Commit b1713975 authored by David Hildenbrand's avatar David Hildenbrand Committed by Michael Ellerman
Browse files

powerpc/pseries/cmm: Simulation mode 



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

Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191031142933.10779-11-david@redhat.com
parent e8decafe

arch/powerpc/platforms/pseries/cmm.c

+30 −8
Original line number Diff line number Diff line
@@ -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;



	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);

		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:
@@ -590,7 +612,7 @@ 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();

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