Re: [PATCH] Print Guest VMCS state on vmexit failure

[Gleb Natapov <gleb@redhat.com>]

On Tue, Oct 20, 2009 at 09:50:45AM +0200, Chris Lalancette wrote:
> If we fail to handle a VMEXIT for some reason, print out a lot
> more debugging information about the state of the GUEST VMCS
> area.  This does not fix a bug, but helps a lot when trying to
> track down the cause of a VMEXIT/VMENTRY failure.
> 
> Signed-off-by: Chris Lalancette <clalance@redhat.com>
> ---
>  arch/x86/kvm/vmx.c |   38 ++++++++++++++++++++++++++++++++++++++
>  1 files changed, 38 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 311afd4..37b1682 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3452,6 +3452,14 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>  static const int kvm_vmx_max_exit_handlers =
>  	ARRAY_SIZE(kvm_vmx_exit_handlers);
>  
> +#define PRINT_GUEST_SEGMENT(seg) do {					\
> +	printk(KERN_DEBUG #seg ": SELECTOR 0x%lx, BASE 0x%lx, LIMIT 0x%lx, AR 0x%lx\n", \
> +	       vmcs_readl(GUEST_##seg##_SELECTOR),			\
> +	       vmcs_readl(GUEST_##seg##_BASE),				\
> +	       vmcs_readl(GUEST_##seg##_LIMIT),				\
> +	       vmcs_readl(GUEST_##seg##_AR_BYTES));			\
> +	while(0)
> +
>  /*
>   * The guest has exited.  See if we can fix it or if we need userspace
>   * assistance.
> @@ -3512,6 +3520,36 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
>  	else {
>  		vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
>  		vcpu->run->hw.hardware_exit_reason = exit_reason;
> +
> +		printk(KERN_DEBUG "GUEST STATE:\n");
> +		printk(KERN_DEBUG "CR0: 0x%lx\n", vmcs_readl(GUEST_CR0));
> +		printk(KERN_DEBUG "CR3: 0x%lx\n", vmcs_readl(GUEST_CR3));
> +		printk(KERN_DEBUG "CR4: 0x%lx\n", vmcs_readl(GUEST_CR4));
> +		printk(KERN_DEBUG "VMENTRY CONTROL: 0x%lx\n",
> +		       vmcs_readl(VM_ENTRY_CONTROLS));
> +		printk(KERN_DEBUG "DR7: 0x%lx\n", vmcs_readl(GUEST_DR7));
> +		printk(KERN_DEBUG "SYSENTER ESP: 0x%lx\n",
> +		       vmcs_readl(GUEST_SYSENTER_ESP));
> +		printk(KERN_DEBUG "SYSENTER EIP: 0x%lx\n",
> +		       vmcs_readl(GUEST_SYSENTER_EIP));
> +
> +		PRINT_GUEST_SEGMENT(CS);
> +		PRINT_GUEST_SEGMENT(SS);
> +		PRINT_GUEST_SEGMENT(DS);
> +		PRINT_GUEST_SEGMENT(ES);
> +		PRINT_GUEST_SEGMENT(FS);
> +		PRINT_GUEST_SEGMENT(GS);
> +		PRINT_GUEST_SEGMENT(TR);
> +		PRINT_GUEST_SEGMENT(LDTR);
> +
> +		printk(KERN_DEBUG "GDTR: BASE 0x%lx, LIMIT 0x%lx",
> +		       vmcs_readl(GUEST_GDTR_BASE),
> +		       vmcs_readl(GUEST_GDTR_LIMIT));
> +		printk(KERN_DEBUG "IDTR: BASE 0x%lx, LIMIT 0x%lx",
> +		       vmcs_readl(GUEST_IDTR_BASE),
> +		       vmcs_readl(GUEST_IDTR_LIMIT));
> +		printk(KERN_DEBUG "RIP: 0x%lx\n",vmcs_readl(GUEST_RIP));
> +		printk(KERN_DEBUG "RFLAGS: 0x%lx\n",vmcs_readl(GUEST_RFLAGS));
>  	}
>  	return 0;
Move this to separate function may be?  vmx_handle_exit() will be hard
to read with this blob in the middle.

--
			Gleb.