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.
* 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;
}
}
}
--
2.34.1On 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;
> }
> }
> }
On Tue, Dec 24, 2024 at 04:53:36PM +0100, Paolo Bonzini wrote: > Date: Tue, 24 Dec 2024 16:53:36 +0100 > From: Paolo Bonzini <pbonzini@redhat.com> > Subject: Re: [PATCH v5 10/11] target/i386/kvm: Clean up error handling in > kvm_arch_init() > > 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. I have the idea to clean up the abort()/exit() in KVM and instead use @errp to handle failure cases. However, this would be a big change, so this patch only makes a small change, as a first step. Thanks, Zhao
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