max VL is less
> than the SME max VL.
> ---
>   target/arm/helper.c    | 2 +-
>   target/arm/internals.h | 9 +++++++++
>   2 files changed, 10 insertions(+), 1 deletion(-)

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