linux-kernel - Re: [patch 36/39] PCI/MSI: Validate MSIX contiguous restriction early

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Message-ID: <20221116163356.GA1116458@bhelgaas>
Date:   Wed, 16 Nov 2022 10:33:56 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ashok Raj <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
        Allen Hubbe <allenbh@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linuxppc-dev@...ts.ozlabs.org,
        "Ahmed S. Darwish" <darwi@...utronix.de>,
        Reinette Chatre <reinette.chatre@...el.com>
Subject: Re: [patch 36/39] PCI/MSI: Validate MSIX contiguous restriction early

On Fri, Nov 11, 2022 at 02:55:12PM +0100, Thomas Gleixner wrote:
> With interrupt domains the sanity check for MSI-X vector validation can be
> done _before_ any allocation happens. The sanity check only applies to the
> allocation functions which have an 'entries' array argument. The entries
> array is filled by the caller with the requested MSI-X indicies. Some drivers
> have gaps in the index space which is not supported on all architectures.
> 
> The PCI/MSI irqdomain has a 'feature' bit to enforce this validation late
> during the allocation phase.
> 
> Just do it right away before doing any other work along with the other
> sanity checks on that array.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

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

s/indicies/indices/ (commit log)
s/irqdomain/irq domain/?  IIRC previous logs used "irq domain"
s/MSIX/MSI-X/ (subject line)

> ---
>  drivers/pci/msi/msi.c |   11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -725,13 +725,17 @@ static int msix_capability_init(struct p
>  	return ret;
>  }
>  
> -static bool pci_msix_validate_entries(struct msix_entry *entries, int nvec, int hwsize)
> +static bool pci_msix_validate_entries(struct pci_dev *dev, struct msix_entry *entries,
> +				      int nvec, int hwsize)
>  {
> +	bool nogap;
>  	int i, j;
>  
>  	if (!entries)
>  		return true;
>  
> +	nogap = pci_msi_domain_supports(dev, MSI_FLAG_MSIX_CONTIGUOUS, DENY_LEGACY);
> +
>  	for (i = 0; i < nvec; i++) {
>  		/* Entry within hardware limit? */
>  		if (entries[i].entry >= hwsize)
> @@ -742,6 +746,9 @@ static bool pci_msix_validate_entries(st
>  			if (entries[i].entry == entries[j].entry)
>  				return false;
>  		}
> +		/* Check for unsupported gaps */
> +		if (nogap && entries[i].entry != i)
> +			return false;
>  	}
>  	return true;
>  }
> @@ -773,7 +780,7 @@ int __pci_enable_msix_range(struct pci_d
>  	if (hwsize < 0)
>  		return hwsize;
>  
> -	if (!pci_msix_validate_entries(entries, nvec, hwsize))
> +	if (!pci_msix_validate_entries(dev, entries, nvec, hwsize))
>  		return -EINVAL;
>  
>  	/* PCI_IRQ_VIRTUAL is a horrible hack! */
>