[PATCH 2/2] powerpc/pseries: Add driver for PAPR SCM regions
Dan Williams
dan.j.williams at intel.com
Sat Oct 13 09:36:55 AEDT 2018
On Tue, Oct 9, 2018 at 11:21 PM Oliver O'Halloran <oohall at gmail.com> wrote:
>
> Adds a driver that implements support for enabling and accessing PAPR
> SCM regions. Unfortunately due to how the PAPR interface works we can't
> use the existing of_pmem driver (yet) because:
>
> a) The guest is required to use the H_SCM_BIND_MEM h-call to add
> add the SCM region to it's physical address space, and
> b) There is currently no mechanism for relating a bare of_pmem region
> to the backing DIMM (or not-a-DIMM for our case).
>
> Both of these are easily handled by rolling the functionality into a
> seperate driver so here we are...
>
> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
> ---
> The alternative implementation here is that we have the pseries code
> do the h-calls and craft a pmem-region@<addr> node based on that.
> However, that doesn't solve b) and mpe has expressed his dislike of
> adding new stuff to the DT at runtime so i'd say that's a non-starter.
> ---
> arch/powerpc/platforms/pseries/Kconfig | 7 +
> arch/powerpc/platforms/pseries/Makefile | 1 +
> arch/powerpc/platforms/pseries/papr_scm.c | 340 ++++++++++++++++++++++++++++++
> 3 files changed, 348 insertions(+)
> create mode 100644 arch/powerpc/platforms/pseries/papr_scm.c
>
> diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
> index 0c698fd6d491..4b0fcb80efe5 100644
> --- a/arch/powerpc/platforms/pseries/Kconfig
> +++ b/arch/powerpc/platforms/pseries/Kconfig
> @@ -140,3 +140,10 @@ config IBMEBUS
> bool "Support for GX bus based adapters"
> help
> Bus device driver for GX bus based adapters.
> +
> +config PAPR_SCM
> + depends on PPC_PSERIES && MEMORY_HOTPLUG
> + select LIBNVDIMM
> + tristate "Support for the PAPR Storage Class Memory interface"
> + help
> + Enable access to hypervisor provided storage class memory.
> diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
> index 892b27ced973..a43ec843c8e2 100644
> --- a/arch/powerpc/platforms/pseries/Makefile
> +++ b/arch/powerpc/platforms/pseries/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_IO_EVENT_IRQ) += io_event_irq.o
> obj-$(CONFIG_LPARCFG) += lparcfg.o
> obj-$(CONFIG_IBMVIO) += vio.o
> obj-$(CONFIG_IBMEBUS) += ibmebus.o
> +obj-$(CONFIG_PAPR_SCM) += papr_scm.o
>
> ifdef CONFIG_PPC_PSERIES
> obj-$(CONFIG_SUSPEND) += suspend.o
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> new file mode 100644
> index 000000000000..87d4dbc18845
> --- /dev/null
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -0,0 +1,340 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#define pr_fmt(fmt) "papr-scm: " fmt
> +
> +#include <linux/of.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/ioport.h>
> +#include <linux/slab.h>
> +#include <linux/ndctl.h>
> +#include <linux/libnvdimm.h>
> +#include <linux/platform_device.h>
> +
> +#include <asm/plpar_wrappers.h>
> +
> +#define BIND_ANY_ADDR (~0ul)
> +
> +#define PAPR_SCM_DIMM_CMD_MASK \
> + ((1ul << ND_CMD_GET_CONFIG_SIZE) | \
> + (1ul << ND_CMD_GET_CONFIG_DATA) | \
> + (1ul << ND_CMD_SET_CONFIG_DATA))
> +
> +struct papr_scm_priv {
> + struct platform_device *pdev;
> + struct device_node *dn;
> + uint32_t drc_index;
> + uint64_t blocks;
> + uint64_t block_size;
> + int metadata_size;
> +
> + uint64_t bound_addr;
> +
> + struct nvdimm_bus_descriptor bus_desc;
> + struct nvdimm_bus *bus;
> + struct nvdimm *nvdimm;
> + struct resource res;
> + struct nd_region *region;
> + struct nd_interleave_set nd_set;
> +};
> +
> +static int drc_pmem_bind(struct papr_scm_priv *p)
> +{
> + unsigned long ret[PLPAR_HCALL_BUFSIZE];
> + uint64_t rc, token;
> +
> + /*
> + * When the hypervisor cannot map all the requested memory in a single
> + * hcall it returns H_BUSY and we call again with the token until
> + * we get H_SUCCESS. Aborting the retry loop before getting H_SUCCESS
> + * leave the system in an undefined state, so we wait.
> + */
> + token = 0;
> +
> + do {
> + rc = plpar_hcall(H_SCM_BIND_MEM, ret, p->drc_index, 0,
> + p->blocks, BIND_ANY_ADDR, token);
> + token = be64_to_cpu(ret[0]);
Does plpar_hcall sleep? Should there be a cond_resched() here if not?
> + } while (rc == H_BUSY);
> +
> + if (rc) {
> + dev_err(&p->pdev->dev, "bind err: %lld\n", rc);
> + return -ENXIO;
> + }
> +
> + p->bound_addr = be64_to_cpu(ret[1]);
> +
> + dev_dbg(&p->pdev->dev, "bound drc %x to %pR\n", p->drc_index, &p->res);
> +
> + return 0;
> +}
> +
> +static int drc_pmem_unbind(struct papr_scm_priv *p)
> +{
> + unsigned long ret[PLPAR_HCALL_BUFSIZE];
> + uint64_t rc, token;
> +
> + token = 0;
> +
> + /* NB: unbind has the same retry requirements mentioned above */
> + do {
> + rc = plpar_hcall(H_SCM_UNBIND_MEM, ret, p->drc_index,
> + p->bound_addr, p->blocks, token);
> + token = be64_to_cpu(ret);
...same busy loop comment.
> + } while (rc == H_BUSY);
> +
> + if (rc)
> + dev_err(&p->pdev->dev, "unbind error: %lld\n", rc);
> +
> + return !!rc;
> +}
> +
> +static int papr_scm_meta_get(struct papr_scm_priv *p,
> + struct nd_cmd_get_config_data_hdr *hdr)
> +{
> + unsigned long data[PLPAR_HCALL_BUFSIZE];
> + int64_t ret;
> +
> + if (hdr->in_offset >= p->metadata_size || hdr->in_length != 1)
> + return -EINVAL;
> +
> + ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
> + hdr->in_offset, 1);
> +
> + if (ret == H_PARAMETER) /* bad DRC index */
> + return -ENODEV;
> + if (ret)
> + return -EINVAL; /* other invalid parameter */
> +
> + hdr->out_buf[0] = data[0] & 0xff;
> +
> + return 0;
> +}
> +
> +static int papr_scm_meta_set(struct papr_scm_priv *p,
> + struct nd_cmd_set_config_hdr *hdr)
> +{
> + int64_t ret;
> +
> + if (hdr->in_offset >= p->metadata_size || hdr->in_length != 1)
> + return -EINVAL;
> +
> + ret = plpar_hcall_norets(H_SCM_WRITE_METADATA,
> + p->drc_index, hdr->in_offset, hdr->in_buf[0], 1);
> +
> + if (ret == H_PARAMETER) /* bad DRC index */
> + return -ENODEV;
> + if (ret)
> + return -EINVAL; /* other invalid parameter */
> +
> + return 0;
> +}
> +
> +int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
> + unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
> +{
> + struct nd_cmd_get_config_size *get_size_hdr;
> + struct papr_scm_priv *p;
> +
> + /* Only dimm-specific calls are supported atm */
> + if (!nvdimm)
> + return -EINVAL;
> +
> + p = nvdimm_provider_data(nvdimm);
> +
> + switch (cmd) {
> + case ND_CMD_GET_CONFIG_SIZE:
> + get_size_hdr = buf;
> +
> + get_size_hdr->status = 0;
> + get_size_hdr->max_xfer = 1;
> + get_size_hdr->config_size = p->metadata_size;
> + *cmd_rc = 0;
> + break;
> +
> + case ND_CMD_GET_CONFIG_DATA:
> + *cmd_rc = papr_scm_meta_get(p, buf);
> + break;
> +
> + case ND_CMD_SET_CONFIG_DATA:
> + *cmd_rc = papr_scm_meta_set(p, buf);
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
> +
> + return 0;
> +}
> +
> +static const struct attribute_group *region_attr_groups[] = {
> + &nd_region_attribute_group,
> + &nd_device_attribute_group,
> + &nd_mapping_attribute_group,
> + &nd_numa_attribute_group,
> + NULL,
> +};
> +
> +static const struct attribute_group *bus_attr_groups[] = {
> + &nvdimm_bus_attribute_group,
> + NULL,
> +};
> +
> +static const struct attribute_group *papr_scm_dimm_groups[] = {
> + &nvdimm_attribute_group,
> + &nd_device_attribute_group,
> + NULL,
> +};
> +
> +static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
> +{
> + struct device *dev = &p->pdev->dev;
> + struct nd_mapping_desc mapping;
> + struct nd_region_desc ndr_desc;
> + unsigned long dimm_flags;
> +
> + p->bus_desc.ndctl = papr_scm_ndctl;
> + p->bus_desc.module = THIS_MODULE;
> + p->bus_desc.of_node = p->pdev->dev.of_node;
> + p->bus_desc.attr_groups = bus_attr_groups;
> + p->bus_desc.provider_name = kstrdup(p->pdev->name, GFP_KERNEL);
> +
> + if (!p->bus_desc.provider_name)
> + return -ENOMEM;
> +
> + p->bus = nvdimm_bus_register(NULL, &p->bus_desc);
> + if (!p->bus) {
> + dev_err(dev, "Error creating nvdimm bus %pOF\n", p->dn);
> + return -ENXIO;
> + }
> +
> + dimm_flags = 0;
> + set_bit(NDD_ALIASING, &dimm_flags);
> +
> + p->nvdimm = nvdimm_create(p->bus, p, papr_scm_dimm_groups,
> + dimm_flags, PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
Looks good, although I'm just about to push out commits that change
this function signature to take a 'security_ops' pointer. If you need
a stable branch to base this on, let me know.
> + if (!p->nvdimm) {
> + dev_err(dev, "Error creating DIMM object for %pOF\n", p->dn);
> + goto err;
> + }
> +
> + /* now add the region */
> +
> + memset(&mapping, 0, sizeof(mapping));
> + mapping.nvdimm = p->nvdimm;
> + mapping.start = p->res.start;
> + mapping.size = p->blocks * p->block_size; // XXX: potential overflow?
Ideally, should be nvdimm relative addresses. Since you have just a
single DIMM per-region I would expect this to be 0 to
nvdimm->region_size. That said I don't think anything breaks if you
make the nvdimm address equal to the system-physical address, just
wanted to point out the intent. This only matters when you have
multiple DIMMs per region and need to record the per-DIMM contribution
in the labels on each DIMM.
Other than that looks ok to me:
Acked-by: Dan Williams <dan.j.williams at intel.com>
...just the matter of what to do about function signature change.
More information about the Linuxppc-dev
mailing list