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Date:   Thu, 07 Oct 2021 15:42:06 +0100
Message-ID: <875yu8rj5t.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Rui Salvaterra <rsalvaterra@gmail.com>
Cc:     tglx@linutronix.de, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [REGRESSION][BISECTED] 5.15-rc1: Broken AHCI on NVIDIA ION (MCP79)
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On Thu, 07 Oct 2021 14:11:51 +0100,
Rui Salvaterra <rsalvaterra@gmail.com> wrote:
> 
> Hi again, Marc,
> 
> On Thu, 7 Oct 2021 at 13:15, Marc Zyngier <maz@kernel.org> wrote:
> >
> > 'Believe' is not a word I'd use. I know for a fact that all HW,
> > whether it is present, past or future is only a pile of hacks.
> >
> > Given that your report tends to indicate that we fail to enable the
> > interrupt for this device, this would be a possibility.
> 
> Heh. Guess what? The AHCI controller is lying throught its teeth. Your
> hack fixes boot for me. Everything seems to be working, even with such
> a big hammer.

Right. Let's see if we can be less brutal and only quirk the AHCI
device (patch below, completely untested). I'm a bit concerned that
all the devices in this system seem to report 'Maskable-'...

	M.

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 0099a00af361..2f9ec7210991 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -479,6 +479,9 @@ msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
 		goto out;
 
 	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
+	/* Lies, damned lies, and MSIs */
+	if (dev->dev_flags & PCI_DEV_FLAGS_HAS_MSI_MASKING)
+		control |= PCI_MSI_FLAGS_MASKBIT;
 
 	entry->msi_attrib.is_msix	= 0;
 	entry->msi_attrib.is_64		= !!(control & PCI_MSI_FLAGS_64BIT);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 4537d1ea14fd..dc7741431bf3 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5795,3 +5795,9 @@ static void apex_pci_fixup_class(struct pci_dev *pdev)
 }
 DECLARE_PCI_FIXUP_CLASS_HEADER(0x1ac1, 0x089a,
 			       PCI_CLASS_NOT_DEFINED, 8, apex_pci_fixup_class);
+
+static void nvidia_ion_ahci_fixup(struct pci_dev *pdev)
+{
+	pdev->dev_flags |= PCI_MSI_FLAGS_MASKBIT;
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NVIDIA, 0x0ab8, nvidia_ion_ahci_fixup);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index cd8aa6fce204..152a4d74f87f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -233,6 +233,8 @@ enum pci_dev_flags {
 	PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10),
 	/* Don't use Relaxed Ordering for TLPs directed at this device */
 	PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 11),
+	/* Device does honor MSI masking despite saying otherwise */
+	PCI_DEV_FLAGS_HAS_MSI_MASKING = (__force pci_dev_flags_t) (1 << 12),
 };
 
 enum pci_irq_reroute_variant {


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