From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joel Schopp <joel.schopp@amd.com>
Subject: Re: [PATCH v3] x86: svm: use kvm_fast_pio_in()
Date: Tue, 3 Mar 2015 14:03:20 -0600
Message-ID: <54F61388.6090002@amd.com>
References: <20150302210202.2951.56810.stgit@joelvmguard2.amd.com>
 <20150303164431.GD25123@potion.brq.redhat.com>
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Cc: Gleb Natapov <gleb@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>, <kvm@vger.kernel.org>,
	David Kaplan <David.Kaplan@amd.com>,
	Joerg Roedel <joro@8bytes.org>, <linux-kernel@vger.kernel.org>,
	Borislav Petkov <bp@alien8.de>
To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>
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List-Id: kvm.vger.kernel.org


On 03/03/2015 10:44 AM, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote:
> 2015-03-02 15:02-0600, Joel Schopp:
>> +int kvm_fast_pio_in(struct kvm_vcpu *vcpu, int size, unsigned short=
 port)
>> +{
>> +	unsigned long val;
>> +	int ret =3D emulator_pio_in_emulated(&vcpu->arch.emulate_ctxt, siz=
e,
>> +					   port, &val, 1);
>> +
> Btw. does this return 1 in some scenario?
If a function returns a value it is always a good idea to check it and
act appropriately.  That said...
emulator_pio_in_emulated will return 1 if emulator_pio_in_out returns 1
or if vcpu->arch.pio.count !=3D 0
emulator_pio_in_out returns 1 if kernel_pio returns 0
kernel_pio returns 0 if kvm_io_bus_read returns 0