Hi Shiva, Thanks for the patch. Few minor review comments: Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxx> writes: > 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 dimm health request call. s/dimm/nvdimm s/health request call/H_SCM_HEALTH hcall/ > > This patch prevents mmap of namespaces with MAP_SYNC flag if the > nvdimm requires explicit flush[1]. s/explicit/an explicit/ > > References: > [1] https://github.com/avocado-framework-tests/avocado-misc-tests/blob/master/memory/ndctl.py.data/map_sync.c > > Signed-off-by: Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxx> > --- > v1 - https://www.spinics.net/lists/kvm-ppc/msg18272.html > Changes from v1: > - Hcall semantics finalized, all changes are to accomodate them. > > Documentation/powerpc/papr_hcalls.rst | 14 ++++++++++ > arch/powerpc/include/asm/hvcall.h | 3 +- > arch/powerpc/platforms/pseries/papr_scm.c | 39 +++++++++++++++++++++++++++++ > 3 files changed, 55 insertions(+), 1 deletion(-) > > diff --git a/Documentation/powerpc/papr_hcalls.rst b/Documentation/powerpc/papr_hcalls.rst > index 48fcf1255a33..648f278eea8f 100644 > --- a/Documentation/powerpc/papr_hcalls.rst > +++ b/Documentation/powerpc/papr_hcalls.rst > @@ -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" > diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h > index ed6086d57b22..9f7729a97ebd 100644 > --- a/arch/powerpc/include/asm/hvcall.h > +++ b/arch/powerpc/include/asm/hvcall.h > @@ -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) > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c > index 835163f54244..f0407e135410 100644 > --- a/arch/powerpc/platforms/pseries/papr_scm.c > +++ b/arch/powerpc/platforms/pseries/papr_scm.c > @@ -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]; > + uint64_t token = 0; > + int64_t rc; > + Suggest adding a dev_dbg to to indicate a flush request to a drc. That way if the loop below gets stuck the issue can be debugged with kernel logs. > + 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); > > -- Cheers ~ Vaibhav
