Re: [PATCH 3/9] Implement GIF, clgi and stgi v2

[Joerg Roedel <joro@8bytes.org>]

On Fri, Sep 05, 2008 at 09:51:18AM +0200, Alexander Graf wrote:
> This patch implements the GIF flag and the clgi and stgi instructions that
> set this flag. Only if the flag is set (default), interrupts can be received by
> the CPU.
> 
> To keep the information about that somewhere, this patch adds a new hidden
> flags vector. that is used to store information that does not go into the
> vmcb, but is SVM specific.
> 
> v2 moves the hflags to x86 generic code
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  arch/x86/kvm/svm.c         |   50 +++++++++++++++++++++++++++++++++++++++++--
>  include/asm-x86/kvm_host.h |    3 ++
>  2 files changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index d9b18cc..a6d9a74 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -602,6 +602,8 @@ static void init_vmcb(struct vcpu_svm *svm)
>  		save->cr4 = 0;
>  	}
>  	force_new_asid(&svm->vcpu);
> +
> +	svm->vcpu.arch.hflags = HF_GIF_MASK;
>  }
>  
>  static int svm_vcpu_reset(struct kvm_vcpu *vcpu)
> @@ -1139,6 +1141,44 @@ static int vmmcall_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
>  	return 1;
>  }
>  
> +static int stgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
> +{
> +	if (svm->vmcb->save.cpl) {
> +		printk(KERN_ERR "%s: invalid cpl 0x%x at ip 0x%lx\n",
> +		       __func__, svm->vmcb->save.cpl, kvm_rip_read(&svm->vcpu));
> +		kvm_queue_exception(&svm->vcpu, GP_VECTOR);
> +		return 1;
> +	}

You need to check EFER.SVME here.

> +
> +	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
> +	skip_emulated_instruction(&svm->vcpu);
> +
> +	svm->vcpu.arch.hflags |= HF_GIF_MASK;
> +
> +	return 1;
> +}
> +
> +static int clgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
> +{
> +	if (svm->vmcb->save.cpl) {
> +		printk(KERN_ERR "%s: invalid cpl 0x%x at ip 0x%lx\n",
> +		       __func__, svm->vmcb->save.cpl, kvm_rip_read(&svm->vcpu));
> +		kvm_queue_exception(&svm->vcpu, GP_VECTOR);
> +		return 1;
> +	}

And here too. I suggest implementing a function which checks EFER.SVME
and CPL and call it in every emulated SVM instruction.

> +
> +	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
> +	skip_emulated_instruction(&svm->vcpu);
> +
> +	svm->vcpu.arch.hflags &= ~HF_GIF_MASK;
> +
> +	/* After a CLGI no interrupts should come */
> +	svm_clear_vintr(svm);
> +	svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
> +
> +	return 1;
> +}
> +
>  static int invalid_op_interception(struct vcpu_svm *svm,
>  				   struct kvm_run *kvm_run)
>  {
> @@ -1433,8 +1473,8 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm,
>  	[SVM_EXIT_VMMCALL]			= vmmcall_interception,
>  	[SVM_EXIT_VMLOAD]			= invalid_op_interception,
>  	[SVM_EXIT_VMSAVE]			= invalid_op_interception,
> -	[SVM_EXIT_STGI]				= invalid_op_interception,
> -	[SVM_EXIT_CLGI]				= invalid_op_interception,
> +	[SVM_EXIT_STGI]				= stgi_interception,
> +	[SVM_EXIT_CLGI]				= clgi_interception,
>  	[SVM_EXIT_SKINIT]			= invalid_op_interception,
>  	[SVM_EXIT_WBINVD]                       = emulate_on_interception,
>  	[SVM_EXIT_MONITOR]			= invalid_op_interception,
> @@ -1581,6 +1621,9 @@ static void svm_intr_assist(struct kvm_vcpu *vcpu)
>  	if (!kvm_cpu_has_interrupt(vcpu))
>  		goto out;
>  
> +	if (!(svm->vcpu.arch.hflags & HF_GIF_MASK))
> +		goto out;
> +
>  	if (!(vmcb->save.rflags & X86_EFLAGS_IF) ||
>  	    (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK) ||
>  	    (vmcb->control.event_inj & SVM_EVTINJ_VALID)) {
> @@ -1632,7 +1675,8 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
>  
>  	svm->vcpu.arch.interrupt_window_open =
>  		(!(control->int_state & SVM_INTERRUPT_SHADOW_MASK) &&
> -		 (svm->vmcb->save.rflags & X86_EFLAGS_IF));
> +		 (svm->vmcb->save.rflags & X86_EFLAGS_IF) &&
> +		 (svm->vcpu.arch.hflags & HF_GIF_MASK));
>  
>  	if (svm->vcpu.arch.interrupt_window_open && svm->vcpu.arch.irq_summary)
>  		/*
> diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
> index 982b6b2..3e25004 100644
> --- a/include/asm-x86/kvm_host.h
> +++ b/include/asm-x86/kvm_host.h
> @@ -245,6 +245,7 @@ struct kvm_vcpu_arch {
>  	unsigned long cr3;
>  	unsigned long cr4;
>  	unsigned long cr8;
> +	u32 hflags;
>  	u64 pdptrs[4]; /* pae */
>  	u64 shadow_efer;
>  	u64 apic_base;
> @@ -734,6 +735,8 @@ enum {
>  	TASK_SWITCH_GATE = 3,
>  };
>  
> +#define HF_GIF_MASK		(1 << 0)
> +
>  /*
>   * Hardware virtualization extension instructions may fault if a
>   * reboot turns off virtualization while processes are running.
> -- 
> 1.5.6