On Tue, Mar 23, 2021 at 09:47:55AM -0400, Shivaprasad G Bhat wrote:
> The patch adds the 'sync-dax' property to the nvdimm device.
>
> When the sync-dax is 'off', the device tree property
> "hcall-flush-required" is added to the nvdimm node which makes the
> guest to issue H_SCM_FLUSH hcalls to request for flushes explicitly.
> This would be the default behaviour without sync-dax property set
> for the nvdimm device.
>
> The sync-dax="on" would mean the guest need not make flush requests
> to the qemu. On previous machine versions the sync-dax is set to be
> "on" by default using the hw_compat magic.
>
> Signed-off-by: Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxx>
> ---
> hw/core/machine.c | 1 +
> hw/mem/nvdimm.c | 1 +
> hw/ppc/spapr_nvdimm.c | 17 +++++++++++++++++
> include/hw/mem/nvdimm.h | 10 ++++++++++
> include/hw/ppc/spapr.h | 1 +
> 5 files changed, 30 insertions(+)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 257a664ea2..f843643574 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -41,6 +41,7 @@ GlobalProperty hw_compat_5_2[] = {
> { "PIIX4_PM", "smm-compat", "on"},
> { "virtio-blk-device", "report-discard-granularity", "off" },
> { "virtio-net-pci", "vectors", "3"},
> + { "nvdimm", "sync-dax", "on" },
> };
> const size_t hw_compat_5_2_len = G_N_ELEMENTS(hw_compat_5_2);
>
> diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
> index 7397b67156..8f0e29b191 100644
> --- a/hw/mem/nvdimm.c
> +++ b/hw/mem/nvdimm.c
> @@ -229,6 +229,7 @@ static void nvdimm_write_label_data(NVDIMMDevice *nvdimm, const void *buf,
>
> static Property nvdimm_properties[] = {
> DEFINE_PROP_BOOL(NVDIMM_UNARMED_PROP, NVDIMMDevice, unarmed, false),
> + DEFINE_PROP_BOOL(NVDIMM_SYNC_DAX_PROP, NVDIMMDevice, sync_dax, false),
I'm a bit uncomfortable adding this base NVDIMM property without at
least some logic about how it's handled on non-PAPR platforms.
> DEFINE_PROP_END_OF_LIST(),
> };
>
> diff --git a/hw/ppc/spapr_nvdimm.c b/hw/ppc/spapr_nvdimm.c
> index 883317c1ed..dd1c90251b 100644
> --- a/hw/ppc/spapr_nvdimm.c
> +++ b/hw/ppc/spapr_nvdimm.c
> @@ -125,6 +125,9 @@ static int spapr_dt_nvdimm(SpaprMachineState *spapr, void *fdt,
> uint64_t lsize = nvdimm->label_size;
> uint64_t size = object_property_get_int(OBJECT(nvdimm), PC_DIMM_SIZE_PROP,
> NULL);
> + bool sync_dax = object_property_get_bool(OBJECT(nvdimm),
> + NVDIMM_SYNC_DAX_PROP,
> + &error_abort);
>
> drc = spapr_drc_by_id(TYPE_SPAPR_DRC_PMEM, slot);
> g_assert(drc);
> @@ -159,6 +162,11 @@ static int spapr_dt_nvdimm(SpaprMachineState *spapr, void *fdt,
> "operating-system")));
> _FDT(fdt_setprop(fdt, child_offset, "ibm,cache-flush-required", NULL, 0));
>
> + if (!sync_dax) {
> + _FDT(fdt_setprop(fdt, child_offset, "ibm,hcall-flush-required",
> + NULL, 0));
> + }
> +
> return child_offset;
> }
>
> @@ -567,10 +575,12 @@ static target_ulong h_scm_flush(PowerPCCPU *cpu, SpaprMachineState *spapr,
> target_ulong opcode, target_ulong *args)
> {
> int ret;
> + bool sync_dax;
> uint32_t drc_index = args[0];
> uint64_t continue_token = args[1];
> SpaprDrc *drc = spapr_drc_by_index(drc_index);
> PCDIMMDevice *dimm;
> + NVDIMMDevice *nvdimm;
> HostMemoryBackend *backend = NULL;
> SpaprNVDIMMDeviceFlushState *state;
> ThreadPool *pool = aio_get_thread_pool(qemu_get_aio_context());
> @@ -580,6 +590,13 @@ static target_ulong h_scm_flush(PowerPCCPU *cpu, SpaprMachineState *spapr,
> return H_PARAMETER;
> }
>
> + nvdimm = NVDIMM(drc->dev);
> + sync_dax = object_property_get_bool(OBJECT(nvdimm), NVDIMM_SYNC_DAX_PROP,
> + &error_abort);
> + if (sync_dax) {
> + return H_UNSUPPORTED;
Do you want to return UNSUPPORTED here, or just H_SUCCESS, since the
flush should be a no-op in this case.
> + }
> +
> if (continue_token != 0) {
> ret = spapr_nvdimm_get_flush_status(continue_token);
> if (H_IS_LONG_BUSY(ret)) {
> diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h
> index bcf62f825c..f82979cf2f 100644
> --- a/include/hw/mem/nvdimm.h
> +++ b/include/hw/mem/nvdimm.h
> @@ -51,6 +51,7 @@ OBJECT_DECLARE_TYPE(NVDIMMDevice, NVDIMMClass, NVDIMM)
> #define NVDIMM_LABEL_SIZE_PROP "label-size"
> #define NVDIMM_UUID_PROP "uuid"
> #define NVDIMM_UNARMED_PROP "unarmed"
> +#define NVDIMM_SYNC_DAX_PROP "sync-dax"
>
> struct NVDIMMDevice {
> /* private */
> @@ -85,6 +86,15 @@ struct NVDIMMDevice {
> */
> bool unarmed;
>
> + /*
> + * On PPC64,
> + * The 'off' value results in the hcall-flush-required property set
> + * in the device tree for pseries machines. When 'off', the guest
> + * initiates explicit flush requests to the backend device ensuring
> + * write persistence.
> + */
> + bool sync_dax;
> +
> /*
> * The PPC64 - spapr requires each nvdimm device have a uuid.
> */
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 7c27fb3e2d..51c35488a4 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -333,6 +333,7 @@ struct SpaprMachineState {
> #define H_P7 -60
> #define H_P8 -61
> #define H_P9 -62
> +#define H_UNSUPPORTED -67
> #define H_OVERLAP -68
> #define H_UNSUPPORTED_FLAG -256
> #define H_MULTI_THREADS_ACTIVE -9005
>
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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