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Subject[PATCH] acpi, nfit: rework NVDIMM leaf method detection
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Some BIOSen do not handle 0-byte transfer lengths for the _LSR and _LSW
(label storage read/write) methods. This causes Linux to fallback to the
deprecated _DSM path, or otherwise disable label support.

Introduce acpi_nvdimm_has_method() to detect whether a method is
available rather than calling the method, require _LSI and _LSR to be
paired, and require read support before enabling write support.

Cc: <stable@vger.kernel.org>
Fixes: 4b27db7e26cd ("acpi, nfit: add support for the _LS...")
Suggested-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/acpi/nfit/core.c | 41 +++++++++++++++++++++--------------------
drivers/acpi/nfit/nfit.h | 5 ++---
2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 4530d89044db..12fb414fa678 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -196,7 +196,7 @@ static int xlat_nvdimm_status(struct nvdimm *nvdimm, void *buf, unsigned int cmd
* In the _LSI, _LSR, _LSW case the locked status is
* communicated via the read/write commands
*/
- if (nfit_mem->has_lsi)
+ if (nfit_mem->has_lsr)
break;

if (status >> 16 & ND_CONFIG_LOCKED)
@@ -483,7 +483,7 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
min_t(u32, 256, in_buf.buffer.length), true);

/* call the BIOS, prefer the named methods over _DSM if available */
- if (nvdimm && cmd == ND_CMD_GET_CONFIG_SIZE && nfit_mem->has_lsi)
+ if (nvdimm && cmd == ND_CMD_GET_CONFIG_SIZE && nfit_mem->has_lsr)
out_obj = acpi_label_info(handle);
else if (nvdimm && cmd == ND_CMD_GET_CONFIG_DATA && nfit_mem->has_lsr) {
struct nd_cmd_get_config_data_hdr *p = buf;
@@ -1653,12 +1653,23 @@ static void acpi_nvdimm_notify(acpi_handle handle, u32 event, void *data)
device_unlock(dev->parent);
}

+static bool acpi_nvdimm_has_method(struct acpi_device *adev, char *method)
+{
+ acpi_handle handle;
+ acpi_status status;
+
+ status = acpi_get_handle(adev->handle, method, &handle);
+
+ if (ACPI_SUCCESS(status))
+ return true;
+ return false;
+}
+
static int acpi_nfit_add_dimm(struct acpi_nfit_desc *acpi_desc,
struct nfit_mem *nfit_mem, u32 device_handle)
{
struct acpi_device *adev, *adev_dimm;
struct device *dev = acpi_desc->dev;
- union acpi_object *obj;
unsigned long dsm_mask;
const guid_t *guid;
int i;
@@ -1731,25 +1742,15 @@ static int acpi_nfit_add_dimm(struct acpi_nfit_desc *acpi_desc,
1ULL << i))
set_bit(i, &nfit_mem->dsm_mask);

- obj = acpi_label_info(adev_dimm->handle);
- if (obj) {
- ACPI_FREE(obj);
- nfit_mem->has_lsi = 1;
- dev_dbg(dev, "%s: has _LSI\n", dev_name(&adev_dimm->dev));
- }
-
- obj = acpi_label_read(adev_dimm->handle, 0, 0);
- if (obj) {
- ACPI_FREE(obj);
- nfit_mem->has_lsr = 1;
+ if (acpi_nvdimm_has_method(adev_dimm, "_LSI")
+ && acpi_nvdimm_has_method(adev_dimm, "_LSR")) {
dev_dbg(dev, "%s: has _LSR\n", dev_name(&adev_dimm->dev));
+ nfit_mem->has_lsr = true;
}

- obj = acpi_label_write(adev_dimm->handle, 0, 0, NULL);
- if (obj) {
- ACPI_FREE(obj);
- nfit_mem->has_lsw = 1;
+ if (nfit_mem->has_lsr && acpi_nvdimm_has_method(adev_dimm, "_LSW")) {
dev_dbg(dev, "%s: has _LSW\n", dev_name(&adev_dimm->dev));
+ nfit_mem->has_lsw = true;
}

return 0;
@@ -1838,10 +1839,10 @@ static int acpi_nfit_register_dimms(struct acpi_nfit_desc *acpi_desc)
cmd_mask |= nfit_mem->dsm_mask & NVDIMM_STANDARD_CMDMASK;
}

- if (nfit_mem->has_lsi)
+ if (nfit_mem->has_lsr) {
set_bit(ND_CMD_GET_CONFIG_SIZE, &cmd_mask);
- if (nfit_mem->has_lsr)
set_bit(ND_CMD_GET_CONFIG_DATA, &cmd_mask);
+ }
if (nfit_mem->has_lsw)
set_bit(ND_CMD_SET_CONFIG_DATA, &cmd_mask);

diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index 50d36e166d70..ac9c49463731 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -171,9 +171,8 @@ struct nfit_mem {
struct resource *flush_wpq;
unsigned long dsm_mask;
int family;
- u32 has_lsi:1;
- u32 has_lsr:1;
- u32 has_lsw:1;
+ bool has_lsr;
+ bool has_lsw;
};

struct acpi_nfit_desc {
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