[PATCH v1 10/12] powerpc/pseries: CMM: Simulation mode

David Hildenbrand
2019-10-31T14:30:53Z

Let's allow to test the implementation without needing HW support. When
"simulate=1" is specified when loading the module, we bypass all HW
checks and HW calls. The sysfs file "simulate_loan_target_kb" can be
used to simulate HW requests.

The simualtion mode can be activated using
modprobe cmm debug=1 simulate=1
And the requested loan target can be changed using
echo X > /sys/devices/system/cmm/cmm0/simulate_loan_target_kb

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Richard Fontana <rfontana@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arun KS <arunks@codeaurora.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/powerpc/platforms/pseries/cmm.c | 38 ++++++++++++++++++++++------
1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
index a6ec2bbb1f91..63bb576b05da 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -51,6 +51,8 @@ static unsigned int oom_kb = CMM_OOM_KB;
static unsigned int cmm_debug = CMM_DEBUG;
static unsigned int cmm_disabled = CMM_DISABLE;
static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
+static bool __read_mostly simulate;
+static unsigned long simulate_loan_target_kb;
static struct device cmm_dev;

MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
@@ -74,6 +76,8 @@ MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
module_param_named(debug, cmm_debug, uint, 0644);
MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
"[Default=" __stringify(CMM_DEBUG) "]");
+module_param_named(simulate, simulate, bool, 0444);
+MODULE_PARM_DESC(simulate, "Enable simulation mode (no communication with hw).");

#define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }

@@ -94,6 +98,9 @@ static long plpar_page_set_loaned(struct page *page)
long rc = 0;
int i;

+ if (unlikely(simulate))
+ return 0;
+
for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0);

@@ -111,6 +118,9 @@ static long plpar_page_set_active(struct page *page)
long rc = 0;
int i;

+ if (unlikely(simulate))
+ return 0;
+
for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0);

@@ -234,13 +244,17 @@ static void cmm_get_mpp(void)
signed long active_pages_target, page_loan_request, target;
signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;

- rc = h_get_mpp(&mpp_data);
-
- if (rc != H_SUCCESS)
- return;
-
- page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
- target = page_loan_request + __loaned_pages;
+ if (likely(!simulate)) {
+ rc = h_get_mpp(&mpp_data);
+ if (rc != H_SUCCESS)
+ return;
+ page_loan_request = div_s64((s64)mpp_data.loan_request,
+ PAGE_SIZE);
+ target = page_loan_request + __loaned_pages;
+ } else {
+ target = KB2PAGES(simulate_loan_target_kb);
+ page_loan_request = target - __loaned_pages;
+ }

if (target < 0 || total_pages < min_mem_pages)
target = 0;
@@ -362,6 +376,9 @@ static struct device_attribute *cmm_attrs[] = {
&dev_attr_oom_freed_kb,
};

+static DEVICE_ULONG_ATTR(simulate_loan_target_kb, 0644,
+ simulate_loan_target_kb);
+
static struct bus_type cmm_subsys = {
.name = "cmm",
.dev_name = "cmm",
@@ -396,6 +413,11 @@ static int cmm_sysfs_register(struct device *dev)
goto fail;
}

+ if (!simulate)
+ return 0;
+ rc = device_create_file(dev, &dev_attr_simulate_loan_target_kb.attr);
+ if (rc)
+ goto fail;
return 0;

fail:
@@ -589,7 +611,7 @@ static int cmm_init(void)
{
int rc;

- if (!firmware_has_feature(FW_FEATURE_CMO))
+ if (!firmware_has_feature(FW_FEATURE_CMO) && !simulate)
return -EOPNOTSUPP;

rc = cmm_balloon_compaction_init();
--
2.21.0