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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Tue, 2 Apr 2019 18:23:32 +0200
Message-ID: <CAKv+Gu-tFpvKm4PSyxNkXHFSStfVCqOzdWCZjFTXiosZhoVKXg@mail.gmail.com>
Subject: Re: [PATCH v2] PCI: xilinx-nwl: Fix Multi MSI data programming
To:     Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        linux-pci <linux-pci@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
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On Mon, 11 Mar 2019 at 12:46, Bharat Kumar Gogada
<bharat.kumar.gogada@xilinx.com> wrote:
>
> The current Multi MSI data programming fails if multiple end points
> requesting MSI and multi MSI are connected with switch, i.e the current
> multi MSI data being given is not considering the number of vectors
> being requested in case of multi MSI.
> Due to this if multiple end points are connected and requesting MSI
> and multi MSI combination, the multi MSI data is ending up using
> wrong MSI data, which might be used by different device.
>
> Fix Multi MSI data programming with required alignment by
> using number of vectors being requested.
>
> Fixes: ab597d35ef11 ("PCI: xilinx-nwl: Add support for Xilinx NWL PCIe
> Host Controller")
> Signed-off-by: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>
> ---
> V2:
>  - Added more description of fix
> ---
>  drivers/pci/controller/pcie-xilinx-nwl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pcie-xilinx-nwl.c b/drivers/pci/controller/pcie-xilinx-nwl.c
> index 81538d7..36669c5 100644
> --- a/drivers/pci/controller/pcie-xilinx-nwl.c
> +++ b/drivers/pci/controller/pcie-xilinx-nwl.c
> @@ -484,7 +484,7 @@ static int nwl_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>
>         mutex_lock(&msi->lock);
>         bit = bitmap_find_next_zero_area(msi->bitmap, INT_PCI_MSI_NR, 0,
> -                                        nr_irqs, 0);
> +                                        nr_irqs, nr_irqs - 1);

Are you sure nr_irqs is guaranteed to be a power of 2?

>         if (bit >= INT_PCI_MSI_NR) {
>                 mutex_unlock(&msi->lock);
>                 return -ENOSPC;
> --
> 2.7.4
>
>
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