Hi Greg, Thanks for looking into this patch. Greg Kurz <groug@xxxxxxxx> writes: > On Thu, 1 Apr 2021 13:26:11 +1100 > David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote: > >> On Thu, Apr 01, 2021 at 06:35:19AM +0530, Vaibhav Jain wrote: >> > Add support for H_SCM_HEALTH hcall described at [1] for spapr >> > nvdimms. This enables guest to detect the 'unarmed' status of a >> > specific spapr nvdimm identified by its DRC and if its unarmed, mark >> > the region backed by the nvdimm as read-only. >> > >> > The patch adds h_scm_health() to handle the H_SCM_HEALTH hcall which >> > returns two 64-bit bitmaps (health bitmap, health bitmap mask) derived >> > from 'struct nvdimm->unarmed' member. >> > >> > Linux kernel side changes to enable handling of 'unarmed' nvdimms for >> > ppc64 are proposed at [2]. >> > >> > References: >> > [1] "Hypercall Op-codes (hcalls)" >> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/powerpc/papr_hcalls.rst#n220 >> > [2] "powerpc/papr_scm: Mark nvdimm as unarmed if needed during probe" >> > https://lore.kernel.org/linux-nvdimm/20210329113103.476760-1-vaibhav@xxxxxxxxxxxxx/ >> > >> > Signed-off-by: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx> >> >> As well as the handful of comments below, this will definitely need to >> wait for ppc-6.1 at this point. >> >> > --- >> > Changelog >> > >> > v2: >> > * Added a check for drc->dev to ensure that the dimm is plugged in >> > when servicing H_SCM_HEALTH. [ Shiva ] >> > * Instead of accessing the 'nvdimm->unarmed' member directly use the >> > object_property_get_bool accessor to fetch it. [ Shiva ] >> > * Update the usage of PAPR_PMEM_UNARMED* macros [ Greg ] >> > * Updated patch description reference#1 to point appropriate section >> > in the documentation. [ Greg ] >> > --- >> > hw/ppc/spapr_nvdimm.c | 38 ++++++++++++++++++++++++++++++++++++++ >> > include/hw/ppc/spapr.h | 3 ++- >> > 2 files changed, 40 insertions(+), 1 deletion(-) >> > >> > diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c >> > index b46c36917c..34096e4718 100644 >> > --- a/hw/ppc/spapr_nvdimm.c >> > +++ b/hw/ppc/spapr_nvdimm.c >> > @@ -31,6 +31,13 @@ >> > #include "qemu/range.h" >> > #include "hw/ppc/spapr_numa.h" >> > >> > +/* DIMM health bitmap bitmap indicators. Taken from kernel's papr_scm.c */ >> > +/* SCM device is unable to persist memory contents */ >> > +#define PAPR_PMEM_UNARMED (1ULL << (63 - 0)) >> >> You can use PPC_BIT() for more clarity here. >> > > I had already suggested PPC_BIT(0) but since this macro was copied > from the kernel source, I've let Vaibhav decide whether to use > PPC_BIT() or keep the macro and comment it comes from the kernel. > > I agree I prefer PPC_BIT(0) :-) > Have switched to PPC_BIT in v3 >> > +/* Bits status indicators for health bitmap indicating unarmed dimm */ >> > +#define PAPR_PMEM_UNARMED_MASK (PAPR_PMEM_UNARMED) >> >> I'm not sure why you want two equal #defines here. >> > > Especially, this define doesn't make sense for the hypervisor IMHO. > > It is _just_ the mask of bits for the "unarmed" state in the kernel. > Have gotten rid of this define in v3. We can revisit this In future when support for more bits is added. >> > + >> > bool spapr_nvdimm_validate(HotplugHandler *hotplug_dev, NVDIMMDevice *nvdimm, >> > uint64_t size, Error **errp) >> > { >> > @@ -467,6 +474,36 @@ static target_ulong h_scm_unbind_all(PowerPCCPU *cpu, SpaprMachineState *spapr, >> > return H_SUCCESS; >> > } >> > >> > +static target_ulong h_scm_health(PowerPCCPU *cpu, SpaprMachineState *spapr, >> > + target_ulong opcode, target_ulong *args) >> > +{ >> > + uint32_t drc_index = args[0]; >> > + SpaprDrc *drc = spapr_drc_by_index(drc_index); >> > + NVDIMMDevice *nvdimm; >> > + >> > + if (drc && spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PMEM) { >> >> This will fail badly if !drc (given index is way out of bounds). I'm >> pretty sure you want >> if (!drc || spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PMEM) { >> >> >> > + return H_PARAMETER; >> > + } >> > + >> > + /* Ensure that the dimm is plugged in */ >> > + if (!drc->dev) { >> > + return H_HARDWARE; >> >> H_HARDWARE doesn't seem right - it's the guest that has chosen to >> attempt this on an unplugged LMB, not the (virtual) hardware's fault. >> > > Yes. As already suggested, simply do the same as in other hcall > implementations in this file, e.g. from h_scm_bind_mem() : > > if (!drc || !drc->dev || > spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PMEM) { > return H_PARAMETER; > } > Yes, have used the same construct in the fixed v3 >> > + } >> > + >> > + nvdimm = NVDIMM(drc->dev); >> > + >> > + args[0] = 0; >> > + /* Check if the nvdimm is unarmed and send its status via health bitmaps */ > > Not sure this comment is super useful. > Have reworked this function in v3. >> > + if (object_property_get_bool(OBJECT(nvdimm), NVDIMM_UNARMED_PROP, NULL)) { >> > + args[0] |= PAPR_PMEM_UNARMED; >> > + } >> > + >> > + /* Update the health bitmap with the applicable mask */ >> > + args[1] = PAPR_PMEM_UNARMED_MASK; > > I still think this is a misuse of PAPR_PMEM_UNARMED_MASK... The > meaning of args[1] is "health-bit-valid-bitmap indicate which > bits in health-bitmap are valid" according to the documentation. > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/powerpc/papr_hcalls.rst#n228 > > Without any further detail, I tend to consider this as a hint > to the guest on the bits supported by the hypervisor. Since > we can only set PAPR_PMEM_UNARMED, for now, args[1] should > be set to just that bit PAPR_PMEM_UNARMED. Other bits can > be added later if QEMU supports more of them. > Agree and addressed in v3. >> > + >> > + return H_SUCCESS; >> > +} >> > + >> > static void spapr_scm_register_types(void) >> > { >> > /* qemu/scm specific hcalls */ >> > @@ -475,6 +512,7 @@ static void spapr_scm_register_types(void) >> > spapr_register_hypercall(H_SCM_BIND_MEM, h_scm_bind_mem); >> > spapr_register_hypercall(H_SCM_UNBIND_MEM, h_scm_unbind_mem); >> > spapr_register_hypercall(H_SCM_UNBIND_ALL, h_scm_unbind_all); >> > + spapr_register_hypercall(H_SCM_HEALTH, h_scm_health); >> > } >> > >> > type_init(spapr_scm_register_types) >> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h >> > index 47cebaf3ac..6e1eafb05d 100644 >> > --- a/include/hw/ppc/spapr.h >> > +++ b/include/hw/ppc/spapr.h >> > @@ -538,8 +538,9 @@ struct SpaprMachineState { >> > #define H_SCM_BIND_MEM 0x3EC >> > #define H_SCM_UNBIND_MEM 0x3F0 >> > #define H_SCM_UNBIND_ALL 0x3FC >> > +#define H_SCM_HEALTH 0x400 >> > >> > -#define MAX_HCALL_OPCODE H_SCM_UNBIND_ALL >> > +#define MAX_HCALL_OPCODE H_SCM_HEALTH >> > >> > /* The hcalls above are standardized in PAPR and implemented by pHyp >> > * as well. >> > -- Cheers ~ Vaibhav
