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Re: [PATCH v3 08/11] vpci/header: Emulate PCI_COMMAND register for guests


  • To: Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>
  • Date: Wed, 3 Nov 2021 10:36:36 +0000
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "julien@xxxxxxx" <julien@xxxxxxx>, "sstabellini@xxxxxxxxxx" <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <Oleksandr_Tyshchenko@xxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Artem Mygaiev <Artem_Mygaiev@xxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Rahul Singh <rahul.singh@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>
  • Delivery-date: Wed, 03 Nov 2021 10:36:49 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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  • Thread-topic: [PATCH v3 08/11] vpci/header: Emulate PCI_COMMAND register for guests


On 03.11.21 12:34, Jan Beulich wrote:
> On 03.11.2021 11:24, Oleksandr Andrushchenko wrote:
>> On 03.11.21 11:49, Jan Beulich wrote:
>>> Aiui you want to prevent the guest from clearing the bit if either
>>> MSI or MSI-X are in use. Symmetrically, when the guest enables MSI
>>> or MSI-X, you will want to force the bit set (which may well be in
>>> a separate, future patch).
>> static uint32_t emulate_cmd_reg(const struct pci_dev *pdev, uint32_t cmd)
>> {
>>       /* TODO: Add proper emulation for all bits of the command register. */
>>
>>       if ( (cmd & PCI_COMMAND_INTX_DISABLE) == 0 )
>>       {
>>           /* Guest wants to enable INTx. It can't be enabled if MSI/MSI-X 
>> enabled. */
>> #ifdef CONFIG_HAS_PCI_MSI
>>           if ( pdev->vpci->msi->enabled )
>>               cmd |= PCI_COMMAND_INTX_DISABLE;
>> #endif
>>       }
>>
>>       return cmd;
>> }
>>
>> Is this what you mean?
> Something along these lines, yes. I'd omit the outer if() for clarity /
> brevity.
Sure, thank you!
@Roger are you ok with this approach?
>
> Jan
>
>

 


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