[PATCH 1/2] powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL

[Vaibhav Jain]

The new hcall named H_SCM_UNBIND_ALL has been introduce that can
unbind all the memory drc memory-blocks assigned to an lpar. This is
more efficient than using H_SCM_UNBIND_MEM as currently we don't
support partial unbind of drc memory-blocks.

Hence this patch proposes following changes to drc_pmem_unbind():

    * Update drc_pmem_unbind() to replace hcall H_SCM_UNBIND_MEM to
      H_SCM_UNBIND_ALL.

    * Update drc_pmem_unbind() to handles cases when PHYP asks the guest
      kernel to wait for specific amount of time before retrying the
      hcall via the 'LONG_BUSY' return value. In case it takes more
      than 1 second to unbind the memory log a warning.

    * Ensure appropriate error code is returned back from the function
      in case of an error.

Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h         |  2 +-
 arch/powerpc/platforms/pseries/papr_scm.c | 37 ++++++++++++++++++++---
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/hvcall.h 
b/arch/powerpc/include/asm/hvcall.h
index 463c63a9fcf1..bb56fa0f976c 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -302,7 +302,7 @@
 #define H_SCM_UNBIND_MEM        0x3F0
 #define H_SCM_QUERY_BLOCK_MEM_BINDING 0x3F4
 #define H_SCM_QUERY_LOGICAL_MEM_BINDING 0x3F8
-#define H_SCM_MEM_QUERY                0x3FC
+#define H_SCM_UNBIND_ALL        0x3FC
 #define H_SCM_BLOCK_CLEAR       0x400
 #define MAX_HCALL_OPCODE       H_SCM_BLOCK_CLEAR
 
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c 
b/arch/powerpc/platforms/pseries/papr_scm.c
index 96c53b23e58f..d790e4e4ffb3 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -11,11 +11,16 @@
 #include <linux/sched.h>
 #include <linux/libnvdimm.h>
 #include <linux/platform_device.h>
+#include <linux/delay.h>
 
 #include <asm/plpar_wrappers.h>
 
 #define BIND_ANY_ADDR (~0ul)
 
+/* Scope args for H_SCM_UNBIND_ALL */
+#define H_UNBIND_SCOPE_ALL (0x1)
+#define H_UNBIND_SCOPE_DRC (0x2)
+
 #define PAPR_SCM_DIMM_CMD_MASK \
        ((1ul << ND_CMD_GET_CONFIG_SIZE) | \
         (1ul << ND_CMD_GET_CONFIG_DATA) | \
@@ -78,21 +83,43 @@ static int drc_pmem_unbind(struct papr_scm_priv *p)
 {
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
        uint64_t rc, token;
+       unsigned long starttime;
 
        token = 0;
 
-       /* NB: unbind has the same retry requirements mentioned above */
+       dev_dbg(&p->pdev->dev, "unbind drc %x\n", p->drc_index);
+
+       /* NB: unbind_all has the same retry requirements as drc_pmem_bind() */
+       starttime = HZ;
        do {
-               rc = plpar_hcall(H_SCM_UNBIND_MEM, ret, p->drc_index,
-                               p->bound_addr, p->blocks, token);
+               /* If this is taking too much time then log warning */
+               if (jiffies_to_msecs(HZ - starttime) > 1000) {
+                       dev_warn(&p->pdev->dev,
+                                "unbind taking > 1s to complete\n");
+                       starttime = HZ;
+               }
+
+               /* Unbind of all SCM resources associated with drcIndex */
+               rc = plpar_hcall(H_SCM_UNBIND_ALL, ret, H_UNBIND_SCOPE_DRC,
+                                p->drc_index, token);
                token = ret[0];
-               cond_resched();
+
+               /* Check if we are stalled for some time */
+               if (H_IS_LONG_BUSY(rc)) {
+                       msleep(get_longbusy_msecs(rc));
+                       rc = H_BUSY;
+                       token = 0;
+
+               } else if (rc == H_BUSY) {
+                       cond_resched();
+               }
+
        } while (rc == H_BUSY);
 
        if (rc)
                dev_err(&p->pdev->dev, "unbind error: %lld\n", rc);
 
-       return !!rc;
+       return rc == H_SUCCESS ? 0 : -ENXIO;
 }
 
 static int papr_scm_meta_get(struct papr_scm_priv *p,
-- 
2.21.0