| Message ID | 293ee143dcabb386ca06b384a384171c256a2ecc.1498810220.git.jerry.hoemann@hpe.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > Add a bus level dsm_mask to nvdimm_bus_descriptor to allow the passthru > calling mechanism to specify a different mask from the cmd_mask. > > Populate bus_dsm_mask and use it to filter dsm calls that user can > make through the pass thru interface. > > Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com> > --- > drivers/acpi/nfit/core.c | 8 ++++++++ > include/linux/libnvdimm.h | 1 + > 2 files changed, 9 insertions(+) > > diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c > index b46fca2..5e4c137 100644 > --- a/drivers/acpi/nfit/core.c > +++ b/drivers/acpi/nfit/core.c > @@ -253,6 +253,8 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm, > cmd_name = nvdimm_bus_cmd_name(cmd); > cmd_mask = nd_desc->cmd_mask; > dsm_mask = cmd_mask; > + if (cmd == ND_CMD_CALL) > + dsm_mask = nd_desc->bus_dsm_mask; > desc = nd_cmd_bus_desc(cmd); > uuid = to_nfit_uuid(NFIT_DEV_BUS); > handle = adev->handle; > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); > struct acpi_device *adev; > + unsigned long dsm_mask; > int i; > > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) > set_bit(i, &nd_desc->cmd_mask); > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); > + > + dsm_mask = 0x3bf; I went ahead and fixed this up to use dsm_mask defined like this: + dsm_mask = + (1 << ND_CMD_ARS_CAP) | + (1 << ND_CMD_ARS_START) | + (1 << ND_CMD_ARS_STATUS) | + (1 << ND_CMD_CLEAR_ERROR) | + (1 << NFIT_CMD_TRANSLATE_SPA) | + (1 << NFIT_CMD_ARS_INJECT_SET) | + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | + (1 << NFIT_CMD_ARS_INJECT_GET); This drops function number 0 which userspace has no need to call.
On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: ... > On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > > + if (cmd == ND_CMD_CALL) > > + dsm_mask = nd_desc->bus_dsm_mask; > > desc = nd_cmd_bus_desc(cmd); > > uuid = to_nfit_uuid(NFIT_DEV_BUS); > > handle = adev->handle; > > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; > > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); > > struct acpi_device *adev; > > + unsigned long dsm_mask; > > int i; > > > > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; > > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) > > set_bit(i, &nd_desc->cmd_mask); > > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); > > + > > + dsm_mask = 0x3bf; > > I went ahead and fixed this up to use dsm_mask defined like this: > > + dsm_mask = > + (1 << ND_CMD_ARS_CAP) | > + (1 << ND_CMD_ARS_START) | > + (1 << ND_CMD_ARS_STATUS) | > + (1 << ND_CMD_CLEAR_ERROR) | > + (1 << NFIT_CMD_TRANSLATE_SPA) | > + (1 << NFIT_CMD_ARS_INJECT_SET) | > + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | > + (1 << NFIT_CMD_ARS_INJECT_GET); > > This drops function number 0 which userspace has no need to call. Actually I like to call function 0. Its an excellent test when modifying the code path as its a no side effects function whose output is known in advance and instantly recognizable. I also use it when testing new firmware. What is the downside to allowing it? What bad things happen? Also, I do have to ask why you allow function zero for NVDIMM_FAMILY_MSFT?
On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > > ... > >> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> > + if (cmd == ND_CMD_CALL) >> > + dsm_mask = nd_desc->bus_dsm_mask; >> > desc = nd_cmd_bus_desc(cmd); >> > uuid = to_nfit_uuid(NFIT_DEV_BUS); >> > handle = adev->handle; >> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; >> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); >> > struct acpi_device *adev; >> > + unsigned long dsm_mask; >> > int i; >> > >> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; >> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) >> > set_bit(i, &nd_desc->cmd_mask); >> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); >> > + >> > + dsm_mask = 0x3bf; >> >> I went ahead and fixed this up to use dsm_mask defined like this: >> >> + dsm_mask = >> + (1 << ND_CMD_ARS_CAP) | >> + (1 << ND_CMD_ARS_START) | >> + (1 << ND_CMD_ARS_STATUS) | >> + (1 << ND_CMD_CLEAR_ERROR) | >> + (1 << NFIT_CMD_TRANSLATE_SPA) | >> + (1 << NFIT_CMD_ARS_INJECT_SET) | >> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | >> + (1 << NFIT_CMD_ARS_INJECT_GET); >> >> This drops function number 0 which userspace has no need to call. > > Actually I like to call function 0. Its an excellent test when > modifying the code path as its a no side effects function whose output > is known in advance and instantly recognizable. I also use it when > testing new firmware. > > What is the downside to allowing it? What bad things happen? It allows implementations to bypass the standardization process and ship new root DSMs. It's always possible to patch the kernel locally for development, so I see no reason to ship this capability globally. > Also, I do have to ask why you allow function zero for NVDIMM_FAMILY_MSFT? Yeah, that's an oversight / mistake, but it's also benign since it can't be used to add support for new function numbers to the family since all 32 numbers are already taken. We also allow override for leaf devices since there's quite a bit more per vendor differentiation that might take a while to standardize.
On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: >> >> ... >> >>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >>> > + if (cmd == ND_CMD_CALL) >>> > + dsm_mask = nd_desc->bus_dsm_mask; >>> > desc = nd_cmd_bus_desc(cmd); >>> > uuid = to_nfit_uuid(NFIT_DEV_BUS); >>> > handle = adev->handle; >>> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >>> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; >>> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); >>> > struct acpi_device *adev; >>> > + unsigned long dsm_mask; >>> > int i; >>> > >>> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; >>> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >>> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) >>> > set_bit(i, &nd_desc->cmd_mask); >>> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); >>> > + >>> > + dsm_mask = 0x3bf; >>> >>> I went ahead and fixed this up to use dsm_mask defined like this: >>> >>> + dsm_mask = >>> + (1 << ND_CMD_ARS_CAP) | >>> + (1 << ND_CMD_ARS_START) | >>> + (1 << ND_CMD_ARS_STATUS) | >>> + (1 << ND_CMD_CLEAR_ERROR) | >>> + (1 << NFIT_CMD_TRANSLATE_SPA) | >>> + (1 << NFIT_CMD_ARS_INJECT_SET) | >>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | >>> + (1 << NFIT_CMD_ARS_INJECT_GET); >>> >>> This drops function number 0 which userspace has no need to call. >> >> Actually I like to call function 0. Its an excellent test when >> modifying the code path as its a no side effects function whose output >> is known in advance and instantly recognizable. I also use it when >> testing new firmware. >> >> What is the downside to allowing it? What bad things happen? > > It allows implementations to bypass the standardization process and > ship new root DSMs. It's always possible to patch the kernel locally > for development, so I see no reason to ship this capability globally. Actually, just the discovery portion does not lead to this leak, but it's redundant when we have the 'dsm_mask' sysfs attribute.
On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: > On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: > > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > >> > >> ... > >> > >>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >>> > + if (cmd == ND_CMD_CALL) > >>> > + dsm_mask = nd_desc->bus_dsm_mask; > >>> > desc = nd_cmd_bus_desc(cmd); > >>> > uuid = to_nfit_uuid(NFIT_DEV_BUS); > >>> > handle = adev->handle; > >>> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > >>> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; > >>> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); > >>> > struct acpi_device *adev; > >>> > + unsigned long dsm_mask; > >>> > int i; > >>> > > >>> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; > >>> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > >>> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) > >>> > set_bit(i, &nd_desc->cmd_mask); > >>> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); > >>> > + > >>> > + dsm_mask = 0x3bf; > >>> > >>> I went ahead and fixed this up to use dsm_mask defined like this: > >>> > >>> + dsm_mask = > >>> + (1 << ND_CMD_ARS_CAP) | > >>> + (1 << ND_CMD_ARS_START) | > >>> + (1 << ND_CMD_ARS_STATUS) | > >>> + (1 << ND_CMD_CLEAR_ERROR) | > >>> + (1 << NFIT_CMD_TRANSLATE_SPA) | > >>> + (1 << NFIT_CMD_ARS_INJECT_SET) | > >>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | > >>> + (1 << NFIT_CMD_ARS_INJECT_GET); > >>> > >>> This drops function number 0 which userspace has no need to call. > >> > >> Actually I like to call function 0. Its an excellent test when > >> modifying the code path as its a no side effects function whose output > >> is known in advance and instantly recognizable. I also use it when > >> testing new firmware. > >> > >> What is the downside to allowing it? What bad things happen? > > > > It allows implementations to bypass the standardization process and > > ship new root DSMs. It's always possible to patch the kernel locally > > for development, so I see no reason to ship this capability globally. I don't understand this comment, but I think your next comment essentially says to disregard this comment? > > Actually, just the discovery portion does not lead to this leak, but > it's redundant when we have the 'dsm_mask' sysfs attribute. No. The generation of the mask in sysfs is not done by executing the code in acpi_nfit_ctl. One of the reasons I call function 0 to test changes I am making to the ioctl path itself. The sysfs has nothing to do with that path and cannot be used to serve this purpose. And since the content of sysfs has been edited it also can not be used as a basic test of firmware. What is the downside to allowing the calling of function 0?
On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: >> >> >> >> ... >> >> >> >>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> >>> > + if (cmd == ND_CMD_CALL) >> >>> > + dsm_mask = nd_desc->bus_dsm_mask; >> >>> > desc = nd_cmd_bus_desc(cmd); >> >>> > uuid = to_nfit_uuid(NFIT_DEV_BUS); >> >>> > handle = adev->handle; >> >>> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> >>> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; >> >>> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); >> >>> > struct acpi_device *adev; >> >>> > + unsigned long dsm_mask; >> >>> > int i; >> >>> > >> >>> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; >> >>> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> >>> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) >> >>> > set_bit(i, &nd_desc->cmd_mask); >> >>> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); >> >>> > + >> >>> > + dsm_mask = 0x3bf; >> >>> >> >>> I went ahead and fixed this up to use dsm_mask defined like this: >> >>> >> >>> + dsm_mask = >> >>> + (1 << ND_CMD_ARS_CAP) | >> >>> + (1 << ND_CMD_ARS_START) | >> >>> + (1 << ND_CMD_ARS_STATUS) | >> >>> + (1 << ND_CMD_CLEAR_ERROR) | >> >>> + (1 << NFIT_CMD_TRANSLATE_SPA) | >> >>> + (1 << NFIT_CMD_ARS_INJECT_SET) | >> >>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | >> >>> + (1 << NFIT_CMD_ARS_INJECT_GET); >> >>> >> >>> This drops function number 0 which userspace has no need to call. >> >> >> >> Actually I like to call function 0. Its an excellent test when >> >> modifying the code path as its a no side effects function whose output >> >> is known in advance and instantly recognizable. I also use it when >> >> testing new firmware. >> >> >> >> What is the downside to allowing it? What bad things happen? >> > >> > It allows implementations to bypass the standardization process and >> > ship new root DSMs. It's always possible to patch the kernel locally >> > for development, so I see no reason to ship this capability globally. > > I don't understand this comment, but I think your next comment > essentially says to disregard this comment? Yes, sorry. >> Actually, just the discovery portion does not lead to this leak, but >> it's redundant when we have the 'dsm_mask' sysfs attribute. > > No. The generation of the mask in sysfs is not done by > executing the code in acpi_nfit_ctl. One of the reasons I call > function 0 to test changes I am making to the ioctl path itself. > The sysfs has nothing to do with that path and cannot be used > to serve this purpose. > > And since the content of sysfs has been edited it also can not be > used as a basic test of firmware. > > What is the downside to allowing the calling of function 0? It needlessly expands the kernel ABI. I would suggest, if you want to test acpi_nfit_ctl() path changes, expand the existing test infrastructure we have in nfit_ctl_test(). If you want to test firmware you don't need the upstream kernel to carry firmware debug enabling in the production path, but I would support expanding tools/testing/nvdimm/ to make it easier to test firmware.
On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: > On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: > >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: > >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > >> >> > >> >> ... > >> >> > >> >>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> >>> > + if (cmd == ND_CMD_CALL) > >> >>> > + dsm_mask = nd_desc->bus_dsm_mask; > >> >>> > desc = nd_cmd_bus_desc(cmd); > >> >>> > uuid = to_nfit_uuid(NFIT_DEV_BUS); > >> >>> > handle = adev->handle; > >> >>> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > >> >>> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; > >> >>> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); > >> >>> > struct acpi_device *adev; > >> >>> > + unsigned long dsm_mask; > >> >>> > int i; > >> >>> > > >> >>> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; > >> >>> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) > >> >>> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) > >> >>> > set_bit(i, &nd_desc->cmd_mask); > >> >>> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); > >> >>> > + > >> >>> > + dsm_mask = 0x3bf; > >> >>> > >> >>> I went ahead and fixed this up to use dsm_mask defined like this: > >> >>> > >> >>> + dsm_mask = > >> >>> + (1 << ND_CMD_ARS_CAP) | > >> >>> + (1 << ND_CMD_ARS_START) | > >> >>> + (1 << ND_CMD_ARS_STATUS) | > >> >>> + (1 << ND_CMD_CLEAR_ERROR) | > >> >>> + (1 << NFIT_CMD_TRANSLATE_SPA) | > >> >>> + (1 << NFIT_CMD_ARS_INJECT_SET) | > >> >>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | > >> >>> + (1 << NFIT_CMD_ARS_INJECT_GET); > >> >>> > >> >>> This drops function number 0 which userspace has no need to call. > >> >> > >> >> Actually I like to call function 0. Its an excellent test when > >> >> modifying the code path as its a no side effects function whose output > >> >> is known in advance and instantly recognizable. I also use it when > >> >> testing new firmware. > >> >> > >> >> What is the downside to allowing it? What bad things happen? > >> > > >> > It allows implementations to bypass the standardization process and > >> > ship new root DSMs. It's always possible to patch the kernel locally > >> > for development, so I see no reason to ship this capability globally. > > > > I don't understand this comment, but I think your next comment > > essentially says to disregard this comment? > > Yes, sorry. > > >> Actually, just the discovery portion does not lead to this leak, but > >> it's redundant when we have the 'dsm_mask' sysfs attribute. > > > > No. The generation of the mask in sysfs is not done by > > executing the code in acpi_nfit_ctl. One of the reasons I call > > function 0 to test changes I am making to the ioctl path itself. > > The sysfs has nothing to do with that path and cannot be used > > to serve this purpose. > > > > And since the content of sysfs has been edited it also can not be > > used as a basic test of firmware. > > > > What is the downside to allowing the calling of function 0? > > It needlessly expands the kernel ABI. I would suggest, if you want to No. It is not needless. It is not an ABI extension. Same goes for the override feature. I hope that ACPI doesn't extend the specification in the future because we'll just have to redo these patches yet again.
On Tue, Jul 4, 2017 at 1:08 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: >> On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: >> >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: >> >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: >> >> >> >> >> >> ... >> >> >> >> >> >>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> >> >>> > + if (cmd == ND_CMD_CALL) >> >> >>> > + dsm_mask = nd_desc->bus_dsm_mask; >> >> >>> > desc = nd_cmd_bus_desc(cmd); >> >> >>> > uuid = to_nfit_uuid(NFIT_DEV_BUS); >> >> >>> > handle = adev->handle; >> >> >>> > @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> >> >>> > struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; >> >> >>> > const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); >> >> >>> > struct acpi_device *adev; >> >> >>> > + unsigned long dsm_mask; >> >> >>> > int i; >> >> >>> > >> >> >>> > nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; >> >> >>> > @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >> >> >>> > if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) >> >> >>> > set_bit(i, &nd_desc->cmd_mask); >> >> >>> > set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); >> >> >>> > + >> >> >>> > + dsm_mask = 0x3bf; >> >> >>> >> >> >>> I went ahead and fixed this up to use dsm_mask defined like this: >> >> >>> >> >> >>> + dsm_mask = >> >> >>> + (1 << ND_CMD_ARS_CAP) | >> >> >>> + (1 << ND_CMD_ARS_START) | >> >> >>> + (1 << ND_CMD_ARS_STATUS) | >> >> >>> + (1 << ND_CMD_CLEAR_ERROR) | >> >> >>> + (1 << NFIT_CMD_TRANSLATE_SPA) | >> >> >>> + (1 << NFIT_CMD_ARS_INJECT_SET) | >> >> >>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | >> >> >>> + (1 << NFIT_CMD_ARS_INJECT_GET); >> >> >>> >> >> >>> This drops function number 0 which userspace has no need to call. >> >> >> >> >> >> Actually I like to call function 0. Its an excellent test when >> >> >> modifying the code path as its a no side effects function whose output >> >> >> is known in advance and instantly recognizable. I also use it when >> >> >> testing new firmware. >> >> >> >> >> >> What is the downside to allowing it? What bad things happen? >> >> > >> >> > It allows implementations to bypass the standardization process and >> >> > ship new root DSMs. It's always possible to patch the kernel locally >> >> > for development, so I see no reason to ship this capability globally. >> > >> > I don't understand this comment, but I think your next comment >> > essentially says to disregard this comment? >> >> Yes, sorry. >> >> >> Actually, just the discovery portion does not lead to this leak, but >> >> it's redundant when we have the 'dsm_mask' sysfs attribute. >> > >> > No. The generation of the mask in sysfs is not done by >> > executing the code in acpi_nfit_ctl. One of the reasons I call >> > function 0 to test changes I am making to the ioctl path itself. >> > The sysfs has nothing to do with that path and cannot be used >> > to serve this purpose. >> > >> > And since the content of sysfs has been edited it also can not be >> > used as a basic test of firmware. >> > >> > What is the downside to allowing the calling of function 0? >> >> It needlessly expands the kernel ABI. I would suggest, if you want to > > No. It is not needless. It is not an ABI extension. > Same goes for the override feature. If the need is testing then we have a tools/testing/nvdimm for that. Of course it's an ABI extension, it allows userspace to discover DSM function numbers the kernel didn't know about at compile time. > I hope that ACPI doesn't extend the specification in the future because > we'll just have to redo these patches yet again. Hopefully this is the last ACPI spec version where we add new DSMs to the root device. All future methods should be named methods like what the specification started doing for NVIDMM leaf devices with _LSI, _LSR, and _LSW.
On 07/04/2017 04:37 PM, Dan Williams wrote: > On Tue, Jul 4, 2017 at 1:08 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: >>> On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >>>> On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: >>>>> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: >>>>>> On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >>>>>>> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: >>>>>>> >>>>>>> ... >>>>>>> >>>>>>>> On Fri, Jun 30, 2017 at 9:09 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >>>>>>>>> + if (cmd == ND_CMD_CALL) >>>>>>>>> + dsm_mask = nd_desc->bus_dsm_mask; >>>>>>>>> desc = nd_cmd_bus_desc(cmd); >>>>>>>>> uuid = to_nfit_uuid(NFIT_DEV_BUS); >>>>>>>>> handle = adev->handle; >>>>>>>>> @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >>>>>>>>> struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; >>>>>>>>> const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); >>>>>>>>> struct acpi_device *adev; >>>>>>>>> + unsigned long dsm_mask; >>>>>>>>> int i; >>>>>>>>> >>>>>>>>> nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; >>>>>>>>> @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) >>>>>>>>> if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) >>>>>>>>> set_bit(i, &nd_desc->cmd_mask); >>>>>>>>> set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); >>>>>>>>> + >>>>>>>>> + dsm_mask = 0x3bf; >>>>>>>> >>>>>>>> I went ahead and fixed this up to use dsm_mask defined like this: >>>>>>>> >>>>>>>> + dsm_mask = >>>>>>>> + (1 << ND_CMD_ARS_CAP) | >>>>>>>> + (1 << ND_CMD_ARS_START) | >>>>>>>> + (1 << ND_CMD_ARS_STATUS) | >>>>>>>> + (1 << ND_CMD_CLEAR_ERROR) | >>>>>>>> + (1 << NFIT_CMD_TRANSLATE_SPA) | >>>>>>>> + (1 << NFIT_CMD_ARS_INJECT_SET) | >>>>>>>> + (1 << NFIT_CMD_ARS_INJECT_CLEAR) | >>>>>>>> + (1 << NFIT_CMD_ARS_INJECT_GET); >>>>>>>> >>>>>>>> This drops function number 0 which userspace has no need to call. >>>>>>> >>>>>>> Actually I like to call function 0. Its an excellent test when >>>>>>> modifying the code path as its a no side effects function whose output >>>>>>> is known in advance and instantly recognizable. I also use it when >>>>>>> testing new firmware. >>>>>>> >>>>>>> What is the downside to allowing it? What bad things happen? >>>>>> >>>>>> It allows implementations to bypass the standardization process and >>>>>> ship new root DSMs. It's always possible to patch the kernel locally >>>>>> for development, so I see no reason to ship this capability globally. >>>> >>>> I don't understand this comment, but I think your next comment >>>> essentially says to disregard this comment? >>> >>> Yes, sorry. >>> >>>>> Actually, just the discovery portion does not lead to this leak, but >>>>> it's redundant when we have the 'dsm_mask' sysfs attribute. >>>> >>>> No. The generation of the mask in sysfs is not done by >>>> executing the code in acpi_nfit_ctl. One of the reasons I call >>>> function 0 to test changes I am making to the ioctl path itself. >>>> The sysfs has nothing to do with that path and cannot be used >>>> to serve this purpose. >>>> >>>> And since the content of sysfs has been edited it also can not be >>>> used as a basic test of firmware. >>>> >>>> What is the downside to allowing the calling of function 0? >>> >>> It needlessly expands the kernel ABI. I would suggest, if you want to >> >> No. It is not needless. It is not an ABI extension. >> Same goes for the override feature. I have never understood why allowing function 0 is considered harmful. It is a standard function defined by ACPI in general and specifically for NVDIMM Rood Device _DSMs. It is also defined for each vendor-specific DSM family. It is not an ABI extension. It is a standard. > If the need is testing then we have a tools/testing/nvdimm for that. > Of course it's an ABI extension, it allows userspace to discover DSM > function numbers the kernel didn't know about at compile time. It also allows user space to determine which DSMs are actually supported by the platform, which may be a subset of the defined set, in a standard way. Exposing information only in /sys just makes it harder for people writing software (tools, tests, whatever) that need to support more than just Linux. >> I hope that ACPI doesn't extend the specification in the future because >> we'll just have to redo these patches yet again. > > Hopefully this is the last ACPI spec version where we add new DSMs to > the root device. I wouldn't bet on it. > All future methods should be named methods like what > the specification started doing for NVIDMM leaf devices with _LSI, > _LSR, and _LSW. Those methods started out as DSMs for a specific vendor and then became standardized. It would not surprise me if that's the path that is taken as new NVDIMM technologies evolve and new functions may be required. It's not always clear on the outset what should be standardized. Aggressively preventing extensibility, especially when it's actually part of a standard, baffles me. -- ljk > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm >
On Tue, Jul 04, 2017 at 01:37:43PM -0700, Dan Williams wrote: > On Tue, Jul 4, 2017 at 1:08 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > > On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: > >> On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: > >> >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: > >> >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > >> >> >> > >> >> >> ... ... > >> >> >>> > >> >> >>> This drops function number 0 which userspace has no need to call. > >> >> >> > >> >> >> Actually I like to call function 0. Its an excellent test when > >> >> >> modifying the code path as its a no side effects function whose output > >> >> >> is known in advance and instantly recognizable. I also use it when > >> >> >> testing new firmware. > >> >> >> > >> >> >> What is the downside to allowing it? What bad things happen? > >> >> > > >> >> > It allows implementations to bypass the standardization process and > >> >> > ship new root DSMs. It's always possible to patch the kernel locally > >> >> > for development, so I see no reason to ship this capability globally. > >> > > >> > I don't understand this comment, but I think your next comment > >> > essentially says to disregard this comment? > >> > >> Yes, sorry. > >> > >> >> Actually, just the discovery portion does not lead to this leak, but > >> >> it's redundant when we have the 'dsm_mask' sysfs attribute. > >> > > >> > No. The generation of the mask in sysfs is not done by > >> > executing the code in acpi_nfit_ctl. One of the reasons I call > >> > function 0 to test changes I am making to the ioctl path itself. > >> > The sysfs has nothing to do with that path and cannot be used > >> > to serve this purpose. > >> > > >> > And since the content of sysfs has been edited it also can not be > >> > used as a basic test of firmware. > >> > > >> > What is the downside to allowing the calling of function 0? > >> > >> It needlessly expands the kernel ABI. I would suggest, if you want to > > > > No. It is not needless. It is not an ABI extension. > > Same goes for the override feature. > > If the need is testing then we have a tools/testing/nvdimm for that. > Of course it's an ABI extension, it allows userspace to discover DSM > function numbers the kernel didn't know about at compile time. A modification to a library or kernel that changes the results of a function (or system call) doesn't necessarily break (or extend) an ABI. An obvious example is that of a random number generator function. A library/kernel is completely free to change the implementation of the random number generator (and the values it returns) without breaking the ABI provided all other rules of ABI preservation are followed. Now lets look at problem at hand. The pass thru mechanism has very little semantic overhead. Fill in the nd_cmd_pkg as described in ndctl.h, call the ioctl w/ argument with ND_CMD_CALL, and the kernel will marshal up the arguments, call the DSM and return the results. The values of nd_command could be any value and it is for the DSM to either accept or reject the input argument. I wrote this interface and this is how I defined it. The user application is not changing irrespective of if the kernel applies a mask to the passed in nd_command argument. The data structures are not changing at either source level or binary level. The calling convention is not changing. No object file changes are required. Nothing related to ABI preservation is impacted. The only question is whether the application of a mask to special case function 0 breaks/extends the ABI. It turns out that this point doesn't really matter as your position is invalid either way. The argument for this not being an API breakage/extension: A DSM could either implement or not a function index for any value of N. So, a correctly written application must take into account that for any value of N, the DSM may return error or not. Preserving an ABI doesn't require the library/kernel preserve incorrect application behavior. Now, assume that the special casing of function zero does constitute a breakage/extension of the ABI: I'm not the one wishing to special case function 0, you are. So, to this point I say, Dan please don't make needless extension to the ABI. Its and extension and you've provided no valid reason for making it. Your argument to disallow function zero is invalid. There is nothing harmful per se to allow function 0. All DSMs that return non zero are required to have it. By excluding it, you actually create the impression that the underlying DSM is violating the DSM specification.
On Wed, Jul 5, 2017 at 9:24 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > On Tue, Jul 04, 2017 at 01:37:43PM -0700, Dan Williams wrote: >> On Tue, Jul 4, 2017 at 1:08 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> > On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: >> >> On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> >> > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: >> >> >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: >> >> >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: >> >> >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: >> >> >> >> >> >> >> >> ... > > ... > >> >> >> >>> >> >> >> >>> This drops function number 0 which userspace has no need to call. >> >> >> >> >> >> >> >> Actually I like to call function 0. Its an excellent test when >> >> >> >> modifying the code path as its a no side effects function whose output >> >> >> >> is known in advance and instantly recognizable. I also use it when >> >> >> >> testing new firmware. >> >> >> >> >> >> >> >> What is the downside to allowing it? What bad things happen? >> >> >> > >> >> >> > It allows implementations to bypass the standardization process and >> >> >> > ship new root DSMs. It's always possible to patch the kernel locally >> >> >> > for development, so I see no reason to ship this capability globally. >> >> > >> >> > I don't understand this comment, but I think your next comment >> >> > essentially says to disregard this comment? >> >> >> >> Yes, sorry. >> >> >> >> >> Actually, just the discovery portion does not lead to this leak, but >> >> >> it's redundant when we have the 'dsm_mask' sysfs attribute. >> >> > >> >> > No. The generation of the mask in sysfs is not done by >> >> > executing the code in acpi_nfit_ctl. One of the reasons I call >> >> > function 0 to test changes I am making to the ioctl path itself. >> >> > The sysfs has nothing to do with that path and cannot be used >> >> > to serve this purpose. >> >> > >> >> > And since the content of sysfs has been edited it also can not be >> >> > used as a basic test of firmware. >> >> > >> >> > What is the downside to allowing the calling of function 0? >> >> >> >> It needlessly expands the kernel ABI. I would suggest, if you want to >> > >> > No. It is not needless. It is not an ABI extension. >> > Same goes for the override feature. >> >> If the need is testing then we have a tools/testing/nvdimm for that. > > > >> Of course it's an ABI extension, it allows userspace to discover DSM >> function numbers the kernel didn't know about at compile time. > > > A modification to a library or kernel that changes the results of a > function (or system call) doesn't necessarily break (or extend) an ABI. > An obvious example is that of a random number generator function. > A library/kernel is completely free to change the implementation > of the random number generator (and the values it returns) > without breaking the ABI provided all other rules of ABI preservation > are followed. > > Now lets look at problem at hand. The pass thru mechanism has very > little semantic overhead. Fill in the nd_cmd_pkg as described in ndctl.h, > call the ioctl w/ argument with ND_CMD_CALL, and the kernel will marshal > up the arguments, call the DSM and return the results. The values > of nd_command could be any value and it is for the DSM to either accept > or reject the input argument. I wrote this interface and this is how > I defined it. > > The user application is not changing irrespective of if the kernel applies > a mask to the passed in nd_command argument. The data structures are not > changing at either source level or binary level. The calling convention is not > changing. No object file changes are required. Nothing related to ABI > preservation is impacted. The only question is whether the application > of a mask to special case function 0 breaks/extends the ABI. > > It turns out that this point doesn't really matter as your position > is invalid either way. > > The argument for this not being an API breakage/extension: > > A DSM could either implement or not a function index for any value of N. > So, a correctly written application must take into account that for > any value of N, the DSM may return error or not. Preserving an ABI > doesn't require the library/kernel preserve incorrect application > behavior. > > Now, assume that the special casing of function zero does constitute > a breakage/extension of the ABI: > > I'm not the one wishing to special case function 0, you are. > So, to this point I say, Dan please don't make needless extension to > the ABI. Its and extension and you've provided no valid reason > for making it. > > Your argument to disallow function zero is invalid. > > There is nothing harmful per se to allow function 0. All DSMs that return > non zero are required to have it. By excluding it, you actually create the > impression that the underlying DSM is violating the DSM specification. This goes back to the original reasoning for pushing back on the override for the leaf-level _DSM methods. Specifically the ability to bypass the standardization process to ship vendor-specific behavior. Now, the other side of the argument is that if the next spec adds new _DSMs a simple override can enable them. I am more sympathetic to the override for the leaf / DIMM level because those _DSMs truly are DIMM-vendor specific, but the root device is not. Also, none of the root-level DSMs added for 6.2 are in any way critical for proper operation of the platform, and I do not see any bus-level functionality on the horizon that we need to aggressively pre-enable. It was a mistake to use _DSM for common root-level functionality, and we shouldn't double down on that mistake by allowing unfettered definition of new interfaces. NVDIMM is not so special that it needs to bypass the standard ACPI-to-kernel development pipeline.
On Wed, Jul 05, 2017 at 09:35:48AM -0700, Dan Williams wrote: > On Wed, Jul 5, 2017 at 9:24 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > > On Tue, Jul 04, 2017 at 01:37:43PM -0700, Dan Williams wrote: > >> On Tue, Jul 4, 2017 at 1:08 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> > On Sat, Jul 01, 2017 at 01:46:03PM -0700, Dan Williams wrote: > >> >> On Sat, Jul 1, 2017 at 1:38 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> >> > On Sat, Jul 01, 2017 at 01:10:31PM -0700, Dan Williams wrote: > >> >> >> On Sat, Jul 1, 2017 at 1:08 PM, Dan Williams <dan.j.williams@intel.com> wrote: > >> >> >> > On Sat, Jul 1, 2017 at 12:58 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > >> >> >> >> On Fri, Jun 30, 2017 at 08:55:22PM -0700, Dan Williams wrote: > >> >> >> >> > >> >> >> >> ... > > > > ... > > > >> >> >> >>> > >> >> >> >>> This drops function number 0 which userspace has no need to call. > >> >> >> >> > >> >> >> >> Actually I like to call function 0. Its an excellent test when > >> >> >> >> modifying the code path as its a no side effects function whose output > >> >> >> >> is known in advance and instantly recognizable. I also use it when > >> >> >> >> testing new firmware. > >> >> >> >> > >> >> >> >> What is the downside to allowing it? What bad things happen? > >> >> >> > > >> >> >> > It allows implementations to bypass the standardization process and > >> >> >> > ship new root DSMs. It's always possible to patch the kernel locally > >> >> >> > for development, so I see no reason to ship this capability globally. > >> >> > > >> >> > I don't understand this comment, but I think your next comment > >> >> > essentially says to disregard this comment? > >> >> > >> >> Yes, sorry. > >> >> > >> >> >> Actually, just the discovery portion does not lead to this leak, but > >> >> >> it's redundant when we have the 'dsm_mask' sysfs attribute. > >> >> > > >> >> > No. The generation of the mask in sysfs is not done by > >> >> > executing the code in acpi_nfit_ctl. One of the reasons I call > >> >> > function 0 to test changes I am making to the ioctl path itself. > >> >> > The sysfs has nothing to do with that path and cannot be used > >> >> > to serve this purpose. > >> >> > > >> >> > And since the content of sysfs has been edited it also can not be > >> >> > used as a basic test of firmware. > >> >> > > >> >> > What is the downside to allowing the calling of function 0? > >> >> > >> >> It needlessly expands the kernel ABI. I would suggest, if you want to > >> > > >> > No. It is not needless. It is not an ABI extension. > >> > Same goes for the override feature. > >> > >> If the need is testing then we have a tools/testing/nvdimm for that. > > > > > > > >> Of course it's an ABI extension, it allows userspace to discover DSM > >> function numbers the kernel didn't know about at compile time. > > > > > > A modification to a library or kernel that changes the results of a > > function (or system call) doesn't necessarily break (or extend) an ABI. > > An obvious example is that of a random number generator function. > > A library/kernel is completely free to change the implementation > > of the random number generator (and the values it returns) > > without breaking the ABI provided all other rules of ABI preservation > > are followed. > > > > Now lets look at problem at hand. The pass thru mechanism has very > > little semantic overhead. Fill in the nd_cmd_pkg as described in ndctl.h, > > call the ioctl w/ argument with ND_CMD_CALL, and the kernel will marshal > > up the arguments, call the DSM and return the results. The values > > of nd_command could be any value and it is for the DSM to either accept > > or reject the input argument. I wrote this interface and this is how > > I defined it. > > > > The user application is not changing irrespective of if the kernel applies > > a mask to the passed in nd_command argument. The data structures are not > > changing at either source level or binary level. The calling convention is not > > changing. No object file changes are required. Nothing related to ABI > > preservation is impacted. The only question is whether the application > > of a mask to special case function 0 breaks/extends the ABI. > > > > It turns out that this point doesn't really matter as your position > > is invalid either way. > > > > The argument for this not being an API breakage/extension: > > > > A DSM could either implement or not a function index for any value of N. > > So, a correctly written application must take into account that for > > any value of N, the DSM may return error or not. Preserving an ABI > > doesn't require the library/kernel preserve incorrect application > > behavior. > > > > Now, assume that the special casing of function zero does constitute > > a breakage/extension of the ABI: > > > > I'm not the one wishing to special case function 0, you are. > > So, to this point I say, Dan please don't make needless extension to > > the ABI. Its and extension and you've provided no valid reason > > for making it. > > > > Your argument to disallow function zero is invalid. > > > > There is nothing harmful per se to allow function 0. All DSMs that return > > non zero are required to have it. By excluding it, you actually create the > > impression that the underlying DSM is violating the DSM specification. > > This goes back to the original reasoning for pushing back on the > override for the leaf-level _DSM methods. Specifically the ability to > bypass the standardization process to ship vendor-specific behavior. You're conflating the two contested patches. Allowing function 0 and allowing the override. While similar in most respects, function index 0 and function index != 0, there is a key difference, function 0 is defined by ACPI for all DSMs. So, there can be no bypassing of standardization process with function 0 as it is already defined. As for the addition of new DSM functions in the future, remember that the DSM is governed by a guid that is defined in the ACPI spec. While it is technically true that any one who writes firmware could create firmware that hijacks the DSM interface to add new functions not currently defined it would be foolish for them to do so as they risk collisions with updates from the ACPI forum. (They could also modify already defined and allowed by linux functions. But again, foolish.) > Now, the other side of the argument is that if the next spec adds new > _DSMs a simple override can enable them. I am more sympathetic to the > override for the leaf / DIMM level because those _DSMs truly are > DIMM-vendor specific, but the root device is not. Also, none of the > root-level DSMs added for 6.2 are in any way critical for proper > operation of the platform, and I do not see any bus-level > functionality on the horizon that we need to aggressively pre-enable. > It was a mistake to use _DSM for common root-level functionality, and > we shouldn't double down on that mistake by allowing unfettered As to the moral aspects of ACPI's decision to standardiz the DSM for NVDIMM, I take no position on whether it was a good thing or a bad thing; but it is a thing. We need to handle it. I see no particular benefit to making our own lives more difficult. > definition of new interfaces. NVDIMM is not so special that it needs > to bypass the standard ACPI-to-kernel development pipeline.
On Wed, Jul 5, 2017 at 4:14 PM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote: > On Wed, Jul 05, 2017 at 09:35:48AM -0700, Dan Williams wrote: [..] >> It was a mistake to use _DSM for common root-level functionality, and >> we shouldn't double down on that mistake by allowing unfettered > > As to the moral aspects of ACPI's decision to standardiz the DSM for NVDIMM, > I take no position on whether it was a good thing or a bad thing; but it > is a thing. We need to handle it. I see no particular benefit to > making our own lives more difficult. We do handle everything we need to. Making future updates move at the same pace as standard ACPI enabing is the goal as well as not adding any momentum to continue abusing _DSM when we should be creating named methods for bus-level generic functionality. As a maintainer of this subsystem I'm fine with the burden of continuing to touch the code as the specification evolves and that stance matches standard Linux practice.
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index b46fca2..5e4c137 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -253,6 +253,8 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm, cmd_name = nvdimm_bus_cmd_name(cmd); cmd_mask = nd_desc->cmd_mask; dsm_mask = cmd_mask; + if (cmd == ND_CMD_CALL) + dsm_mask = nd_desc->bus_dsm_mask; desc = nd_cmd_bus_desc(cmd); uuid = to_nfit_uuid(NFIT_DEV_BUS); handle = adev->handle; @@ -1613,6 +1615,7 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) struct nvdimm_bus_descriptor *nd_desc = &acpi_desc->nd_desc; const u8 *uuid = to_nfit_uuid(NFIT_DEV_BUS); struct acpi_device *adev; + unsigned long dsm_mask; int i; nd_desc->cmd_mask = acpi_desc->bus_cmd_force_en; @@ -1624,6 +1627,11 @@ static void acpi_nfit_init_dsms(struct acpi_nfit_desc *acpi_desc) if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) set_bit(i, &nd_desc->cmd_mask); set_bit(ND_CMD_CALL, &nd_desc->cmd_mask); + + dsm_mask = 0x3bf; + for_each_set_bit(i, &dsm_mask, BITS_PER_LONG) + if (acpi_check_dsm(adev->handle, uuid, 1, 1ULL << i)) + set_bit(i, &nd_desc->bus_dsm_mask); } static ssize_t range_index_show(struct device *dev, diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h index 6c80701..f8b8f43 100644 --- a/include/linux/libnvdimm.h +++ b/include/linux/libnvdimm.h @@ -54,6 +54,7 @@ typedef int (*ndctl_fn)(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm_bus_descriptor { const struct attribute_group **attr_groups; + unsigned long bus_dsm_mask; unsigned long cmd_mask; struct module *module; char *provider_name;
Add a bus level dsm_mask to nvdimm_bus_descriptor to allow the passthru calling mechanism to specify a different mask from the cmd_mask. Populate bus_dsm_mask and use it to filter dsm calls that user can make through the pass thru interface. Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com> --- drivers/acpi/nfit/core.c | 8 ++++++++ include/linux/libnvdimm.h | 1 + 2 files changed, 9 insertions(+)