Re: [PATCH 3/6] target/arm: Better describe PMU depends on TCG or HVF

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 6/30/25 6:09 AM, Philippe Mathieu-Daudé wrote:
> Simplify PMU logic by rewriting '!KVM' as 'TCG || HVF'
> (ignoring QTest, because vCPUs are not available there).
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   target/arm/cpu.c     |  2 +-
>   target/arm/machine.c | 10 +++++-----
>   2 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index b6a8ba83a46..0311ff315fe 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -2352,7 +2352,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
>       if (arm_feature(env, ARM_FEATURE_PMU)) {
>           pmu_init(cpu);
>   
> -        if (!kvm_enabled()) {
> +        if (tcg_enabled() || hvf_enabled()) {
>               arm_register_pre_el_change_hook(cpu, &pmu_pre_el_change, 0);
>               arm_register_el_change_hook(cpu, &pmu_post_el_change, 0);
>           }
> diff --git a/target/arm/machine.c b/target/arm/machine.c
> index e442d485241..baa7ad25ca9 100644
> --- a/target/arm/machine.c
> +++ b/target/arm/machine.c
> @@ -1,7 +1,7 @@
>   #include "qemu/osdep.h"
>   #include "cpu.h"
>   #include "qemu/error-report.h"
> -#include "system/kvm.h"
> +#include "system/hvf.h"
>   #include "system/tcg.h"
>   #include "kvm_arm.h"
>   #include "internals.h"
> @@ -853,7 +853,7 @@ static int cpu_pre_save(void *opaque)
>   {
>       ARMCPU *cpu = opaque;
>   
> -    if (!kvm_enabled()) {
> +    if (tcg_enabled() || hvf_enabled()) {
>           pmu_op_start(&cpu->env);
>       }
>   
> @@ -888,7 +888,7 @@ static int cpu_post_save(void *opaque)
>   {
>       ARMCPU *cpu = opaque;
>   
> -    if (!kvm_enabled()) {
> +    if (tcg_enabled() || hvf_enabled()) {
>           pmu_op_finish(&cpu->env);
>       }
>   
> @@ -921,7 +921,7 @@ static int cpu_pre_load(void *opaque)
>        */
>       env->irq_line_state = UINT32_MAX;
>   
> -    if (!kvm_enabled()) {
> +    if (tcg_enabled() || hvf_enabled()) {
>           pmu_op_start(env);
>       }
>   
> @@ -1013,7 +1013,7 @@ static int cpu_post_load(void *opaque, int version_id)
>           }
>       }
>   
> -    if (!kvm_enabled()) {
> +    if (tcg_enabled() || hvf_enabled()) {
>           pmu_op_finish(env);
>       }
>   

If I understand correctly, this is supported for tcg and hvf, but not 
kvm, right?
I'm just a bit confused by commit description mentioning "simplify 
logic", which is more "make it explicit".

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>

Thanks,
Pierrick