Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <a5f51ed8-b7b0-8f28-0e17-8f16ccb9abe1@linux.intel.com>
Date:   Mon, 3 Apr 2023 14:00:12 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.9.0
Subject: Re: [PATCH v4] PCI: vmd: Add the module param to adjust MSI mode
Content-Language: en-US
To:     Xinghui Li <korantwork@gmail.com>
Cc:     Bjorn Helgaas <helgaas@kernel.org>, kbusch@kernel.org,
        jonathan.derrick@linux.dev, lpieralisi@kernel.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xinghui Li <korantli@tencent.com>
References: <20230329163107.GA3061927@bhelgaas>
 <0603c75d-82d3-01d5-ffe7-b648c1f02f0e@linux.intel.com>
 <CAEm4hYXwGuuZiKb9psXPyau+zKq-w=VboJEuYbS0FbY-iT-EmA@mail.gmail.com>
From:   "Patel, Nirmal" <nirmal.patel@linux.intel.com>
In-Reply-To: <CAEm4hYXwGuuZiKb9psXPyau+zKq-w=VboJEuYbS0FbY-iT-EmA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 4/2/2023 7:34 AM, Xinghui Li wrote:
> On Thu, Mar 30, 2023 at 2:49 PM Patel, Nirmal
> <nirmal.patel@linux.intel.com> wrote:
>> How about adding a boolean flag by comparing user input for module
>> parameter msi_remap? and add the flag at
>>
>>     - if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) || msi_flag
>>         || offset[0] || offset[1])
>>
>> Correct if I am wrong, but in this way we can cover all the cases.
>> If user adds msi_remap=on, msi_flag=true and enables remapping.
>> If user adds msi_remap=off, msi_flag=false and disables remapping.
>> If user doesn't add anything, msi_flag=false and decision will be
>> made same as current implementation. This will cover guest OS case
>> as well.
>>
> Sorry, I don't quite get your point. How is msi_flag assigned?
> Do you mean when msi_remap=no, the msi_flag is assigned as true?
> And msi_remap=off, the msi_flag is assigned as false?
>
> Thanks~

if msi_remap=on, then msi_flag=true;
if msi_remap=off, then msi_flag=false.