[v2,1/4] target/arm/cpu: Introduce sve_vq_supported bitmap

Commit Message

Andrew Jones Aug. 23, 2021, 4:06 p.m. UTC

Allow CPUs that support SVE to specify which SVE vector lengths they
support by setting them in this bitmap. Currently only the 'max' and
'host' CPU types supports SVE and 'host' requires KVM which obtains
its supported bitmap from the host. So, we only need to initialize the
bitmap for 'max' with TCG. And, since 'max' should support all SVE
vector lengths we simply fill the bitmap. Future CPU types may have
less trivial maps though.

Signed-off-by: Andrew Jones <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
---
 target/arm/cpu.h   | 4 ++++
 target/arm/cpu64.c | 2 ++
 2 files changed, 6 insertions(+)

Comments

Richard Henderson Aug. 23, 2021, 5:43 p.m. UTC | #1

On 8/23/21 9:06 AM, Andrew Jones wrote:
> Allow CPUs that support SVE to specify which SVE vector lengths they
> support by setting them in this bitmap. Currently only the 'max' and
> 'host' CPU types supports SVE and 'host' requires KVM which obtains
> its supported bitmap from the host. So, we only need to initialize the
> bitmap for 'max' with TCG. And, since 'max' should support all SVE
> vector lengths we simply fill the bitmap. Future CPU types may have
> less trivial maps though.
> 
> Signed-off-by: Andrew Jones<[e-mail]>
> Reviewed-by: Philippe Mathieu-Daudé<[e-mail]>
> ---
>   target/arm/cpu.h   | 4 ++++
>   target/arm/cpu64.c | 2 ++
>   2 files changed, 6 insertions(+)

Reviewed-by: Richard Henderson <[e-mail]>

r~

Patch

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 9f0a5f84d503..cc645b57421f 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1019,9 +1019,13 @@  struct ARMCPU {
      * While processing properties during initialization, corresponding
      * sve_vq_init bits are set for bits in sve_vq_map that have been
      * set by properties.
+     *
+     * Bits set in sve_vq_supported represent valid vector lengths for
+     * the CPU type.
      */
     DECLARE_BITMAP(sve_vq_map, ARM_MAX_VQ);
     DECLARE_BITMAP(sve_vq_init, ARM_MAX_VQ);
+    DECLARE_BITMAP(sve_vq_supported, ARM_MAX_VQ);
 
     /* Generic timer counter frequency, in Hz */
     uint64_t gt_cntfrq_hz;
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index c690318a9b63..eb9318c83b74 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -840,6 +840,8 @@  static void aarch64_max_initfn(Object *obj)
         /* Default to PAUTH on, with the architected algorithm. */
         qdev_property_add_static(DEVICE(obj), &arm_cpu_pauth_property);
         qdev_property_add_static(DEVICE(obj), &arm_cpu_pauth_impdef_property);
+
+        bitmap_fill(cpu->sve_vq_supported, ARM_MAX_VQ);
     }
 
     aarch64_add_sve_properties(obj);