[PATCH] PCI: apple: Initialize pcie->nvecs before using it

[PATCH] PCI: apple: Initialize pcie->nvecs before using it

[Sven Peter]

apple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of
MSIs available for each port. It is however called before apple_msi_init
which actually initializes pcie->nvecs.
Luckily, pcie->nvecs is part of kzalloc-ed structure and thus
initialized as zero. ilog2(0) happens to be 0xffffffff which then just
configures more MSIs in hardware than we actually have. This doesn't
break anything because we never hand out those vectors.
Let's swap the order of the two calls so that we use the correctly
initialized value.

Fixes: 476c41ed4597 ("PCI: apple: Implement MSI support")
Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
 drivers/pci/controller/pcie-apple.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index 66f37e403a09..8b7b084cf287 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -783,6 +783,10 @@ static int apple_pcie_init(struct pci_config_window *cfg)
 	cfg->priv = pcie;
 	INIT_LIST_HEAD(&pcie->ports);
 
+	ret = apple_msi_init(pcie);
+	if (ret)
+		return ret;
+
 	for_each_child_of_node(dev->of_node, of_port) {
 		ret = apple_pcie_setup_port(pcie, of_port);
 		if (ret) {
@@ -792,7 +796,7 @@ static int apple_pcie_init(struct pci_config_window *cfg)
 		}
 	}
 
-	return apple_msi_init(pcie);
+	return 0;
 }
 
 static int apple_pcie_probe(struct platform_device *pdev)
-- 
2.25.1

Re: [PATCH] PCI: apple: Initialize pcie->nvecs before using it

[Eric Curtin]

On Sat, 11 Mar 2023 at 13:41, Sven Peter <sven@svenpeter.dev> wrote:
>
> apple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of
> MSIs available for each port. It is however called before apple_msi_init
> which actually initializes pcie->nvecs.
> Luckily, pcie->nvecs is part of kzalloc-ed structure and thus
> initialized as zero. ilog2(0) happens to be 0xffffffff which then just
> configures more MSIs in hardware than we actually have. This doesn't
> break anything because we never hand out those vectors.
> Let's swap the order of the two calls so that we use the correctly
> initialized value.
>
> Fixes: 476c41ed4597 ("PCI: apple: Implement MSI support")
> Signed-off-by: Sven Peter <sven@svenpeter.dev>

Reviewed-by: Eric Curtin <ecurtin@redhat.com>

Is mise le meas/Regards,

Eric Curtin

> ---
>  drivers/pci/controller/pcie-apple.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index 66f37e403a09..8b7b084cf287 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -783,6 +783,10 @@ static int apple_pcie_init(struct pci_config_window *cfg)
>         cfg->priv = pcie;
>         INIT_LIST_HEAD(&pcie->ports);
>
> +       ret = apple_msi_init(pcie);
> +       if (ret)
> +               return ret;
> +
>         for_each_child_of_node(dev->of_node, of_port) {
>                 ret = apple_pcie_setup_port(pcie, of_port);
>                 if (ret) {
> @@ -792,7 +796,7 @@ static int apple_pcie_init(struct pci_config_window *cfg)
>                 }
>         }
>
> -       return apple_msi_init(pcie);
> +       return 0;
>  }
>
>  static int apple_pcie_probe(struct platform_device *pdev)
> --
> 2.25.1
>
>

Re: [PATCH] PCI: apple: Initialize pcie->nvecs before using it

[alyssa]

Whoops!

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

March 11, 2023 8:34 AM, "Sven Peter" <sven@svenpeter.dev> wrote:

> apple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of
> MSIs available for each port. It is however called before apple_msi_init
> which actually initializes pcie->nvecs.
> Luckily, pcie->nvecs is part of kzalloc-ed structure and thus
> initialized as zero. ilog2(0) happens to be 0xffffffff which then just
> configures more MSIs in hardware than we actually have. This doesn't
> break anything because we never hand out those vectors.
> Let's swap the order of the two calls so that we use the correctly
> initialized value.
> 
> Fixes: 476c41ed4597 ("PCI: apple: Implement MSI support")
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
> drivers/pci/controller/pcie-apple.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index 66f37e403a09..8b7b084cf287 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -783,6 +783,10 @@ static int apple_pcie_init(struct pci_config_window *cfg)
> cfg->priv = pcie;
> INIT_LIST_HEAD(&pcie->ports);
> 
> + ret = apple_msi_init(pcie);
> + if (ret)
> + return ret;
> +
> for_each_child_of_node(dev->of_node, of_port) {
> ret = apple_pcie_setup_port(pcie, of_port);
> if (ret) {
> @@ -792,7 +796,7 @@ static int apple_pcie_init(struct pci_config_window *cfg)
> }
> }
> 
> - return apple_msi_init(pcie);
> + return 0;
> }
> 
> static int apple_pcie_probe(struct platform_device *pdev)
> -- 
> 2.25.1

Re: [PATCH] PCI: apple: Initialize pcie->nvecs before using it

[Marc Zyngier]

On Sat, 11 Mar 2023 13:34:53 +0000,
Sven Peter <sven@svenpeter.dev> wrote:
> 
> apple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of
> MSIs available for each port. It is however called before apple_msi_init
> which actually initializes pcie->nvecs.
> Luckily, pcie->nvecs is part of kzalloc-ed structure and thus
> initialized as zero. ilog2(0) happens to be 0xffffffff which then just
> configures more MSIs in hardware than we actually have. This doesn't
> break anything because we never hand out those vectors.
> Let's swap the order of the two calls so that we use the correctly
> initialized value.
> 
> Fixes: 476c41ed4597 ("PCI: apple: Implement MSI support")
> Signed-off-by: Sven Peter <sven@svenpeter.dev>

Huh, how embarrassing... :-/

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH] PCI: apple: Initialize pcie->nvecs before using it

[Krzysztof Wilczyński]

Hello,

> apple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of
> MSIs available for each port. It is however called before apple_msi_init
> which actually initializes pcie->nvecs.
> Luckily, pcie->nvecs is part of kzalloc-ed structure and thus
> initialized as zero. ilog2(0) happens to be 0xffffffff which then just
> configures more MSIs in hardware than we actually have. This doesn't
> break anything because we never hand out those vectors.
> Let's swap the order of the two calls so that we use the correctly
> initialized value.

Applied to controller/apple, thank you!

[1/1] PCI: apple: Initialize pcie->nvecs before use
      https://git.kernel.org/pci/pci/c/328a16477027

	Krzysztof