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Re: [Qemu-arm] [PATCH v2 01/14] target/arm/cpu64: Ensure kvm really supp


From: Auger Eric
Subject: Re: [Qemu-arm] [PATCH v2 01/14] target/arm/cpu64: Ensure kvm really supports aarch64=off
Date: Tue, 25 Jun 2019 11:35:12 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

Hi Drew,

On 6/21/19 6:34 PM, Andrew Jones wrote:
> If -cpu <cpu>,aarch64=off is used then KVM must also be used, and it
> and the host must support running the vcpu in 32-bit mode. Also, if
> -cpu <cpu>,aarch64=on is used, then it doesn't matter if kvm is
> enabled or not.
> 
> Signed-off-by: Andrew Jones <address@hidden>


> ---
>  target/arm/cpu64.c   | 12 ++++++------
>  target/arm/kvm64.c   | 11 +++++++++++
>  target/arm/kvm_arm.h | 14 ++++++++++++++
>  3 files changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
> index 1901997a0645..946994838d8a 100644
> --- a/target/arm/cpu64.c
> +++ b/target/arm/cpu64.c
> @@ -407,13 +407,13 @@ static void aarch64_cpu_set_aarch64(Object *obj, bool 
> value, Error **errp)
>       * restriction allows us to avoid fixing up functionality that assumes a
>       * uniform execution state like do_interrupt.
>       */> -    if (!kvm_enabled()) {
> -        error_setg(errp, "'aarch64' feature cannot be disabled "
> -                         "unless KVM is enabled");
> -        return;
> -    }
> -
>      if (value == false) {
> +        if (!kvm_enabled() || !kvm_arm_aarch32_supported(CPU(cpu))) {
> +            error_setg(errp, "'aarch64' feature cannot be disabled "
> +                             "unless KVM is enabled and 32-bit EL1 "
> +                             "is supported");
> +            return;
> +        }
>          unset_feature(&cpu->env, ARM_FEATURE_AARCH64);
>      } else {
>          set_feature(&cpu->env, ARM_FEATURE_AARCH64);
> diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
> index 22d19c9aec6f..45ccda589903 100644
> --- a/target/arm/kvm64.c
> +++ b/target/arm/kvm64.c
> @@ -24,7 +24,9 @@
>  #include "exec/gdbstub.h"
>  #include "sysemu/sysemu.h"
>  #include "sysemu/kvm.h"
> +#include "sysemu/kvm_int.h"
>  #include "kvm_arm.h"
> +#include "hw/boards.h"
>  #include "internals.h"
>  
>  static bool have_guest_debug;
> @@ -593,6 +595,15 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures 
> *ahcf)
>      return true;
>  }
>  
> +bool kvm_arm_aarch32_supported(CPUState *cpu)
> +{
> +    KVMState *s = KVM_STATE(current_machine->accelerator);
> +    int ret;
> +
> +    ret = kvm_check_extension(s, KVM_CAP_ARM_EL1_32BIT);
> +    return ret > 0;
nit: return kvm_check_extension() should be sufficient
> +}
> +
>  #define ARM_CPU_ID_MPIDR       3, 0, 0, 0, 5
>  
>  int kvm_arch_init_vcpu(CPUState *cs)
> diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
> index 2a07333c615f..812125f805a1 100644
> --- a/target/arm/kvm_arm.h
> +++ b/target/arm/kvm_arm.h
> @@ -207,6 +207,15 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures 
> *ahcf);
>   */
>  void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu);
>  
> +/**
> + * kvm_arm_aarch32_supported:
> + * @cs: CPUState
use kernel-doc comment style?
> + *
> + * Returns true if the KVM VCPU can enable AArch32 mode and false
> + * otherwise.
> + */
> +bool kvm_arm_aarch32_supported(CPUState *cs);
> +
>  /**
>   * kvm_arm_get_max_vm_ipa_size - Returns the number of bits in the
>   * IPA address space supported by KVM
> @@ -247,6 +256,11 @@ static inline void 
> kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
>      cpu->host_cpu_probe_failed = true;
>  }
>  
> +static inline bool kvm_arm_aarch32_supported(CPUState *cs)
> +{
> +    return false;
> +}
> +
>  static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
>  {
>      return -ENOENT;
> 
Reviewed-by: Eric Auger <address@hidden>

Thanks

Eric



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