NAK: [SRU][F][G][PATCH v2 1/1] s390/pci: Fix zpci_alloc_domain() over allocation

[Kleber Souza]

On 05.05.20 12:22, frank.heimes at canonical.com wrote:
> From: Niklas Schnelle <schnelle at linux.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1874057
> 
> Until now zpci_alloc_domain() only prevented more than
> CONFIG_PCI_NR_FUNCTIONS from being added when using automatic domain
> allocation. When explicit UIDs were defined UIDs above
> CONFIG_PCI_NR_FUNCTIONS were not counted at all.
> When more PCI functions are added this could lead to various errors
> including under sized IRQ vectors and similar issues.
> 
> Fix this by explicitly tracking the number of allocated domains.
> 
> Signed-off-by: Niklas Schnelle <schnelle at linux.ibm.com>
> OriginalAuthor: Niklas Schnelle <schnelle at linux.ibm.com>
> (backported from commit 969ae01bab2fe938b4c8324836038b5ac1c78fac)
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>

Hi Frank,

When we backport/cherry-pick patches from upstream or any other external
tree we need to keep the whole provenance block from the original commit
and add our tags below it. Looking at commit 969ae01bab2f, the original
provenance block is:

    Signed-off-by: Niklas Schnelle <schnelle at linux.ibm.com>
    Reviewed-by: Pierre Morel <pmorel at linux.ibm.com>
    Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>

All of this needs to be kept, adding the '(backported from ...)' and
your s-o-b lines below them. We don't need to add the 'OriginalAuthor:'
tag as git will automatically create the commit with the author set
to the name/email from the "From:" tag added as first line of the
patch.


Thanks,
Kleber


> ---
>  arch/s390/include/asm/pci.h |  1 +
>  arch/s390/pci/pci.c         | 34 ++++++++++++++++++++--------------
>  2 files changed, 21 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
> index 6087a4e9b2bf..7850e8c8c79a 100644
> --- a/arch/s390/include/asm/pci.h
> +++ b/arch/s390/include/asm/pci.h
> @@ -28,6 +28,7 @@ int pci_proc_domain(struct pci_bus *);
>  
>  #define ZPCI_NR_DMA_SPACES		1
>  #define ZPCI_NR_DEVICES			CONFIG_PCI_NR_FUNCTIONS
> +#define ZPCI_DOMAIN_BITMAP_SIZE		(1 << 16)
>  
>  /* PCI Function Controls */
>  #define ZPCI_FC_FN_ENABLED		0x80
> diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
> index 6105b1b6e49b..0af46683dd66 100644
> --- a/arch/s390/pci/pci.c
> +++ b/arch/s390/pci/pci.c
> @@ -39,8 +39,9 @@
>  static LIST_HEAD(zpci_list);
>  static DEFINE_SPINLOCK(zpci_list_lock);
>  
> -static DECLARE_BITMAP(zpci_domain, ZPCI_NR_DEVICES);
> +static DECLARE_BITMAP(zpci_domain, ZPCI_DOMAIN_BITMAP_SIZE);
>  static DEFINE_SPINLOCK(zpci_domain_lock);
> +static unsigned int zpci_num_domains_allocated;
>  
>  #define ZPCI_IOMAP_ENTRIES						\
>  	min(((unsigned long) ZPCI_NR_DEVICES * PCI_BAR_COUNT / 2),	\
> @@ -651,39 +652,44 @@ struct dev_pm_ops pcibios_pm_ops = {
>  
>  static int zpci_alloc_domain(struct zpci_dev *zdev)
>  {
> +	spin_lock(&zpci_domain_lock);
> +	if (zpci_num_domains_allocated > (ZPCI_NR_DEVICES - 1)) {
> +		spin_unlock(&zpci_domain_lock);
> +		pr_err("Adding PCI function %08x failed because the configured limit of %d is reached\n",
> +			zdev->fid, ZPCI_NR_DEVICES);
> +		return -ENOSPC;
> +	}
> +
>  	if (zpci_unique_uid) {
>  		zdev->domain = (u16) zdev->uid;
> -		if (zdev->domain >= ZPCI_NR_DEVICES)
> -			return 0;
> -
> -		spin_lock(&zpci_domain_lock);
>  		if (test_bit(zdev->domain, zpci_domain)) {
>  			spin_unlock(&zpci_domain_lock);
> +			pr_err("Adding PCI function %08x failed because domain %04x is already assigned\n",
> +				zdev->fid, zdev->domain);
>  			return -EEXIST;
>  		}
>  		set_bit(zdev->domain, zpci_domain);
> +		zpci_num_domains_allocated++;
>  		spin_unlock(&zpci_domain_lock);
>  		return 0;
>  	}
> -
> -	spin_lock(&zpci_domain_lock);
> +	/*
> +	 * We can always auto allocate domains below ZPCI_NR_DEVICES.
> +	 * There is either a free domain or we have reached the maximum in
> +	 * which case we would have bailed earlier.
> +	 */
>  	zdev->domain = find_first_zero_bit(zpci_domain, ZPCI_NR_DEVICES);
> -	if (zdev->domain == ZPCI_NR_DEVICES) {
> -		spin_unlock(&zpci_domain_lock);
> -		return -ENOSPC;
> -	}
>  	set_bit(zdev->domain, zpci_domain);
> +	zpci_num_domains_allocated++;
>  	spin_unlock(&zpci_domain_lock);
>  	return 0;
>  }
>  
>  static void zpci_free_domain(struct zpci_dev *zdev)
>  {
> -	if (zdev->domain >= ZPCI_NR_DEVICES)
> -		return;
> -
>  	spin_lock(&zpci_domain_lock);
>  	clear_bit(zdev->domain, zpci_domain);
> +	zpci_num_domains_allocated--;
>  	spin_unlock(&zpci_domain_lock);
>  }
>  
>