Re: [PATCH] KVM: nVMX: Improve I/O exit handling

[Jan Kiszka <jan.kiszka@web.de>]

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On 2013-02-11 11:07, Nadav Har'El wrote:
> On Sun, Feb 10, 2013, Jan Kiszka wrote about "[PATCH] KVM: nVMX: Improve I/O exit handling":
>> +static bool nested_vmx_exit_handled_io(struct kvm_vcpu *vcpu,
>> +				       struct vmcs12 *vmcs12)
>> +{
>> +	unsigned long exit_qualification;
>> +	gpa_t bitmap, last_bitmap;
>> +	bool string, rep;
>> +	u16 port;
>> +	int size;
>> +	u8 b;
>> +
>> +	if (nested_cpu_has(get_vmcs12(vcpu), CPU_BASED_UNCOND_IO_EXITING))
>> +		return 1;
> 
> Instead of calling get_vmcs12(vcpu), you can just use "vmcs12" variable
> which you already have. I see I left the same redundant call also in
> nested_vmx_exit_handled_msr :(

Indeed, copy&pasted from there...

> 
>> +		if (port < 0x8000)
>> +			bitmap = vmcs12->io_bitmap_a;
>> +		else
>> +			bitmap = vmcs12->io_bitmap_b;
>> +		bitmap += port / 8;
> 
> In the port >= 0x8000, I believe need to subtract 0x8000 from the port
> number before using it as an offset into io_bitmap_b?

Oops. There was already a stupid bug in that path, failed to validate it
again. v2 will follow.

Thanks for reviewing,
Jan



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