Commit 75b7c05e authored by Shivaprasad G Bhat's avatar Shivaprasad G Bhat Committed by Michael Ellerman
Browse files

powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall 

Add support for ND_REGION_ASYNC capability if the device tree
indicates 'ibm,hcall-flush-required' property in the NVDIMM node.
Flush is done by issuing H_SCM_FLUSH hcall to the hypervisor.

If the flush request failed, the hypervisor is expected to
to reflect the problem in the subsequent nvdimm H_SCM_HEALTH call.

This patch prevents mmap of namespaces with MAP_SYNC flag if the
nvdimm requires an explicit flush[1].

References:
[1] https://github.com/avocado-framework-tests/avocado-misc-tests/blob/master/memory/ndctl.py.data/map_sync.c



Signed-off-by: default avatarShivaprasad G Bhat <sbhat@linux.ibm.com>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
[mpe: Use unsigned long / long instead of uint64_t/int64_t]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/161703936121.36.7260632399582101498.stgit@e1fbed493c87
parent af072b1a

Documentation/powerpc/papr_hcalls.rst

+14 −0
Original line number Diff line number Diff line
@@ -275,6 +275,20 @@ Health Bitmap Flags: 
Given a DRC Index collect the performance statistics for NVDIMM and copy them

to the resultBuffer.



**H_SCM_FLUSH**



| Input: *drcIndex, continue-token*

| Out: *continue-token*

| Return Value: *H_SUCCESS, H_Parameter, H_P2, H_BUSY*



Given a DRC Index Flush the data to backend NVDIMM device.



The hcall returns H_BUSY when the flush takes longer time and the hcall needs

to be issued multiple times in order to be completely serviced. The

*continue-token* from the output to be passed in the argument list of

subsequent hcalls to the hypervisor until the hcall is completely serviced

at which point H_SUCCESS or other error is returned by the hypervisor.



References

==========

.. [1] "Power Architecture Platform Reference"

arch/powerpc/include/asm/hvcall.h

+2 −1
Original line number Diff line number Diff line
@@ -315,7 +315,8 @@ 
#define H_SCM_HEALTH            0x400

#define H_SCM_PERFORMANCE_STATS 0x418

#define H_RPT_INVALIDATE	0x448

#define MAX_HCALL_OPCODE	H_RPT_INVALIDATE

#define H_SCM_FLUSH		0x44C

#define MAX_HCALL_OPCODE	H_SCM_FLUSH



/* Scope args for H_SCM_UNBIND_ALL */

#define H_UNBIND_SCOPE_ALL (0x1)

arch/powerpc/platforms/pseries/papr_scm.c

+39 −0
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ struct papr_scm_priv { 
	uint64_t block_size;

	int metadata_size;

	bool is_volatile;

	bool hcall_flush_required;



	uint64_t bound_addr;
@@ -117,6 +118,38 @@ struct papr_scm_priv { 
	size_t stat_buffer_len;

};



static int papr_scm_pmem_flush(struct nd_region *nd_region,

			       struct bio *bio __maybe_unused)

{

	struct papr_scm_priv *p = nd_region_provider_data(nd_region);

	unsigned long ret_buf[PLPAR_HCALL_BUFSIZE], token = 0;

	long rc;



	dev_dbg(&p->pdev->dev, "flush drc 0x%x", p->drc_index);



	do {

		rc = plpar_hcall(H_SCM_FLUSH, ret_buf, p->drc_index, token);

		token = ret_buf[0];



		/* Check if we are stalled for some time */

		if (H_IS_LONG_BUSY(rc)) {

			msleep(get_longbusy_msecs(rc));

			rc = H_BUSY;

		} else if (rc == H_BUSY) {

			cond_resched();

		}

	} while (rc == H_BUSY);



	if (rc) {

		dev_err(&p->pdev->dev, "flush error: %lld", rc);

		rc = -EIO;

	} else {

		dev_dbg(&p->pdev->dev, "flush drc 0x%x complete", p->drc_index);

	}



	return rc;

}



static LIST_HEAD(papr_nd_regions);

static DEFINE_MUTEX(papr_ndr_lock);
@@ -943,6 +976,11 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p) 
	ndr_desc.num_mappings = 1;

	ndr_desc.nd_set = &p->nd_set;



	if (p->hcall_flush_required) {

		set_bit(ND_REGION_ASYNC, &ndr_desc.flags);

		ndr_desc.flush = papr_scm_pmem_flush;

	}



	if (p->is_volatile)

		p->region = nvdimm_volatile_region_create(p->bus, &ndr_desc);

	else {
@@ -1088,6 +1126,7 @@ static int papr_scm_probe(struct platform_device *pdev) 
	p->block_size = block_size;

	p->blocks = blocks;

	p->is_volatile = !of_property_read_bool(dn, "ibm,cache-flush-required");

	p->hcall_flush_required = of_property_read_bool(dn, "ibm,hcall-flush-required");



	/* We just need to ensure that set cookies are unique across */

	uuid_parse(uuid_str, (uuid_t *) uuid);