linux-kernel - Re: [PATCH 1/1] PCI: dwc: Fix BAR0 wrong map to iATU6 after root complex reinit endpoint

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Message-ID: <ZYFrUWM7JXdv7rtb@x1-carbon>
Date: Tue, 19 Dec 2023 10:07:14 +0000
From: Niklas Cassel <Niklas.Cassel@....com>
To: Frank Li <Frank.Li@....com>
CC: "imx@...ts.linux.dev" <imx@...ts.linux.dev>, Jingoo Han
	<jingoohan1@...il.com>, Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
	Manivannan Sadhasivam <mani@...nel.org>, Lorenzo Pieralisi
	<lpieralisi@...nel.org>, Krzysztof Wilczyński
	<kw@...ux.com>, Rob Herring <robh@...nel.org>, Bjorn Helgaas
	<bhelgaas@...gle.com>, Jon Mason <jdmason@...zu.us>, "open list:PCI DRIVER
 FOR SYNOPSYS DESIGNWARE" <linux-pci@...r.kernel.org>, open list
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] PCI: dwc: Fix BAR0 wrong map to iATU6 after root
 complex reinit endpoint

On Mon, Dec 18, 2023 at 11:48:43PM -0500, Frank Li wrote:
> dw_pcie_ep_inbound_atu()
> {
> 	...
> 	if (!ep->bar_to_atu[bar])
> 		free_win = find_first_zero_bit(ep->ib_window_map, pci->num_ib_windows);
> 	else
> 		free_win = ep->bar_to_atu[bar];
> 	...
> }
> 
> The atu index 0 is valid case for atu number. The find_first_zero_bit()
> will return 6 when second time call into this function if atu is 0. Suppose
> it should use branch 'free_win = ep->bar_to_atu[bar]'.
> 
> Change 'bar_to_atu' to s8. Initialize bar_to_atu as -1 to indicate it have
> not allocate atu to the bar.
> 
> Reported-by: Niklas Cassel <Niklas.Cassel@....com>
> Close: https://lore.kernel.org/linux-pci/ZXt2A+Fusfz3luQV@x1-carbon/T/#u
> Fixes: 4284c88fff0e ("PCI: designware-ep: Allow pci_epc_set_bar() update inbound map address")
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> 
> Notes:
>     @Niklas:
>     	I have not test your case. I should be equal to previous's fix in
>     mail list.

Hello Frank,

Thank you for sending a proper fix for this!

Personally, I slightly prefer your fix that saves the iatu index + 1, and
keeps 0 to mean unused. That way, you don't need the memset, and you don't
need to change the type to signed, but either way is fine by me, so:

Reviewed-by: Niklas Cassel <niklas.cassel@....com>

> 
>  drivers/pci/controller/dwc/pcie-designware-ep.c | 11 ++++++++---
>  drivers/pci/controller/dwc/pcie-designware.h    |  2 +-
>  2 files changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index f6207989fc6ad..0ff5cd64f49b0 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -174,7 +174,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, u8 func_no, int type,
>  	u32 free_win;
>  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>  
> -	if (!ep->bar_to_atu[bar])
> +	if (ep->bar_to_atu[bar] < 0)
>  		free_win = find_first_zero_bit(ep->ib_window_map, pci->num_ib_windows);
>  	else
>  		free_win = ep->bar_to_atu[bar];
> @@ -228,14 +228,17 @@ static void dw_pcie_ep_clear_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
>  	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
>  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>  	enum pci_barno bar = epf_bar->barno;
> -	u32 atu_index = ep->bar_to_atu[bar];
> +	s8 atu_index = ep->bar_to_atu[bar];
> +
> +	if (atu_index < 0)
> +		return;
>  
>  	__dw_pcie_ep_reset_bar(pci, func_no, bar, epf_bar->flags);
>  
>  	dw_pcie_disable_atu(pci, PCIE_ATU_REGION_DIR_IB, atu_index);
>  	clear_bit(atu_index, ep->ib_window_map);
>  	ep->epf_bar[bar] = NULL;
> -	ep->bar_to_atu[bar] = 0;
> +	ep->bar_to_atu[bar] = -1;
>  }
>  
>  static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> @@ -767,6 +770,8 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>  		return -ENOMEM;
>  	ep->outbound_addr = addr;
>  
> +	memset(ep->bar_to_atu, -1, sizeof(ep->bar_to_atu));
> +
>  	epc = devm_pci_epc_create(dev, &epc_ops);
>  	if (IS_ERR(epc)) {
>  		dev_err(dev, "Failed to create epc device\n");
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 55ff76e3d3846..5879907c5cf25 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -362,7 +362,7 @@ struct dw_pcie_ep {
>  	phys_addr_t		phys_base;
>  	size_t			addr_size;
>  	size_t			page_size;
> -	u8			bar_to_atu[PCI_STD_NUM_BARS];
> +	s8			bar_to_atu[PCI_STD_NUM_BARS];
>  	phys_addr_t		*outbound_addr;
>  	unsigned long		*ib_window_map;
>  	unsigned long		*ob_window_map;
> -- 
> 2.34.1
>