From: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx>
On Power-8 the AFU attr prefault_mode tried to improve storage fault
performance by prefaulting process segments. However Power-9 radix
mode doesn't have Storage-Segments and prefaulting Pages is too fine
grained.
So this patch updates prefault_mode_store() to not allow any other
value apart from CXL_PREFAULT_NONE when radix mode is enabled.
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: f24be42aab37 ("cxl: Add psl9 specific code")
Signed-off-by: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-class-cxl | 4 +++-
drivers/misc/cxl/sysfs.c | 16 ++++++++++++----
2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-class-cxl b/Documentation/ABI/testing/sysfs-class-cxl
index 640f65e79ef1..267920a1874b 100644
--- a/Documentation/ABI/testing/sysfs-class-cxl
+++ b/Documentation/ABI/testing/sysfs-class-cxl
@@ -69,7 +69,9 @@ Date: September 2014
Contact: linuxppc-dev@xxxxxxxxxxxxxxxx
Description: read/write
Set the mode for prefaulting in segments into the segment table
- when performing the START_WORK ioctl. Possible values:
+ when performing the START_WORK ioctl. Only applicable when
+ running under hashed page table mmu.
+ Possible values:
none: No prefaulting (default)
work_element_descriptor: Treat the work element
descriptor as an effective address and
diff --git a/drivers/misc/cxl/sysfs.c b/drivers/misc/cxl/sysfs.c
index 4b5a4c5d3c01..629e2e156412 100644
--- a/drivers/misc/cxl/sysfs.c
+++ b/drivers/misc/cxl/sysfs.c
@@ -353,12 +353,20 @@ static ssize_t prefault_mode_store(struct device *device,
struct cxl_afu *afu = to_cxl_afu(device);
enum prefault_modes mode = -1;
- if (!strncmp(buf, "work_element_descriptor", 23))
- mode = CXL_PREFAULT_WED;
- if (!strncmp(buf, "all", 3))
- mode = CXL_PREFAULT_ALL;
if (!strncmp(buf, "none", 4))
mode = CXL_PREFAULT_NONE;
+ else {
+ if (!radix_enabled()) {
+
+ /* only allowed when not in radix mode */
+ if (!strncmp(buf, "work_element_descriptor", 23))
+ mode = CXL_PREFAULT_WED;
+ if (!strncmp(buf, "all", 3))
+ mode = CXL_PREFAULT_ALL;
+ } else {
+ dev_err(device, "Cannot prefault with radix enabled\n");
+ }
+ }
if (mode == -1)
return -EINVAL;
--
2.17.0
