linux-kernel - Re: [PATCH v2] PCI: endpoint: Skip odd BAR when skipping 64bit BAR

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Date:   Fri, 24 May 2019 14:19:03 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Alan Mikhak <alan.mikhak@...ive.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <lorenzo.pieralisi@....com>,
        <linux-riscv@...ts.infradead.org>, <palmer@...ive.com>,
        <paul.walmsley@...ive.com>
Subject: Re: [PATCH v2] PCI: endpoint: Skip odd BAR when skipping 64bit BAR

Hi,

On 24/05/19 3:25 AM, Alan Mikhak wrote:
> Always skip odd bar when skipping 64bit BARs in pci_epf_test_set_bar()
> and pci_epf_test_alloc_space().
> 
> Otherwise, pci_epf_test_set_bar() will call pci_epc_set_bar() on odd loop
> index when skipping reserved 64bit BAR. Moreover, pci_epf_test_alloc_space()
> will call pci_epf_alloc_space() on bind for odd loop index when BAR is 64bit
> but leaks on subsequent unbind by not calling pci_epf_free_space().
> 
> Signed-off-by: Alan Mikhak <alan.mikhak@...ive.com>
> Reviewed-by: Paul Walmsley <paul.walmsley@...ive.com>
> ---
>  drivers/pci/endpoint/functions/pci-epf-test.c | 25 ++++++++++++-------------
>  1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 27806987e93b..96156a537922 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -389,7 +389,7 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
>  
>  static int pci_epf_test_set_bar(struct pci_epf *epf)
>  {
> -	int bar;
> +	int bar, add;
>  	int ret;
>  	struct pci_epf_bar *epf_bar;
>  	struct pci_epc *epc = epf->epc;
> @@ -400,8 +400,14 @@ static int pci_epf_test_set_bar(struct pci_epf *epf)
>  
>  	epc_features = epf_test->epc_features;
>  
> -	for (bar = BAR_0; bar <= BAR_5; bar++) {
> +	for (bar = BAR_0; bar <= BAR_5; bar += add) {
>  		epf_bar = &epf->bar[bar];
> +		/*
> +		 * pci_epc_set_bar() sets PCI_BASE_ADDRESS_MEM_TYPE_64
> +		 * if the specific implementation required a 64-bit BAR,
> +		 * even if we only requested a 32-bit BAR.
> +		 */

set_bar shouldn't set PCI_BASE_ADDRESS_MEM_TYPE_64. If a platform supports only
64-bit BAR, that should be specified in epc_features bar_fixed_64bit member.

Thanks
Kishon