[PATCH v6 2/5] powerpc/pseries/eeh: Add RTAS error injection helpers

[Narayana Murty N <nnmlinux@linux.ibm.com>]

Prepare the pSeries EEH backend for RTAS error injection by adding
helpers that:

  * map generic EEH error types to RTAS/PAPR error types;
  * validate IOA addresses against the target PE.

Define pr_fmt unconditionally at the top of eeh_pseries.c so all
pr_*() calls carry the "EEH: " prefix.

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.  Only standard BARs
(BAR0..BAR5) are searched; ROM and bridge resources are not IOA
bus-error targets.  Hold pci_rescan_remove_lock while traversing PE
devices and their BAR resources so PCI device removal cannot race the
address validation.

Skip unassigned or disabled BARs explicitly: on pseries,
pcibios_fixup_resources() zero-bases unassigned BARs (start=0,
end=size-1) and sets IORESOURCE_UNSET, so resource_size() is non-zero
for them and pcibios_resource_to_bus() treats them as bus address zero.
Use pci_resource_len() (which returns 0 when end==0) instead of
resource_size(), and reject BARs with IORESOURCE_UNSET or
IORESOURCE_DISABLED set.

Returns -EINVAL (Linux errno) rather than a raw RTAS status.

validate_errinjct_args() and prepare_errinjct_buffer() are introduced
in the next patch alongside their callers so each intermediate commit
builds cleanly with CONFIG_WERROR.

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 | 134 +++++++++++++++++++
 1 file changed, 134 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index b12ef382fec7..28b1fd19e8bc 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>
@@ -23,6 +25,7 @@
 #include <linux/rbtree.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
+#include <linux/sizes.h>
 #include <linux/spinlock.h>
 #include <linux/crash_dump.h>
 
@@ -786,6 +789,137 @@ 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;
+	bool found = false;
+	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.
+	 *
+	 * Hold pci_rescan_remove_lock across the traversal to protect pdev
+	 * lifetime: pci_stop_and_remove_bus_device() requires this lock.
+	 */
+	pci_lock_rescan_remove();
+	eeh_pe_for_each_dev(pe, edev, tmp) {
+		pdev = eeh_dev_to_pci_dev(edev);
+		if (!pdev)
+			continue;
+
+		/*
+		 * Validate against standard BARs (BAR0..BAR5) only.
+		 * ROM and bridge resources are not IOA bus-error targets.
+		 */
+		for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
+			res = &pdev->resource[bar];
+
+			/*
+			 * Skip unassigned or disabled BARs.  On pseries,
+			 * pcibios_fixup_resources() zero-bases unassigned BARs
+			 * (start=0, end=size-1) and sets IORESOURCE_UNSET.
+			 * resource_size() is non-zero for such BARs, and
+			 * pcibios_resource_to_bus() treats them as bus address
+			 * zero, so they must be excluded explicitly.
+			 * Use pci_resource_len() which returns 0 when end==0.
+			 */
+			if (!pci_resource_len(pdev, bar))
+				continue;
+
+			if (!(res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
+				continue;
+
+			if (res->flags & (IORESOURCE_UNSET | IORESOURCE_DISABLED))
+				continue;
+
+			pcibios_resource_to_bus(pdev->bus, &region, res);
+
+			bus_start = region.start;
+			bus_len = pci_resource_len(pdev, bar);
+
+			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);
+				found = true;
+				goto done;
+			}
+		}
+	}
+done:
+	pci_unlock_rescan_remove();
+
+	if (!found)
+		pr_err("addr=0x%lx mask=0x%lx not within any PCI bus BAR of any device in PE\n",
+		       addr, mask);
+	return found ? 0 : -EINVAL;
+}
+
 /**
  * pseries_eeh_err_inject - Inject specified error to the indicated PE
  * @pe: the indicated PE
-- 
2.54.0