Re: [PATCH v4 3/5] powerpc/pseries/eeh: Add RTAS error validation helpers

[Sourabh Jain <sourabhjain@linux.ibm.com>]

On 31/08/26 12:24, Narayana Murty N wrote:
> Add pseries-specific infrastructure for RTAS-based EEH error injection.
>
> Define pr_fmt unconditionally at the top of eeh_pseries.c so all
> pr_*() calls carry the "EEH: " prefix:
>
>    #define pr_fmt(fmt) "EEH: " fmt

Could you please describe the overall goal of the helpers introduced by
this patch first, before discussing pr_fmt and the other macros?

>
> Define RTAS firmware error-type encodings as file-local constants.
> Only the two IOA bus-error types are supported; other PAPR encodings
> are not reachable through the generic EEH_ERR_TYPE_* UAPI:
>
>    RTAS_ERR_TYPE_IOA_BUS_ERROR     0x07
>    RTAS_ERR_TYPE_IOA_BUS_ERROR_64  0x0f
>
> Add RTAS_ERRINJCT_BUF_SIZE for the ibm,errinjct work buffer size.
>
> Add pseries_eeh_type_to_rtas() to translate the two generic EEH error
> types (EEH_ERR_TYPE_32, EEH_ERR_TYPE_64) into the corresponding RTAS
> ibm,errinjct encodings.
>
> Add validate_addr_mask_in_pe() to verify that a caller-provided address
> falls within a BAR of some device in the PE.  RTAS IOA bus-error
> injection requires a PCI/IOA bus address; validate_addr_mask_in_pe()
> accepts only PCI bus addresses.  VFIO userspace resource addresses are
> normalized to PCI bus addresses in vfio_iommu_spapr_tce.c before
> reaching this backend; no resource-address fallback is added here.
> Use pcibios_resource_to_bus() to convert each BAR resource to PCI bus
> address space before validating the address.  Returns -EINVAL (Linux
> errno) rather than a raw RTAS status.
>
> Add validate_errinjct_args() as a top-level validation wrapper that
> checks the PE pointer, maps the generic type, and validates the function
> range.  Address/mask validation against BARs is done in the buffer
> preparation step.
>
> Add prepare_errinjct_buffer() which:
>    - guards against NULL buf/pe/pe->phb
>    - zeroes the buffer unconditionally with memset()
>    - checks 32-bit truncation for the IOA_BUS_ERROR case
>    - calls validate_addr_mask_in_pe() for address validation
>    - supports only the IOA bus-error types (unreachable non-IOA
>      RTAS cases removed)
> The caller provides an exclusive per-call RTAS work-area buffer.
> Firmware session serialization is left to the caller.
>
> pseries_eeh_err_inject() retains the existing MMIO injection body
> unchanged in this patch.  It is replaced by the full RTAS session
> implementation in the next patch.  This keeps the patch bisectable:
> each commit builds and functions correctly independently.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202512101130.EYUo0oZx-lkp@intel.com/
> Signed-off-by: Narayana Murty N <nnmlinux@linux.ibm.com>
> ---
>   arch/powerpc/platforms/pseries/eeh_pseries.c | 215 +++++++++++++++++++
>   1 file changed, 215 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
> index b12ef382fec7..fafe0004e738 100644
> --- a/arch/powerpc/platforms/pseries/eeh_pseries.c
> +++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
> @@ -12,6 +12,8 @@
>    * Copyright Linas Vepstas 2005, 2006
>    */
>   
> +#define pr_fmt(fmt) "EEH: " fmt
> +
>   #include <linux/atomic.h>
>   #include <linux/delay.h>
>   #include <linux/export.h>
> @@ -786,6 +788,219 @@ static int pseries_notify_resume(struct eeh_dev *edev)
>   }
>   #endif
>   
> +/*
> + * RTAS firmware error-type encodings (PAPR).  These are pseries-private;
> + * user-space sees only the generic EEH_ERR_TYPE_* values from eeh.h.
> + * Only IOA bus-error types are supported; other PAPR encodings are not
> + * reachable through the generic EEH_ERR_TYPE_* UAPI.
> + */
> +#define RTAS_ERR_TYPE_IOA_BUS_ERROR		0x07
> +#define RTAS_ERR_TYPE_IOA_BUS_ERROR_64		0x0f
> +
> +/* Size of the ibm,errinjct work buffer as defined by PAPR */
> +#define RTAS_ERRINJCT_BUF_SIZE			SZ_1K
> +
> +/**
> + * pseries_eeh_type_to_rtas - Map generic EEH error type to RTAS encoding
> + * @type: generic EEH error type (EEH_ERR_TYPE_32, EEH_ERR_TYPE_64)
> + *
> + * Translates the generic VFIO/EEH error type passed from userspace into
> + * the RTAS-specific ibm,errinjct error type encoding defined by PAPR.
> + *
> + * Return: RTAS error type on success, -EINVAL for unknown types.
> + */
> +static int pseries_eeh_type_to_rtas(int type)
> +{
> +	switch (type) {
> +	case EEH_ERR_TYPE_32:
> +		return RTAS_ERR_TYPE_IOA_BUS_ERROR;
> +	case EEH_ERR_TYPE_64:
> +		return RTAS_ERR_TYPE_IOA_BUS_ERROR_64;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +/**
> + * validate_addr_mask_in_pe - Validate addr against PCI bus BAR addresses in PE
> + * @pe:   EEH PE containing one or more PCI devices
> + * @addr: PCI bus address to validate
> + * @mask: address mask (passed to firmware unchanged)
> + *
> + * RTAS IOA bus-error injection uses PCI bus addresses.  Linux PCI resources
> + * are CPU/resource addresses and may differ on pseries due to PHB window
> + * translation.  Convert each BAR resource to PCI bus address space before
> + * validating @addr.
> + *
> + * Zero addr and mask are accepted without BAR lookup (no-address injection).
> + *
> + * Return: 0 if valid, -EINVAL on invalid input.
> + */
> +static int validate_addr_mask_in_pe(struct eeh_pe *pe, unsigned long addr,
> +				    unsigned long mask)
> +{
> +	struct pci_bus_region region;
> +	struct eeh_dev *edev, *tmp;
> +	struct pci_dev *pdev;
> +	struct resource *res;
> +	resource_size_t bus_start;
> +	resource_size_t bus_len;
> +	int bar;
> +
> +	if (!addr && !mask)
> +		return 0;
> +
> +	if (!pe)
> +		return -EINVAL;
> +
> +	/*
> +	 * RTAS IOA bus-error injection uses PCI bus addresses. Linux PCI
> +	 * resources are CPU/resource addresses and may differ on pseries due
> +	 * to PHB window translation. Convert each BAR resource to PCI bus
> +	 * address space before validating @addr.
> +	 */
> +	eeh_pe_for_each_dev(pe, edev, tmp) {
> +		pdev = eeh_dev_to_pci_dev(edev);
> +		if (!pdev)
> +			continue;
> +
> +		for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> +			res = &pdev->resource[bar];
> +
> +			if (!resource_size(res))
> +				continue;
> +
> +			if (!(res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
> +				continue;
> +
> +			pcibios_resource_to_bus(pdev->bus, &region, res);
> +
> +			bus_start = region.start;
> +			bus_len = resource_size(res);
> +
> +			if ((resource_size_t)addr >= bus_start &&
> +			    ((resource_size_t)addr - bus_start) < bus_len) {
> +				pr_debug("addr=0x%lx mask=0x%lx validated in PCI bus BAR[%d] of %s: bus range 0x%llx-0x%llx\n",
> +					 addr, mask, bar, pci_name(pdev),
> +					 (unsigned long long)region.start,
> +					 (unsigned long long)region.end);
> +				return 0;
> +			}
> +		}
> +	}
> +
> +	pr_err("addr=0x%lx mask=0x%lx not within any PCI bus BAR of any device in PE\n",
> +	       addr, mask);
> +	return -EINVAL;
> +}
> +
> +/**
> + * validate_errinjct_args - Top-level validation for RTAS error injection arguments
> + * @pe:   EEH PE for the target device
> + * @type: generic EEH error type
> + * @func: error function selector
> + * @addr: address argument (type-dependent, may be zero)
> + * @mask: mask argument (type-dependent, may be zero)
> + *
> + * Validates all parameters before opening an RTAS injection session.
> + * Returns Linux errno values; does not return raw RTAS status codes.
> + *
> + * Return: 0 if all parameters are valid, negative errno otherwise.
> + */
> +static int validate_errinjct_args(struct eeh_pe *pe, int type, int func,
> +				  unsigned long addr, unsigned long mask)
> +{
> +	if (!pe || !pe->phb)
> +		return -EINVAL;
> +
> +	if (pseries_eeh_type_to_rtas(type) < 0)
> +		return -EINVAL;
> +
> +	if (func < EEH_ERR_FUNC_MIN || func > EEH_ERR_FUNC_MAX)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +/**
> + * prepare_errinjct_buffer() - Build ibm,errinjct work buffer
> + * @buf: RTAS error-injection work buffer
> + * @pe: EEH PE associated with the injection target
> + * @rtas_type: RTAS firmware error-injection type

rtas_type is confusing to me. How about err_type?

> + * @func: Error function selector
> + * @addr: Target PCI bus address
> + * @mask: Address mask passed to firmware
> + *
> + * Zeroes @buf and populates it according to the PAPR layout for the
> + * selected IOA bus-error injection type.
> + *
> + * The caller provides an exclusive per-call RTAS work-area buffer.
> + * Firmware session serialization is handled by pseries_eeh_err_inject().
> + *
> + * Return: 0 on success or a negative errno on invalid input.
> + */
> +static int prepare_errinjct_buffer(void *buf, struct eeh_pe *pe,
> +				   int rtas_type, int func,
> +				   unsigned long addr, unsigned long mask)
> +{
> +	__be64 *buf64 = (__be64 *)buf;
> +	__be32 *buf32 = (__be32 *)buf;
> +	int rc;
> +
> +	if (!buf || !pe || !pe->phb)
> +		return -EINVAL;
> +
> +	memset(buf, 0, RTAS_ERRINJCT_BUF_SIZE);
> +
> +	switch (rtas_type) {
> +	case RTAS_ERR_TYPE_IOA_BUS_ERROR:
> +		if (func < EEH_ERR_FUNC_MIN || func > EEH_ERR_FUNC_MAX)
> +			return -EINVAL;

This condition is common for both cases, so let take it out of switch.
And lets move the func check before memset.

> +
> +		if (upper_32_bits(addr) || upper_32_bits(mask)) {
> +			pr_err("32-bit IOA injection cannot encode addr=%#lx mask=%#lx\n",
> +			       addr, mask);
> +			return -EINVAL;
> +		}
> +
> +		rc = validate_addr_mask_in_pe(pe, addr, mask);
> +		if (rc)
> +			return rc;
> +
> +		buf32[0] = cpu_to_be32((u32)addr);
> +		buf32[1] = cpu_to_be32((u32)mask);
> +		buf32[2] = cpu_to_be32(pe->addr);
> +		buf32[3] = cpu_to_be32(BUID_HI(pe->phb->buid));
> +		buf32[4] = cpu_to_be32(BUID_LO(pe->phb->buid));
> +		buf32[5] = cpu_to_be32(func);
> +		break;
> +
> +	case RTAS_ERR_TYPE_IOA_BUS_ERROR_64:
> +		if (func < EEH_ERR_FUNC_MIN || func > EEH_ERR_FUNC_MAX)
> +			return -EINVAL;
> +
> +		rc = validate_addr_mask_in_pe(pe, addr, mask);
> +		if (rc)
> +			return rc;
> +
> +		buf64[0] = cpu_to_be64(addr);
> +		buf64[1] = cpu_to_be64(mask);
> +		buf32[4] = cpu_to_be32(pe->addr);
> +		buf32[5] = cpu_to_be32(BUID_HI(pe->phb->buid));
> +		buf32[6] = cpu_to_be32(BUID_LO(pe->phb->buid));
> +		buf32[7] = cpu_to_be32(func);
> +		break;
> +
> +	default:
> +		pr_err("unsupported RTAS error injection type 0x%x\n", rtas_type);
> +		return -EINVAL;
> +	}
> +
> +	pr_debug("errinjct buffer ready: rtas_type=0x%x func=%d addr=0x%lx mask=0x%lx\n",
> +		 rtas_type, func, addr, mask);
> +	return 0;
> +}
> +
>   /**
>    * pseries_eeh_err_inject - Inject specified error to the indicated PE
>    * @pe: the indicated PE