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From: Sandor Bodo-Merle <sbodomerle@gmail.com>
To: "Pali Rohár" <pali@kernel.org>
Cc: linux-pci@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com
Subject: Re: pcie-iproc-msi.c: Bug in Multi-MSI support?
Date: Thu, 20 May 2021 15:47:46 +0200	[thread overview]
Message-ID: <CABLWAfQbKy=fpaY6J=gqtJy5L+pqNeqwU6qkVswYaWnVjiwAHw@mail.gmail.com> (raw)
In-Reply-To: <20210520120055.jl7vkqanv7wzeipq@pali>

Hi Pali,

thanks for catching this - i dig up the followup fixup commit we have
for the iproc multi MSI (it was sent to Broadcom - but unfortunately
we missed upstreaming it).

Commit fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
failed to reserve the proper number of bits from the inner domain.
We need to allocate the proper amount of bits otherwise the domains for
multiple PCIe endpoints may overlap and freeing one of them will result
in freeing unrelated MSI vectors.

Fixes: fc54bae28818 ("PCI: iproc: Allow allocation of multiple MSIs")
---
 drivers/pci/host/pcie-iproc-msi.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git drivers/pci/host/pcie-iproc-msi.c drivers/pci/host/pcie-iproc-msi.c
index 708fdb1065f8..a00492dccb74 100644
--- drivers/pci/host/pcie-iproc-msi.c
+++ drivers/pci/host/pcie-iproc-msi.c
@@ -260,11 +260,11 @@ static int iproc_msi_irq_domain_alloc(struct
irq_domain *domain,

        mutex_lock(&msi->bitmap_lock);

-       /* Allocate 'nr_cpus' number of MSI vectors each time */
+       /* Allocate 'nr_irqs' multiplied by 'nr_cpus' number of MSI
vectors each time */
        hwirq = bitmap_find_next_zero_area(msi->bitmap, msi->nr_msi_vecs, 0,
-                                          msi->nr_cpus, 0);
+                                          msi->nr_cpus * nr_irqs, 0);
        if (hwirq < msi->nr_msi_vecs) {
-               bitmap_set(msi->bitmap, hwirq, msi->nr_cpus);
+               bitmap_set(msi->bitmap, hwirq, msi->nr_cpus * nr_irqs);
        } else {
                mutex_unlock(&msi->bitmap_lock);
                return -ENOSPC;
@@ -292,7 +292,7 @@ static void iproc_msi_irq_domain_free(struct
irq_domain *domain,
        mutex_lock(&msi->bitmap_lock);

        hwirq = hwirq_to_canonical_hwirq(msi, data->hwirq);
-       bitmap_clear(msi->bitmap, hwirq, msi->nr_cpus);
+       bitmap_clear(msi->bitmap, hwirq, msi->nr_cpus * nr_irqs);

        mutex_unlock(&msi->bitmap_lock);


On Thu, May 20, 2021 at 2:04 PM Pali Rohár <pali@kernel.org> wrote:
>
> Hello!
>
> I think there is a bug in pcie-iproc-msi.c driver. It declares
> Multi MSI support via MSI_FLAG_MULTI_PCI_MSI flag, see:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pcie-iproc-msi.c?h=v5.12#n174
>
> but its iproc_msi_irq_domain_alloc() function completely ignores nr_irqs
> argument when allocating interrupt numbers from bitmap, see:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pcie-iproc-msi.c?h=v5.12#n246
>
> I think this this is incorrect as alloc callback should allocate nr_irqs
> multi interrupts as caller requested. All other drivers with Multi MSI
> support are doing it.
>
> Could you look at it?

  reply	other threads:[~2021-05-20 13:48 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20 12:00 pcie-iproc-msi.c: Bug in Multi-MSI support? Pali Rohár
2021-05-20 13:47 ` Sandor Bodo-Merle [this message]
2021-05-20 14:05   ` Pali Rohár
2021-05-20 14:22     ` Sandor Bodo-Merle
2021-05-20 17:11       ` Ray Jui
2021-05-20 19:31         ` Sandor Bodo-Merle
2021-05-21 11:39         ` Sandor Bodo-Merle
2021-05-21 14:00           ` Sandor Bodo-Merle
2021-05-24 10:37         ` Marc Zyngier
2021-05-25 17:27           ` Ray Jui
2021-05-25 17:35             ` Pali Rohár
2021-05-25 17:39               ` Ray Jui
2021-05-26  7:57             ` Marc Zyngier
2021-05-26 16:10               ` Sandor Bodo-Merle
2021-06-02  8:34                 ` Marc Zyngier
2021-06-03 16:59                   ` Ray Jui
2021-06-04  9:17                     ` Sandor Bodo-Merle
2021-06-04 16:47                       ` Ray Jui
2021-05-26 17:34               ` Ray Jui
2021-05-26 20:18                 ` Sandor Bodo-Merle

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