Re: [PATCH v7 09/12] PCI: liveupdate: Inherit ARI Forwarding Enable on preserved bridges

Pasha Tatashin <[email protected]> Fri, 17 Jul 2026 23:29:45 +0000

Newsgroups	org.infradead.lists.kexec,org.kernel.vger.linux-doc,org.kernel.vger.linux-kernel,org.kernel.vger.linux-pci,org.kvack.linux-mm
Message-ID	<178433098576.189683.2364970585754668266.b4-review@b4>

On Fri, 10 Jul 2026 21:26:12 +0000, David Matlack <[email protected]> wrote:
> diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
> index a95bfe5eff77..74a11e520f0d 100644
> --- a/drivers/pci/liveupdate.c
> +++ b/drivers/pci/liveupdate.c
> @@ -816,6 +820,20 @@ int pci_liveupdate_enable_acs(struct pci_dev *dev)
>  	return 0;
>  }
>  
> +int pci_liveupdate_configure_ari(struct pci_dev *dev)
> +{
> +	u16 val;
> +
> +	guard(rwsem_read)(&pci_liveupdate.rwsem);
> +
> +	if (!dev->liveupdate.incoming)
> +		return -EINVAL;
> +
> +	pcie_capability_read_word(dev, PCI_EXP_DEVCTL2, &val);
> +	dev->ari_enabled = !!(val & PCI_EXP_DEVCTL2_ARI);

unsigned int    ari_enabled:1;

Sashiko asks a valid question, what protects other bits in this word 
during modication?  At a very list a comment is needed.

-- 
Pasha Tatashin <[email protected]>