Re: [PATCH 2/3] PCI: endpoint: Add size check for fixed size BARs in pci_epc_set_bar()

[Frank Li <Frank.li@nxp.com>]

On Thu, Nov 14, 2024 at 12:03:28PM +0100, Niklas Cassel wrote:
> A BAR of type BAR_FIXED has a fixed BAR size (the size cannot be changed).
>
> When using pci_epf_alloc_space() to allocate backing memory for a BAR,
> pci_epf_alloc_space() will always set the size to the fixed BAR size if
> the BAR type is BAR_FIXED (and will give an error if you the requested size
> is larger than the fixed BAR size).
>
> However, some drivers might not call pci_epf_alloc_space() before calling
> pci_epc_set_bar(), so add a check in pci_epc_set_bar() to ensure that an
> EPF driver cannot set a size different from the fixed BAR size, if the BAR
> type is BAR_FIXED.
>
> The pci_epc_function_is_valid() check is removed because this check is now
> done by pci_epc_get_features().
>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> ---
>  drivers/pci/endpoint/pci-epc-core.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index bed7c7d1fe3c3..c69c133701c92 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -609,10 +609,17 @@ EXPORT_SYMBOL_GPL(pci_epc_clear_bar);
>  int pci_epc_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
>  		    struct pci_epf_bar *epf_bar)
>  {
> -	int ret;
> +	const struct pci_epc_features *epc_features;
> +	enum pci_barno bar = epf_bar->barno;
>  	int flags = epf_bar->flags;
> +	int ret;
>
> -	if (!pci_epc_function_is_valid(epc, func_no, vfunc_no))
> +	epc_features = pci_epc_get_features(epc, func_no, vfunc_no);
> +	if (!epc_features)
> +		return -EINVAL;
> +
> +	if (epc_features->bar[bar].type == BAR_FIXED &&
> +	    (epc_features->bar[bar].fixed_size != epf_bar->size))
>  		return -EINVAL;
>
>  	if ((epf_bar->barno == BAR_5 && flags & PCI_BASE_ADDRESS_MEM_TYPE_64) ||
> --
> 2.47.0
>