Re: [PATCH v7 4/6] PCI/IOV: Check that VF BAR fits within the reservation

[Ilpo Järvinen]

On Wed, 2 Apr 2025, Michał Winiarski wrote:

> When the resource representing VF MMIO BAR reservation is created, its
> size is always large enough to accommodate the BAR of all SR-IOV Virtual
> Functions that can potentially be created (total VFs). If for whatever
> reason it's not possible to accommodate all VFs - the resource is not
> assigned and no VFs can be created.
> 
> An upcoming change will allow VF BAR size to be modified by drivers at
> a later point in time, which means that the check for resource
> assignment is no longer sufficient.
> 
> Add an additional check that verifies that VF BAR for all enabled VFs
> fits within the underlying reservation resource.
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>
> ---
>  drivers/pci/iov.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index fee99e15a943f..2fafbd6a998f0 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -668,9 +668,12 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>  	nres = 0;
>  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
>  		int idx = pci_resource_num_from_vf_bar(i);
> +		resource_size_t vf_bar_sz = pci_iov_resource_size(dev, idx);
>  
>  		bars |= (1 << idx);
>  		res = &dev->resource[idx];
> +		if (vf_bar_sz * nr_virtfn > resource_size(res))
> +			continue;
>  		if (res->parent)
>  			nres++;
>  	}
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

-- 
 i.