[RESEND,06/13] KVM: x86: Move #GP injection for VMware into x86_emulate_instruction()
diff mbox series

Message ID 20190823010709.24879-7-sean.j.christopherson@intel.com
State New
Headers show
Series
  • KVM: x86: Remove emulation_result enums
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Commit Message

Sean Christopherson Aug. 23, 2019, 1:07 a.m. UTC
Immediately inject a #GP when VMware emulation fails and return
EMULATE_DONE instead of propagating EMULATE_FAIL up the stack.  This
helps pave the way for removing EMULATE_FAIL altogether.

Rename EMULTYPE_VMWARE to EMULTYPE_VMWARE_GP to help document why a #GP
is injected on emulation failure.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/svm.c              |  9 ++-------
 arch/x86/kvm/vmx/vmx.c          |  9 ++-------
 arch/x86/kvm/x86.c              | 14 +++++++++-----
 4 files changed, 14 insertions(+), 20 deletions(-)

Comments

Vitaly Kuznetsov Aug. 23, 2019, 12:27 p.m. UTC | #1
Sean Christopherson <sean.j.christopherson@intel.com> writes:

> Immediately inject a #GP when VMware emulation fails and return
> EMULATE_DONE instead of propagating EMULATE_FAIL up the stack.  This
> helps pave the way for removing EMULATE_FAIL altogether.
>
> Rename EMULTYPE_VMWARE to EMULTYPE_VMWARE_GP to help document why a #GP
> is injected on emulation failure.

Hm, maybe it's just me but I would've assumed _GP suffix means 'called
from #GP intercept' and not '#GP is injected on failure'. This is no
different here because we only do #GP intercepts for vmware backdoor
emulation and this emulation only happens on #GP.

>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  arch/x86/include/asm/kvm_host.h |  2 +-
>  arch/x86/kvm/svm.c              |  9 ++-------
>  arch/x86/kvm/vmx/vmx.c          |  9 ++-------
>  arch/x86/kvm/x86.c              | 14 +++++++++-----
>  4 files changed, 14 insertions(+), 20 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index dd6bd9ed0839..d1d5b5ca1195 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1318,7 +1318,7 @@ enum emulation_result {
>  #define EMULTYPE_TRAP_UD	    (1 << 1)
>  #define EMULTYPE_SKIP		    (1 << 2)
>  #define EMULTYPE_ALLOW_RETRY	    (1 << 3)
> -#define EMULTYPE_VMWARE		    (1 << 5)
> +#define EMULTYPE_VMWARE_GP	    (1 << 5)
>  int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
>  int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
>  					void *insn, int insn_len);
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index b96a119690f4..97562c2c8b7b 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2768,7 +2768,6 @@ static int gp_interception(struct vcpu_svm *svm)
>  {
>  	struct kvm_vcpu *vcpu = &svm->vcpu;
>  	u32 error_code = svm->vmcb->control.exit_info_1;
> -	int er;
>  
>  	WARN_ON_ONCE(!enable_vmware_backdoor);
>  
> @@ -2776,12 +2775,8 @@ static int gp_interception(struct vcpu_svm *svm)
>  		kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
>  		return 1;
>  	}
> -	er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
> -	if (er == EMULATE_USER_EXIT)
> -		return 0;
> -	else if (er != EMULATE_DONE)
> -		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> -	return 1;
> +	return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
> +						EMULATE_USER_EXIT;
>  }
>  
>  static bool is_erratum_383(void)
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3ee0dd304bc7..25410c58c758 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4492,7 +4492,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
>  	u32 intr_info, ex_no, error_code;
>  	unsigned long cr2, rip, dr6;
>  	u32 vect_info;
> -	enum emulation_result er;
>  
>  	vect_info = vmx->idt_vectoring_info;
>  	intr_info = vmx->exit_intr_info;
> @@ -4514,12 +4513,8 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
>  			kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
>  			return 1;
>  		}
> -		er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
> -		if (er == EMULATE_USER_EXIT)
> -			return 0;
> -		else if (er != EMULATE_DONE)
> -			kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> -		return 1;
> +		return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
> +							EMULATE_USER_EXIT;
>  	}
>  
>  	/*
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e0f0e14d8fac..228ca71d5b01 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6210,8 +6210,10 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
>  	++vcpu->stat.insn_emulation_fail;
>  	trace_kvm_emulate_insn_failed(vcpu);
>  
> -	if (emulation_type & EMULTYPE_VMWARE)
> -		return EMULATE_FAIL;
> +	if (emulation_type & EMULTYPE_VMWARE_GP) {
> +		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> +		return EMULATE_DONE;
> +	}
>  
>  	kvm_queue_exception(vcpu, UD_VECTOR);
>  
> @@ -6543,9 +6545,11 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
>  		}
>  	}
>  
> -	if ((emulation_type & EMULTYPE_VMWARE) &&
> -	    !is_vmware_backdoor_opcode(ctxt))
> -		return EMULATE_FAIL;
> +	if ((emulation_type & EMULTYPE_VMWARE_GP) &&
> +	    !is_vmware_backdoor_opcode(ctxt)) {
> +		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> +		return EMULATE_DONE;
> +	}
>  
>  	if (emulation_type & EMULTYPE_SKIP) {
>  		kvm_rip_write(vcpu, ctxt->_eip);

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Liran Alon Aug. 23, 2019, 1:30 p.m. UTC | #2
> On 23 Aug 2019, at 4:07, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> 
> Immediately inject a #GP when VMware emulation fails and return
> EMULATE_DONE instead of propagating EMULATE_FAIL up the stack.  This
> helps pave the way for removing EMULATE_FAIL altogether.
> 
> Rename EMULTYPE_VMWARE to EMULTYPE_VMWARE_GP to help document why a #GP
> is injected on emulation failure.

I would rephrase to say that this rename is in order to document that the x86 emulator is called to handle
VMware #GP interception. In theory, VMware could have also added weird behaviour
to #UD interception as-well. :P

Besides minor comments inline below:
Reviewed-by: Liran Alon <liran.alon@oracle.com>

-Liran

> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h |  2 +-
> arch/x86/kvm/svm.c              |  9 ++-------
> arch/x86/kvm/vmx/vmx.c          |  9 ++-------
> arch/x86/kvm/x86.c              | 14 +++++++++-----
> 4 files changed, 14 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index dd6bd9ed0839..d1d5b5ca1195 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1318,7 +1318,7 @@ enum emulation_result {
> #define EMULTYPE_TRAP_UD	    (1 << 1)
> #define EMULTYPE_SKIP		    (1 << 2)
> #define EMULTYPE_ALLOW_RETRY	    (1 << 3)
> -#define EMULTYPE_VMWARE		    (1 << 5)
> +#define EMULTYPE_VMWARE_GP	    (1 << 5)
> int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
> int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
> 					void *insn, int insn_len);
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index b96a119690f4..97562c2c8b7b 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2768,7 +2768,6 @@ static int gp_interception(struct vcpu_svm *svm)
> {
> 	struct kvm_vcpu *vcpu = &svm->vcpu;
> 	u32 error_code = svm->vmcb->control.exit_info_1;
> -	int er;
> 
> 	WARN_ON_ONCE(!enable_vmware_backdoor);
> 
> @@ -2776,12 +2775,8 @@ static int gp_interception(struct vcpu_svm *svm)
> 		kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
> 		return 1;
> 	}
> -	er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
> -	if (er == EMULATE_USER_EXIT)
> -		return 0;
> -	else if (er != EMULATE_DONE)
> -		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> -	return 1;
> +	return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
> +						EMULATE_USER_EXIT;
> }
> 
> static bool is_erratum_383(void)
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3ee0dd304bc7..25410c58c758 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4492,7 +4492,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
> 	u32 intr_info, ex_no, error_code;
> 	unsigned long cr2, rip, dr6;
> 	u32 vect_info;
> -	enum emulation_result er;
> 
> 	vect_info = vmx->idt_vectoring_info;
> 	intr_info = vmx->exit_intr_info;
> @@ -4514,12 +4513,8 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
> 			kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
> 			return 1;
> 		}
> -		er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
> -		if (er == EMULATE_USER_EXIT)
> -			return 0;
> -		else if (er != EMULATE_DONE)
> -			kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> -		return 1;
> +		return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
> +							EMULATE_USER_EXIT;
> 	}
> 
> 	/*
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e0f0e14d8fac..228ca71d5b01 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6210,8 +6210,10 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
> 	++vcpu->stat.insn_emulation_fail;
> 	trace_kvm_emulate_insn_failed(vcpu);
> 
> -	if (emulation_type & EMULTYPE_VMWARE)
> -		return EMULATE_FAIL;
> +	if (emulation_type & EMULTYPE_VMWARE_GP) {
> +		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);

I would add here a comment explaining why you can assume #GP error-code is 0.
i.e. Explain that’s because VMware #GP interception is only related to IN{S}, OUT{S} and RDPMC
instructions which all of them raise #GP with error-code of 0.

> +		return EMULATE_DONE;
> +	}
> 
> 	kvm_queue_exception(vcpu, UD_VECTOR);
> 
> @@ -6543,9 +6545,11 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
> 		}
> 	}
> 
> -	if ((emulation_type & EMULTYPE_VMWARE) &&
> -	    !is_vmware_backdoor_opcode(ctxt))
> -		return EMULATE_FAIL;
> +	if ((emulation_type & EMULTYPE_VMWARE_GP) &&
> +	    !is_vmware_backdoor_opcode(ctxt)) {
> +		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);

Same here.

> +		return EMULATE_DONE;
> +	}
> 
> 	if (emulation_type & EMULTYPE_SKIP) {
> 		kvm_rip_write(vcpu, ctxt->_eip);
> -- 
> 2.22.0
>

Patch
diff mbox series

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index dd6bd9ed0839..d1d5b5ca1195 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1318,7 +1318,7 @@  enum emulation_result {
 #define EMULTYPE_TRAP_UD	    (1 << 1)
 #define EMULTYPE_SKIP		    (1 << 2)
 #define EMULTYPE_ALLOW_RETRY	    (1 << 3)
-#define EMULTYPE_VMWARE		    (1 << 5)
+#define EMULTYPE_VMWARE_GP	    (1 << 5)
 int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
 int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
 					void *insn, int insn_len);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b96a119690f4..97562c2c8b7b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2768,7 +2768,6 @@  static int gp_interception(struct vcpu_svm *svm)
 {
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 	u32 error_code = svm->vmcb->control.exit_info_1;
-	int er;
 
 	WARN_ON_ONCE(!enable_vmware_backdoor);
 
@@ -2776,12 +2775,8 @@  static int gp_interception(struct vcpu_svm *svm)
 		kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
 		return 1;
 	}
-	er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
-	if (er == EMULATE_USER_EXIT)
-		return 0;
-	else if (er != EMULATE_DONE)
-		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-	return 1;
+	return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
+						EMULATE_USER_EXIT;
 }
 
 static bool is_erratum_383(void)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 3ee0dd304bc7..25410c58c758 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4492,7 +4492,6 @@  static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 	u32 intr_info, ex_no, error_code;
 	unsigned long cr2, rip, dr6;
 	u32 vect_info;
-	enum emulation_result er;
 
 	vect_info = vmx->idt_vectoring_info;
 	intr_info = vmx->exit_intr_info;
@@ -4514,12 +4513,8 @@  static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 			kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
 			return 1;
 		}
-		er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
-		if (er == EMULATE_USER_EXIT)
-			return 0;
-		else if (er != EMULATE_DONE)
-			kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-		return 1;
+		return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
+							EMULATE_USER_EXIT;
 	}
 
 	/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e0f0e14d8fac..228ca71d5b01 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6210,8 +6210,10 @@  static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
 	++vcpu->stat.insn_emulation_fail;
 	trace_kvm_emulate_insn_failed(vcpu);
 
-	if (emulation_type & EMULTYPE_VMWARE)
-		return EMULATE_FAIL;
+	if (emulation_type & EMULTYPE_VMWARE_GP) {
+		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+		return EMULATE_DONE;
+	}
 
 	kvm_queue_exception(vcpu, UD_VECTOR);
 
@@ -6543,9 +6545,11 @@  int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 		}
 	}
 
-	if ((emulation_type & EMULTYPE_VMWARE) &&
-	    !is_vmware_backdoor_opcode(ctxt))
-		return EMULATE_FAIL;
+	if ((emulation_type & EMULTYPE_VMWARE_GP) &&
+	    !is_vmware_backdoor_opcode(ctxt)) {
+		kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+		return EMULATE_DONE;
+	}
 
 	if (emulation_type & EMULTYPE_SKIP) {
 		kvm_rip_write(vcpu, ctxt->_eip);