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Message-ID: <87czu2q25h.wl-maz@kernel.org>
Date: Fri, 07 May 2021 11:16:58 +0100
From: Marc Zyngier <maz@...nel.org>
To: Pali Rohár <pali@...nel.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
Rob Herring <robh@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Russell King <rmk+kernel@...linux.org.uk>,
Marek Behún <kabel@...nel.org>,
Remi Pommarel <repk@...plefau.lt>, Xogium <contact@...ium.me>,
Tomasz Maciej Nowak <tmn505@...il.com>,
linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 17/42] PCI: aardvark: Fix support for MSI interrupts
On Thu, 06 May 2021 16:31:28 +0100,
Pali Rohár <pali@...nel.org> wrote:
>
> MSI domain callback .alloc (implemented by advk_msi_irq_domain_alloc()
> function) should return zero on success. Returning non-zero value indicates
> failure. Fix return value of this function as in many cases it now returns
> failure while allocating IRQs.
>
> Aardvark hardware supports Multi-MSI and MSI_FLAG_MULTI_PCI_MSI is already
> set. But when allocating MSI interrupt numbers for Multi-MSI, they need to
> be properly aligned, otherwise endpoint devices send MSI interrupt with
> incorrect numbers. Fix this issue by using function bitmap_find_free_region()
> instead of bitmap_find_next_zero_area().
>
> To ensure that aligned MSI interrupt numbers are used by endpoint devices,
> we cannot use Linux virtual irq numbers (as they are random and not
> properly aligned). So use hwirq numbers allocated by the function
> bitmap_find_free_region(), which are aligned. This needs an update in
> advk_msi_irq_compose_msi_msg() and advk_pcie_handle_msi() functions to do
> proper mapping between Linux virtual irq numbers and hwirq MSI inner domain
> numbers.
>
> Also the whole 16-bit MSI number is stored in the PCIE_MSI_PAYLOAD_REG
> register, not only lower 8 bits. Fix reading content of this register.
>
> This change fixes receiving MSI interrupts on Armada 3720 boards and allows
> using NVMe disks which use Multi-MSI feature with 3 interrupts.
>
> Without this change, NVMe disks just freeze booting Linux on Armada 3720
> boards as linux nvme-core.c driver is waiting 60s for an interrupt.
>
> Signed-off-by: Pali Rohár <pali@...nel.org>
> Reviewed-by: Marek Behún <kabel@...nel.org>
> Cc: stable@...r.kernel.org # f21a8b1b6837 ("PCI: aardvark: Move to MSI handling using generic MSI support")
> ---
> drivers/pci/controller/pci-aardvark.c | 32 ++++++++++++++++-----------
> 1 file changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 366d7480bc1b..498810c00b6d 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -118,6 +118,7 @@
> #define PCIE_MSI_STATUS_REG (CONTROL_BASE_ADDR + 0x58)
> #define PCIE_MSI_MASK_REG (CONTROL_BASE_ADDR + 0x5C)
> #define PCIE_MSI_PAYLOAD_REG (CONTROL_BASE_ADDR + 0x9C)
> +#define PCIE_MSI_DATA_MASK GENMASK(15, 0)
See my comment below about this addition.
> /* LMI registers base address and register offsets */
> #define LMI_BASE_ADDR 0x6000
> @@ -861,7 +862,7 @@ static void advk_msi_irq_compose_msi_msg(struct irq_data *data,
>
> msg->address_lo = lower_32_bits(msi_msg);
> msg->address_hi = upper_32_bits(msi_msg);
> - msg->data = data->irq;
> + msg->data = data->hwirq;
> }
>
> static int advk_msi_set_affinity(struct irq_data *irq_data,
> @@ -878,15 +879,11 @@ static int advk_msi_irq_domain_alloc(struct irq_domain *domain,
> int hwirq, i;
>
> mutex_lock(&pcie->msi_used_lock);
> - hwirq = bitmap_find_next_zero_area(pcie->msi_used, MSI_IRQ_NUM,
> - 0, nr_irqs, 0);
> - if (hwirq >= MSI_IRQ_NUM) {
> - mutex_unlock(&pcie->msi_used_lock);
> - return -ENOSPC;
> - }
> -
> - bitmap_set(pcie->msi_used, hwirq, nr_irqs);
> + hwirq = bitmap_find_free_region(pcie->msi_used, MSI_IRQ_NUM,
> + order_base_2(nr_irqs));
> mutex_unlock(&pcie->msi_used_lock);
> + if (hwirq < 0)
> + return -ENOSPC;
>
> for (i = 0; i < nr_irqs; i++)
> irq_domain_set_info(domain, virq + i, hwirq + i,
> @@ -894,7 +891,7 @@ static int advk_msi_irq_domain_alloc(struct irq_domain *domain,
> domain->host_data, handle_simple_irq,
> NULL, NULL);
>
> - return hwirq;
> + return 0;
> }
>
> static void advk_msi_irq_domain_free(struct irq_domain *domain,
> @@ -904,7 +901,7 @@ static void advk_msi_irq_domain_free(struct irq_domain *domain,
> struct advk_pcie *pcie = domain->host_data;
>
> mutex_lock(&pcie->msi_used_lock);
> - bitmap_clear(pcie->msi_used, d->hwirq, nr_irqs);
> + bitmap_release_region(pcie->msi_used, d->hwirq, order_base_2(nr_irqs));
> mutex_unlock(&pcie->msi_used_lock);
> }
>
> @@ -1048,6 +1045,7 @@ static void advk_pcie_handle_msi(struct advk_pcie *pcie)
> {
> u32 msi_val, msi_mask, msi_status, msi_idx;
> u16 msi_data;
> + int virq;
>
> msi_mask = advk_readl(pcie, PCIE_MSI_MASK_REG);
> msi_val = advk_readl(pcie, PCIE_MSI_STATUS_REG);
> @@ -1057,9 +1055,17 @@ static void advk_pcie_handle_msi(struct advk_pcie *pcie)
> if (!(BIT(msi_idx) & msi_status))
> continue;
>
> + /*
> + * msi_idx contains bits [4:0] of the msi_data and msi_data
> + * contains 16bit MSI interrupt number from MSI inner domain
> + */
> advk_writel(pcie, BIT(msi_idx), PCIE_MSI_STATUS_REG);
> - msi_data = advk_readl(pcie, PCIE_MSI_PAYLOAD_REG) & 0xFF;
> - generic_handle_irq(msi_data);
> + msi_data = advk_readl(pcie, PCIE_MSI_PAYLOAD_REG) & PCIE_MSI_DATA_MASK;
Can this be moved to a separate patch? It seems like this patch should
only focus on correctly dealing with the irq/hwirq issues.
> + virq = irq_find_mapping(pcie->msi_inner_domain, msi_data);
> + if (virq)
> + generic_handle_irq(virq);
> + else
> + dev_err(&pcie->pdev->dev, "unexpected MSI 0x%04hx\n", msi_data);
Same concern about the unmitigated screaming.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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