Re: [PATCH v7 24/27] cxl/pci: Disable root port interrupts in RCH mode

Dave Jiang
2023-06-23T22:09:05Z

On 6/22/23 13:55, Terry Bowman wrote:
> The RCH root port contains root command AER registers that should not be
> enabled.[1] Disable these to prevent root port interrupts.
>
> [1] CXL 3.0 - 12.2.1.1 RCH Downstream Port-detected Errors
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
> drivers/cxl/core/core.h | 6 ++++++
> drivers/cxl/core/pci.c | 29 +++++++++++++++++++++++++++++
> drivers/cxl/core/port.c | 3 +++
> 3 files changed, 38 insertions(+)
>
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 87467c633123..880bac9db376 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -86,4 +86,10 @@ enum cxl_poison_trace_type {
> CXL_POISON_TRACE_CLEAR,
> };
>
> +#ifdef CONFIG_PCIEAER_CXL
> +void cxl_disable_rch_root_ints(struct cxl_dport *dport);
> +#else
> +static inline void cxl_disable_rch_root_ints(struct cxl_dport *dport) { };
> +#endif
> +
> #endif /* __CXL_CORE_H__ */
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 9e0eba5ccfc4..897830c19d1a 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -838,6 +838,35 @@ static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
> cxl_handle_rdport_ras(cxlds, dport);
> }
>
> +void cxl_disable_rch_root_ints(struct cxl_dport *dport)
> +{
> + void __iomem *aer_base = dport->regs.dport_aer;
> + struct pci_host_bridge *bridge;
> + u32 aer_cmd_mask, aer_cmd;
> +
> + if (!aer_base)
> + return;
> +
> + bridge = to_pci_host_bridge(dport->dport_dev);
> +
> + /*
> + * Disable RCH root port command interrupts.
> + * CXL 3.0 12.2.1.1 - RCH Downstream Port-detected Errors
> + *
> + * This sequence may not be necessary. CXL spec states disabling
> + * the root cmd register's interrupts is required. But, PCI spec
> + * shows these are disabled by default on reset.
> + */
> + if (bridge->native_cxl_error) {
> + aer_cmd_mask = (PCI_ERR_ROOT_CMD_COR_EN |
> + PCI_ERR_ROOT_CMD_NONFATAL_EN |
> + PCI_ERR_ROOT_CMD_FATAL_EN);
> + aer_cmd = readl(aer_base + PCI_ERR_ROOT_COMMAND);
> + aer_cmd &= ~aer_cmd_mask;
> + writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
> + }
> +}
> +
> #else
> static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds) { }
> #endif
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index a92794e6b7b4..2fdfb31f16c1 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -1037,6 +1037,9 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
>
> cxl_dport_map_regs(dport);
>
> + if (dport->rch)
> + cxl_disable_rch_root_ints(dport);
> +
> cond_cxl_root_lock(port);
> rc = add_dport(port, dport);
> cond_cxl_root_unlock(port);