linux-kernel - Re: [patch V2 19/23] PCI/MSI: Sanitize MSIX table map handling

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Message-ID: <20211207210110.GA77246@bhelgaas>
Date:   Tue, 7 Dec 2021 15:01:10 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Megha Dey <megha.dey@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-pci@...r.kernel.org,
        Cedric Le Goater <clg@...d.org>,
        Juergen Gross <jgross@...e.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linuxppc-dev@...ts.ozlabs.org,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-mips@...r.kernel.org, Kalle Valo <kvalo@...eaurora.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        sparclinux@...r.kernel.org, x86@...nel.org,
        xen-devel@...ts.xenproject.org, ath11k@...ts.infradead.org,
        Wei Liu <wei.liu@...nel.org>, linux-hyperv@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>
Subject: Re: [patch V2 19/23] PCI/MSI: Sanitize MSIX table map handling

On Mon, Dec 06, 2021 at 11:27:54PM +0100, Thomas Gleixner wrote:
> Unmapping the MSIX base mapping in the loops which allocate/free MSI
> desciptors is daft and in the way of allowing runtime expansion of MSI-X
> descriptors.

s/MSIX/MSI-X/ (subject and first use in commit log)
s/desciptors/descriptors/

> Store the mapping in struct pci_dev and free it after freeing the MSI-X
> descriptors.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Tested-by: Juergen Gross <jgross@...e.com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

> ---
>  drivers/pci/msi/msi.c |   18 ++++++++----------
>  include/linux/pci.h   |    1 +
>  2 files changed, 9 insertions(+), 10 deletions(-)
> 
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -241,14 +241,14 @@ static void free_msi_irqs(struct pci_dev
>  	pci_msi_teardown_msi_irqs(dev);
>  
>  	list_for_each_entry_safe(entry, tmp, msi_list, list) {
> -		if (entry->pci.msi_attrib.is_msix) {
> -			if (list_is_last(&entry->list, msi_list))
> -				iounmap(entry->pci.mask_base);
> -		}
> -
>  		list_del(&entry->list);
>  		free_msi_entry(entry);
>  	}
> +
> +	if (dev->msix_base) {
> +		iounmap(dev->msix_base);
> +		dev->msix_base = NULL;
> +	}
>  }
>  
>  static void pci_intx_for_msi(struct pci_dev *dev, int enable)
> @@ -501,10 +501,6 @@ static int msix_setup_entries(struct pci
>  	for (i = 0, curmsk = masks; i < nvec; i++) {
>  		entry = alloc_msi_entry(&dev->dev, 1, curmsk);
>  		if (!entry) {
> -			if (!i)
> -				iounmap(base);
> -			else
> -				free_msi_irqs(dev);
>  			/* No enough memory. Don't try again */
>  			ret = -ENOMEM;
>  			goto out;
> @@ -602,12 +598,14 @@ static int msix_capability_init(struct p
>  		goto out_disable;
>  	}
>  
> +	dev->msix_base = base;
> +
>  	/* Ensure that all table entries are masked. */
>  	msix_mask_all(base, tsize);
>  
>  	ret = msix_setup_entries(dev, base, entries, nvec, affd);
>  	if (ret)
> -		goto out_disable;
> +		goto out_free;
>  
>  	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
>  	if (ret)
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -473,6 +473,7 @@ struct pci_dev {
>  	u8		ptm_granularity;
>  #endif
>  #ifdef CONFIG_PCI_MSI
> +	void __iomem	*msix_base;
>  	const struct attribute_group **msi_irq_groups;
>  #endif
>  	struct pci_vpd	vpd;
>