Re: [PATCH v5 10/11] target/i386/kvm: Clean up error handling in kvm_arch_init()

Paolo Bonzini
2024-12-24T15:53:42Z

On 11/6/24 04:07, Zhao Liu wrote:
> Currently, there're following incorrect error handling cases in
> kvm_arch_init():
> * Missed to handle failure of kvm_get_supported_feature_msrs().
> * Missed to return when kvm_vm_enable_disable_exits() fails.

At least in these two cases I think it was intentional to avoid hard
failures. It's probably not a very likely case and I think your patch
is overall a good idea.

Paolo

> * MSR filter related cases called exit() directly instead of returning
> to kvm_init(). (The caller of kvm_arch_init() - kvm_init() - needs to
> know if kvm_arch_init() fails in order to perform cleanup).
>
> Fix the above cases.
>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> Reviewed-by: Zide Chen <zide.chen@intel.com>
> ---
> v5: cleaned up kvm_vm_enable_energy_msrs().
> v3: new commit.
> ---
> target/i386/kvm/kvm.c | 25 ++++++++++++++++---------
> 1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index 69825b53b6da..013c0359acbe 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -3147,7 +3147,7 @@ static int kvm_vm_enable_userspace_msr(KVMState *s)
> return 0;
> }
>
> -static void kvm_vm_enable_energy_msrs(KVMState *s)
> +static int kvm_vm_enable_energy_msrs(KVMState *s)
> {
> int ret;
>
> @@ -3157,7 +3157,7 @@ static void kvm_vm_enable_energy_msrs(KVMState *s)
> if (ret < 0) {
> error_report("Could not install MSR_RAPL_POWER_UNIT handler: %s",
> strerror(-ret));
> - exit(1);
> + return ret;
> }
>
> ret = kvm_filter_msr(s, MSR_PKG_POWER_LIMIT,
> @@ -3165,7 +3165,7 @@ static void kvm_vm_enable_energy_msrs(KVMState *s)
> if (ret < 0) {
> error_report("Could not install MSR_PKG_POWER_LIMIT handler: %s",
> strerror(-ret));
> - exit(1);
> + return ret;
> }
>
> ret = kvm_filter_msr(s, MSR_PKG_POWER_INFO,
> @@ -3173,17 +3173,17 @@ static void kvm_vm_enable_energy_msrs(KVMState *s)
> if (ret < 0) {
> error_report("Could not install MSR_PKG_POWER_INFO handler: %s",
> strerror(-ret));
> - exit(1);
> + return ret;
> }
> ret = kvm_filter_msr(s, MSR_PKG_ENERGY_STATUS,
> kvm_rdmsr_pkg_energy_status, NULL);
> if (ret < 0) {
> error_report("Could not install MSR_PKG_ENERGY_STATUS handler: %s",
> strerror(-ret));
> - exit(1);
> + return ret;
> }
> }
> - return;
> + return 0;
> }
>
> int kvm_arch_init(MachineState *ms, KVMState *s)
> @@ -3250,7 +3250,10 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
> return ret;
> }
>
> - kvm_get_supported_feature_msrs(s);
> + ret = kvm_get_supported_feature_msrs(s);
> + if (ret < 0) {
> + return ret;
> + }
>
> uname(&utsname);
> lm_capable_kernel = strcmp(utsname.machine, "x86_64") == 0;
> @@ -3286,6 +3289,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
> if (ret < 0) {
> error_report("kvm: guest stopping CPU not supported: %s",
> strerror(-ret));
> + return ret;
> }
> }
>
> @@ -3317,12 +3321,15 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
> }
>
> if (s->msr_energy.enable == true) {
> - kvm_vm_enable_energy_msrs(s);
> + ret = kvm_vm_enable_energy_msrs(s);
> + if (ret < 0) {
> + return ret;
> + }
>
> ret = kvm_msr_energy_thread_init(s, ms);
> if (ret < 0) {
> error_report("kvm : error RAPL feature requirement not met");
> - exit(1);
> + return ret;
> }
> }
> }