KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

[PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Sean Christopherson 3 months, 1 week ago

Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
code that fills the exit reason and CPU when KVM encounters a VM-Exit that
KVM doesn't know how to handle.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/svm/svm.c          |  7 +------
 arch/x86/kvm/vmx/tdx.c          |  6 +-----
 arch/x86/kvm/vmx/vmx.c          |  9 +--------
 arch/x86/kvm/x86.c              | 12 ++++++++++++
 5 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 48598d017d6f..4fbe4b7ce1da 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2167,6 +2167,7 @@ void __kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu,
 void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu);
 
 void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa);
+void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason);
 
 void kvm_enable_efer_bits(u64);
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f14709a511aa..83e0d4d5f4c5 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3451,13 +3451,8 @@ static bool svm_check_exit_valid(u64 exit_code)
 
 static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
 {
-	vcpu_unimpl(vcpu, "svm: unexpected exit reason 0x%llx\n", exit_code);
 	dump_vmcb(vcpu);
-	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
-	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
-	vcpu->run->internal.ndata = 2;
-	vcpu->run->internal.data[0] = exit_code;
-	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
+	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
 	return 0;
 }
 
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 326db9b9c567..079d9f13eddb 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -2145,11 +2145,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
 	}
 
 unhandled_exit:
-	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
-	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
-	vcpu->run->internal.ndata = 2;
-	vcpu->run->internal.data[0] = vp_enter_ret;
-	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
+	kvm_prepare_unexpected_reason_exit(vcpu, vp_enter_ret);
 	return 0;
 }
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1021d3b65ea0..08f7957ed4c3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6642,15 +6642,8 @@ static int __vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 	return kvm_vmx_exit_handlers[exit_handler_index](vcpu);
 
 unexpected_vmexit:
-	vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n",
-		    exit_reason.full);
 	dump_vmcs(vcpu);
-	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
-	vcpu->run->internal.suberror =
-			KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
-	vcpu->run->internal.ndata = 2;
-	vcpu->run->internal.data[0] = exit_reason.full;
-	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
+	kvm_prepare_unexpected_reason_exit(vcpu, exit_reason.full);
 	return 0;
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b4b5d2d09634..c826cd05228a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9110,6 +9110,18 @@ void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa)
 }
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_event_vectoring_exit);
 
+void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason)
+{
+	vcpu_unimpl(vcpu, "unexpected exit reason 0x%llx\n", exit_reason);
+
+	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
+	vcpu->run->internal.ndata = 2;
+	vcpu->run->internal.data[0] = exit_reason;
+	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
+}
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_unexpected_reason_exit);
+
 static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
 {
 	struct kvm *kvm = vcpu->kvm;

base-commit: 4cc167c50eb19d44ac7e204938724e685e3d8057
-- 
2.51.1.930.gacf6e81ea2-goog

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Sean Christopherson 3 months ago

On Thu, 30 Oct 2025 11:50:03 -0700, Sean Christopherson wrote:
> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
> 
> 

Applied to kvm-x86 misc, thanks!

[1/1] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits
      https://github.com/kvm-x86/linux/commit/65a70164aba7

--
https://github.com/kvm-x86/linux/tree/next

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Binbin Wu 3 months ago


On 10/31/2025 2:50 AM, Sean Christopherson wrote:
> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Xiaoyao Li 3 months ago

On 10/31/2025 2:50 AM, Sean Christopherson wrote:
> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>

> ---
>   arch/x86/include/asm/kvm_host.h |  1 +
>   arch/x86/kvm/svm/svm.c          |  7 +------
>   arch/x86/kvm/vmx/tdx.c          |  6 +-----
>   arch/x86/kvm/vmx/vmx.c          |  9 +--------
>   arch/x86/kvm/x86.c              | 12 ++++++++++++
>   5 files changed, 16 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 48598d017d6f..4fbe4b7ce1da 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -2167,6 +2167,7 @@ void __kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu,
>   void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu);
>   
>   void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa);
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason);
>   
>   void kvm_enable_efer_bits(u64);
>   bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index f14709a511aa..83e0d4d5f4c5 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3451,13 +3451,8 @@ static bool svm_check_exit_valid(u64 exit_code)
>   
>   static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
>   {
> -	vcpu_unimpl(vcpu, "svm: unexpected exit reason 0x%llx\n", exit_code);
>   	dump_vmcb(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_code;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
>   	return 0;
>   }
>   
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 326db9b9c567..079d9f13eddb 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -2145,11 +2145,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
>   	}
>   
>   unhandled_exit:
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = vp_enter_ret;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, vp_enter_ret);
>   	return 0;
>   }
>   
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 1021d3b65ea0..08f7957ed4c3 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6642,15 +6642,8 @@ static int __vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>   	return kvm_vmx_exit_handlers[exit_handler_index](vcpu);
>   
>   unexpected_vmexit:
> -	vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n",
> -		    exit_reason.full);
>   	dump_vmcs(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror =
> -			KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_reason.full;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_reason.full);
>   	return 0;
>   }
>   
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b4b5d2d09634..c826cd05228a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9110,6 +9110,18 @@ void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa)
>   }
>   EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_event_vectoring_exit);
>   
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason)
> +{
> +	vcpu_unimpl(vcpu, "unexpected exit reason 0x%llx\n", exit_reason);
> +
> +	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> +	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> +	vcpu->run->internal.ndata = 2;
> +	vcpu->run->internal.data[0] = exit_reason;
> +	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +}
> +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_unexpected_reason_exit);
> +
>   static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
>   {
>   	struct kvm *kvm = vcpu->kvm;
> 
> base-commit: 4cc167c50eb19d44ac7e204938724e685e3d8057

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Yosry Ahmed 3 months ago

On Thu, Oct 30, 2025 at 11:50:03AM -0700, Sean Christopherson wrote:
> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/include/asm/kvm_host.h |  1 +
>  arch/x86/kvm/svm/svm.c          |  7 +------
>  arch/x86/kvm/vmx/tdx.c          |  6 +-----
>  arch/x86/kvm/vmx/vmx.c          |  9 +--------
>  arch/x86/kvm/x86.c              | 12 ++++++++++++
>  5 files changed, 16 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 48598d017d6f..4fbe4b7ce1da 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -2167,6 +2167,7 @@ void __kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu,
>  void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu);
>  
>  void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa);
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason);
>  
>  void kvm_enable_efer_bits(u64);
>  bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index f14709a511aa..83e0d4d5f4c5 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3451,13 +3451,8 @@ static bool svm_check_exit_valid(u64 exit_code)
>  
>  static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
>  {
> -	vcpu_unimpl(vcpu, "svm: unexpected exit reason 0x%llx\n", exit_code);
>  	dump_vmcb(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_code;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
>  	return 0;
>  }

We can probably drop svm_handle_invalid_exit() entirely now, but looks
good either way:

Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>

>  
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 326db9b9c567..079d9f13eddb 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -2145,11 +2145,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
>  	}
>  
>  unhandled_exit:
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = vp_enter_ret;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, vp_enter_ret);
>  	return 0;
>  }
>  
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 1021d3b65ea0..08f7957ed4c3 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6642,15 +6642,8 @@ static int __vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>  	return kvm_vmx_exit_handlers[exit_handler_index](vcpu);
>  
>  unexpected_vmexit:
> -	vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n",
> -		    exit_reason.full);
>  	dump_vmcs(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror =
> -			KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_reason.full;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_reason.full);
>  	return 0;
>  }
>  
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b4b5d2d09634..c826cd05228a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9110,6 +9110,18 @@ void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa)
>  }
>  EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_event_vectoring_exit);
>  
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason)
> +{
> +	vcpu_unimpl(vcpu, "unexpected exit reason 0x%llx\n", exit_reason);
> +
> +	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> +	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> +	vcpu->run->internal.ndata = 2;
> +	vcpu->run->internal.data[0] = exit_reason;
> +	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +}
> +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_unexpected_reason_exit);
> +
>  static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
>  {
>  	struct kvm *kvm = vcpu->kvm;
> 
> base-commit: 4cc167c50eb19d44ac7e204938724e685e3d8057
> -- 
> 2.51.1.930.gacf6e81ea2-goog
>

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Sean Christopherson 3 months ago

On Mon, Nov 03, 2025, Yosry Ahmed wrote:
> On Thu, Oct 30, 2025 at 11:50:03AM -0700, Sean Christopherson wrote:
> > Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> > code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> > KVM doesn't know how to handle.
> > 
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> >  arch/x86/include/asm/kvm_host.h |  1 +
> >  arch/x86/kvm/svm/svm.c          |  7 +------
> >  arch/x86/kvm/vmx/tdx.c          |  6 +-----
> >  arch/x86/kvm/vmx/vmx.c          |  9 +--------
> >  arch/x86/kvm/x86.c              | 12 ++++++++++++
> >  5 files changed, 16 insertions(+), 19 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 48598d017d6f..4fbe4b7ce1da 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -2167,6 +2167,7 @@ void __kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu,
> >  void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu);
> >  
> >  void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa);
> > +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason);
> >  
> >  void kvm_enable_efer_bits(u64);
> >  bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index f14709a511aa..83e0d4d5f4c5 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -3451,13 +3451,8 @@ static bool svm_check_exit_valid(u64 exit_code)
> >  
> >  static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
> >  {
> > -	vcpu_unimpl(vcpu, "svm: unexpected exit reason 0x%llx\n", exit_code);
> >  	dump_vmcb(vcpu);
> > -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> > -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> > -	vcpu->run->internal.ndata = 2;
> > -	vcpu->run->internal.data[0] = exit_code;
> > -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> > +	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
> >  	return 0;
> >  }
> 
> We can probably drop svm_handle_invalid_exit() entirely now

Hmm, yeah.  I'll do so in a separate follow-up, as I want to do more than just
fold svm_handle_invalid_exit() into svm_invoke_exit_handler().

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Gupta, Pankaj 3 months, 1 week ago

> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>

> ---
>   arch/x86/include/asm/kvm_host.h |  1 +
>   arch/x86/kvm/svm/svm.c          |  7 +------
>   arch/x86/kvm/vmx/tdx.c          |  6 +-----
>   arch/x86/kvm/vmx/vmx.c          |  9 +--------
>   arch/x86/kvm/x86.c              | 12 ++++++++++++
>   5 files changed, 16 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 48598d017d6f..4fbe4b7ce1da 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -2167,6 +2167,7 @@ void __kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu,
>   void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu);
>   
>   void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa);
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason);
>   
>   void kvm_enable_efer_bits(u64);
>   bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index f14709a511aa..83e0d4d5f4c5 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3451,13 +3451,8 @@ static bool svm_check_exit_valid(u64 exit_code)
>   
>   static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
>   {
> -	vcpu_unimpl(vcpu, "svm: unexpected exit reason 0x%llx\n", exit_code);
>   	dump_vmcb(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_code;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
>   	return 0;
>   }
>   
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 326db9b9c567..079d9f13eddb 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -2145,11 +2145,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
>   	}
>   
>   unhandled_exit:
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = vp_enter_ret;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, vp_enter_ret);
>   	return 0;
>   }
>   
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 1021d3b65ea0..08f7957ed4c3 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6642,15 +6642,8 @@ static int __vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>   	return kvm_vmx_exit_handlers[exit_handler_index](vcpu);
>   
>   unexpected_vmexit:
> -	vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n",
> -		    exit_reason.full);
>   	dump_vmcs(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror =
> -			KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_reason.full;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_reason.full);
>   	return 0;
>   }
>   
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b4b5d2d09634..c826cd05228a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9110,6 +9110,18 @@ void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa)
>   }
>   EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_event_vectoring_exit);
>   
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason)
> +{
> +	vcpu_unimpl(vcpu, "unexpected exit reason 0x%llx\n", exit_reason);
> +
> +	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> +	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> +	vcpu->run->internal.ndata = 2;
> +	vcpu->run->internal.data[0] = exit_reason;
> +	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +}
> +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_unexpected_reason_exit);
> +
>   static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
>   {
>   	struct kvm *kvm = vcpu->kvm;
>
> base-commit: 4cc167c50eb19d44ac7e204938724e685e3d8057

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Huang, Kai 3 months, 1 week ago

On Thu, 2025-10-30 at 11:50 -0700, Sean Christopherson wrote:
> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> 

Acked-by: Kai Huang <kai.huang@intel.com>

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Yao Yuan 3 months, 1 week ago

On Thu, Oct 30, 2025 at 11:50:03AM +0800, Sean Christopherson wrote:
> Add and use a helper, kvm_prepare_unexpected_reason_exit(), to dedup the
> code that fills the exit reason and CPU when KVM encounters a VM-Exit that
> KVM doesn't know how to handle.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/include/asm/kvm_host.h |  1 +
>  arch/x86/kvm/svm/svm.c          |  7 +------
>  arch/x86/kvm/vmx/tdx.c          |  6 +-----
>  arch/x86/kvm/vmx/vmx.c          |  9 +--------
>  arch/x86/kvm/x86.c              | 12 ++++++++++++
>  5 files changed, 16 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 48598d017d6f..4fbe4b7ce1da 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -2167,6 +2167,7 @@ void __kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu,
>  void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu);
>
>  void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa);
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason);
>
>  void kvm_enable_efer_bits(u64);
>  bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index f14709a511aa..83e0d4d5f4c5 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3451,13 +3451,8 @@ static bool svm_check_exit_valid(u64 exit_code)
>
>  static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
>  {
> -	vcpu_unimpl(vcpu, "svm: unexpected exit reason 0x%llx\n", exit_code);
>  	dump_vmcb(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_code;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
>  	return 0;
>  }
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 326db9b9c567..079d9f13eddb 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -2145,11 +2145,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
>  	}
>
>  unhandled_exit:
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = vp_enter_ret;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, vp_enter_ret);
>  	return 0;
>  }
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 1021d3b65ea0..08f7957ed4c3 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6642,15 +6642,8 @@ static int __vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>  	return kvm_vmx_exit_handlers[exit_handler_index](vcpu);
>
>  unexpected_vmexit:
> -	vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n",
> -		    exit_reason.full);
>  	dump_vmcs(vcpu);
> -	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> -	vcpu->run->internal.suberror =
> -			KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> -	vcpu->run->internal.ndata = 2;
> -	vcpu->run->internal.data[0] = exit_reason.full;
> -	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_reason.full);
>  	return 0;
>  }
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b4b5d2d09634..c826cd05228a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9110,6 +9110,18 @@ void kvm_prepare_event_vectoring_exit(struct kvm_vcpu *vcpu, gpa_t gpa)
>  }
>  EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_event_vectoring_exit);
>
> +void kvm_prepare_unexpected_reason_exit(struct kvm_vcpu *vcpu, u64 exit_reason)
> +{
> +	vcpu_unimpl(vcpu, "unexpected exit reason 0x%llx\n", exit_reason);

I like the dedup, and this brings above for tdx which not
before. Just one small thing: Will it be better if keep the
"vmx"/"svm" hint as before and plus the "tdx" hint yet ?

Reviewed-by: Yao Yuan <yaoyuan@linux.alibaba.com>

> +
> +	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> +	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
> +	vcpu->run->internal.ndata = 2;
> +	vcpu->run->internal.data[0] = exit_reason;
> +	vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
> +}
> +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_prepare_unexpected_reason_exit);
> +
>  static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
>  {
>  	struct kvm *kvm = vcpu->kvm;
>
> base-commit: 4cc167c50eb19d44ac7e204938724e685e3d8057
> --
> 2.51.1.930.gacf6e81ea2-goog
>

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Sean Christopherson 3 months, 1 week ago

On Fri, Oct 31, 2025, Yao Yuan wrote:
> On Thu, Oct 30, 2025 at 11:50:03AM +0800, Sean Christopherson wrote:
> I like the dedup, and this brings above for tdx which not
> before. Just one small thing: Will it be better if keep the
> "vmx"/"svm" hint as before and plus the "tdx" hint yet ?

It'd be nice to have, but I honestly don't think it's worth going out of our
way to capture that information.  If someone can't disambiguate "kvm" to mean
"vmx/tdx" vs. "svm" based on the host, they've got bigger problems.

And as for "vmx" vs. "tdx", I really hope that's not meaningful information for
users, e.g. the printks are ratelimited, and users should really be gleaning
information from the VMM instance, not from dmesg.

Re: [PATCH] KVM: x86: Add a helper to dedup reporting of unhandled VM-Exits

Posted by Yao Yuan 3 months, 1 week ago

On Fri, Oct 31, 2025 at 10:01:38AM +0800, Sean Christopherson wrote:
> On Fri, Oct 31, 2025, Yao Yuan wrote:
> > On Thu, Oct 30, 2025 at 11:50:03AM +0800, Sean Christopherson wrote:
> > I like the dedup, and this brings above for tdx which not
> > before. Just one small thing: Will it be better if keep the
> > "vmx"/"svm" hint as before and plus the "tdx" hint yet ?
>
> It'd be nice to have, but I honestly don't think it's worth going out of our
> way to capture that information.  If someone can't disambiguate "kvm" to mean
> "vmx/tdx" vs. "svm" based on the host, they've got bigger problems.
>
> And as for "vmx" vs. "tdx", I really hope that's not meaningful information for
> users, e.g. the printks are ratelimited, and users should really be gleaning
> information from the VMM instance, not from dmesg.

thanks for your reply, Good point on printks are ratelimited!

Reviewed-by: yaoyuan@linux.alibaba.com