Replace the legacy MMIO stub in pseries_eeh_err_inject() with a full
PAPR-compliant RTAS error injection path using the existing RTAS
work-area allocator.

The mutex is not a buffer lock; it serializes the firmware session
open/inject/close sequence as required by PAPR.  No global buffer
is allocated or used.

VFIO EEH error injection exposes a generic userspace ABI.  pSeries maps
the generic EEH error types to RTAS ibm,errinjct encodings via
pseries_eeh_type_to_rtas().  EEH_ERR_TYPE_32 and EEH_ERR_TYPE_64 are
unchanged; their values are defined in arch/powerpc/include/uapi/asm/eeh.h
and are not renumbered.

Tested with corresponding QEMU patches:
https://lore.kernel.org/all/[email protected]/

Signed-off-by: Narayana Murty N <[email protected]>
---
 arch/powerpc/platforms/pseries/eeh_pseries.c | 123 ++++++++++++++-----
 1 file changed, 95 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c 
b/arch/powerpc/platforms/pseries/eeh_pseries.c
index fafe0004e738..fcb8c560d813 100644
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -25,6 +25,7 @@
 #include <linux/rbtree.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
+#include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/crash_dump.h>
 
@@ -34,6 +35,7 @@
 #include <asm/machdep.h>
 #include <asm/ppc-pci.h>
 #include <asm/rtas.h>
+#include <asm/rtas-work-area.h>
 
 /* RTAS tokens */
 static int ibm_set_eeh_option;
@@ -958,8 +960,6 @@ static int prepare_errinjct_buffer(void *buf, struct eeh_pe 
*pe,
                        return -EINVAL;
 
                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;
                }
 
@@ -992,50 +992,117 @@ static int prepare_errinjct_buffer(void *buf, struct 
eeh_pe *pe,
                break;
 
        default:
-               pr_err("unsupported RTAS error injection type 0x%x\n", 
rtas_type);
+               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-local mutex serializes the open/inject/close RTAS session */
+static DEFINE_MUTEX(pseries_errinjct_mutex);
+
 /**
  * pseries_eeh_err_inject - Inject specified error to the indicated PE
  * @pe: the indicated PE
- * @type: error type
- * @func: specific error type
- * @addr: address
- * @mask: address mask
- * The routine is called to inject specified error, which is
- * determined by @type and @func, to the indicated PE
+ * @type: generic EEH error type (EEH_ERR_TYPE_32 or EEH_ERR_TYPE_64)
+ * @func: specific error function
+ * @addr: address argument (type-dependent, may be zero)
+ * @mask: address mask (type-dependent, may be zero)
+ *
+ * Implements PAPR-compliant error injection using:
+ *   ibm,open-errinjct -> ibm,errinjct -> ibm,close-errinjct
+ *
+ * A short-lived RTAS work area is allocated per call; no global buffer
+ * is used.  pseries_errinjct_mutex serializes the open/inject/close
+ * session sequence.
+ *
+ * Return: 0 on success, negative errno on failure.
  */
 static int pseries_eeh_err_inject(struct eeh_pe *pe, int type, int func,
                                  unsigned long addr, unsigned long mask)
 {
-       struct  eeh_dev *pdev;
+       struct rtas_work_area *area;
+       phys_addr_t area_phys;
+       u32 buf_phys;
+       void *buf;
+       int open_token, errinjct_token, close_token;
+       int session_token;
+       int rtas_type;
+       int close_rc;
+       int rc;
+
+       rc = validate_errinjct_args(pe, type, func, addr, mask);
+       if (rc)
+               return rc;
 
-       /* Check on PCI error type */
-       if (type != EEH_ERR_TYPE_32 && type != EEH_ERR_TYPE_64)
+       rtas_type = pseries_eeh_type_to_rtas(type);
+       if (rtas_type < 0)
                return -EINVAL;
 
-       switch (func) {
-       case EEH_ERR_FUNC_LD_MEM_ADDR:
-       case EEH_ERR_FUNC_LD_MEM_DATA:
-       case EEH_ERR_FUNC_ST_MEM_ADDR:
-       case EEH_ERR_FUNC_ST_MEM_DATA:
-               /* injects a MMIO error for all pdev's belonging to PE */
-               pci_lock_rescan_remove();
-               list_for_each_entry(pdev, &pe->edevs, entry)
-                       eeh_pe_inject_mmio_error(pdev->pdev);
-               pci_unlock_rescan_remove();
-               break;
-       default:
-               return -ERANGE;
+       open_token    = rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT);
+       errinjct_token = rtas_function_token(RTAS_FN_IBM_ERRINJCT);
+       close_token   = rtas_function_token(RTAS_FN_IBM_CLOSE_ERRINJCT);
+
+       if (open_token    == RTAS_UNKNOWN_SERVICE ||
+           errinjct_token == RTAS_UNKNOWN_SERVICE ||
+           close_token   == RTAS_UNKNOWN_SERVICE)
+               return -ENODEV;
+
+       area = rtas_work_area_alloc(RTAS_ERRINJCT_BUF_SIZE);
+       buf  = rtas_work_area_raw_buf(area);
+       area_phys = rtas_work_area_phys(area);
+
+       if (WARN_ON_ONCE(upper_32_bits(area_phys))) {
+               rc = -ERANGE;
+               goto out_free_area;
        }
 
-       return 0;
+       buf_phys = lower_32_bits(area_phys);
+
+       rc = prepare_errinjct_buffer(buf, pe, rtas_type, func, addr, mask);
+       if (rc)
+               goto out_free_area;
+
+       mutex_lock(&pseries_errinjct_mutex);
+
+       do {
+               rc = rtas_call(open_token, 0, 2, &session_token);
+       } while (rtas_busy_delay(rc));
+
+       if (rc) {
+               pr_err("ibm,open-errinjct failed: status=%d\n", rc);
+               rc = rtas_error_rc(rc);
+               goto out_unlock;
+       }
+
+       do {
+               rc = rtas_call(errinjct_token, 3, 1, NULL,
+                              rtas_type, session_token, buf_phys);
+       } while (rtas_busy_delay(rc));
+
+       if (rc) {
+               pr_err("ibm,errinjct failed: status=%d\n", rc);
+               rc = rtas_error_rc(rc);
+       }
+
+       do {
+               close_rc = rtas_call(close_token, 1, 1, NULL, session_token);
+       } while (rtas_busy_delay(close_rc));
+
+       if (close_rc) {
+               pr_warn("ibm,close-errinjct failed: status=%d\n", close_rc);
+               if (!rc)
+                       rc = rtas_error_rc(close_rc);
+       }
+
+out_unlock:
+       mutex_unlock(&pseries_errinjct_mutex);
+
+out_free_area:
+       rtas_work_area_free(area);
+       return rc;
 }
 
 static struct eeh_ops pseries_eeh_ops = {
-- 
2.51.1


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