[PATCH] libnvdimm, btt: BTT updates for UEFI 2.7 format

[PATCH] libnvdimm, btt: BTT updates for UEFI 2.7 format

[Vishal Verma]

The UEFI 2.7 specification defines an updated BTT metadata format,
bumping the revision to 2.0. Add support for the new format, while
retaining compatibility for the old 1.1 format.

New BTTs will be created using the newest (2.0 as of this writing)
format.

Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Linda Knippers <linda.knippers@hpe.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
 drivers/nvdimm/btt.c      | 28 ++++++++++++++++++++--------
 drivers/nvdimm/btt.h      |  7 +++++++
 drivers/nvdimm/btt_devs.c | 44 +++++++++++++++++++++++++++++++++++++++-----
 drivers/nvdimm/nd.h       |  1 +
 4 files changed, 67 insertions(+), 13 deletions(-)

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 983718b..629c376 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -37,8 +37,8 @@ static int arena_read_bytes(struct arena_info *arena, resource_size_t offset,
 	struct nd_btt *nd_btt = arena->nd_btt;
 	struct nd_namespace_common *ndns = nd_btt->ndns;
 
-	/* arena offsets are 4K from the base of the device */
-	offset += SZ_4K;
+	/* arena offsets may be shifted from the base of the device */
+	offset += arena->nd_btt->initial_offset;
 	return nvdimm_read_bytes(ndns, offset, buf, n, flags);
 }
 
@@ -48,8 +48,8 @@ static int arena_write_bytes(struct arena_info *arena, resource_size_t offset,
 	struct nd_btt *nd_btt = arena->nd_btt;
 	struct nd_namespace_common *ndns = nd_btt->ndns;
 
-	/* arena offsets are 4K from the base of the device */
-	offset += SZ_4K;
+	/* arena offsets may be shifted from the base of the device */
+	offset += arena->nd_btt->initial_offset;
 	return nvdimm_write_bytes(ndns, offset, buf, n, flags);
 }
 
@@ -576,8 +576,10 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
 	arena->internal_lbasize = roundup(arena->external_lbasize,
 					INT_LBASIZE_ALIGNMENT);
 	arena->nfree = BTT_DEFAULT_NFREE;
-	arena->version_major = 1;
-	arena->version_minor = 1;
+
+	/* New BTTs will always be v2.0 */
+	arena->version_major = 2;
+	arena->version_minor = 0;
 
 	if (available % BTT_PG_SIZE)
 		available -= (available % BTT_PG_SIZE);
@@ -1425,18 +1427,28 @@ int nvdimm_namespace_attach_btt(struct nd_namespace_common *ndns)
 {
 	struct nd_btt *nd_btt = to_nd_btt(ndns->claim);
 	struct nd_region *nd_region;
+	struct btt_sb *btt_sb;
 	struct btt *btt;
 	size_t rawsize;
+	int btt_ver;
 
 	if (!nd_btt->uuid || !nd_btt->ndns || !nd_btt->lbasize) {
 		dev_dbg(&nd_btt->dev, "incomplete btt configuration\n");
 		return -ENODEV;
 	}
 
-	rawsize = nvdimm_namespace_capacity(ndns) - SZ_4K;
+	btt_sb = devm_kzalloc(&nd_btt->dev, sizeof(*btt_sb), GFP_KERNEL);
+	btt_ver = nd_btt_version(nd_btt, ndns, btt_sb);
+	if (btt_ver < 0) {
+		dev_err(&nd_btt->dev, "%s: set initial_offset = 0\n", __func__);
+		nd_btt->initial_offset = 0;
+	}
+
+	rawsize = nvdimm_namespace_capacity(ndns) - nd_btt->initial_offset;
 	if (rawsize < ARENA_MIN_SIZE) {
 		dev_dbg(&nd_btt->dev, "%s must be at least %ld bytes\n",
-				dev_name(&ndns->dev), ARENA_MIN_SIZE + SZ_4K);
+				dev_name(&ndns->dev),
+				ARENA_MIN_SIZE + nd_btt->initial_offset);
 		return -ENXIO;
 	}
 	nd_region = to_nd_region(nd_btt->dev.parent);
diff --git a/drivers/nvdimm/btt.h b/drivers/nvdimm/btt.h
index b2f8651..1845df2 100644
--- a/drivers/nvdimm/btt.h
+++ b/drivers/nvdimm/btt.h
@@ -44,6 +44,11 @@ enum btt_init_state {
 	INIT_READY
 };
 
+enum btt_versions {
+	ND_BTT_1_1 = 1,
+	ND_BTT_2_0
+};
+
 struct log_entry {
 	__le32 lba;
 	__le32 old_map;
@@ -184,5 +189,7 @@ struct btt {
 };
 
 bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super);
+int nd_btt_version(struct nd_btt *nd_btt, struct nd_namespace_common *ndns,
+		struct btt_sb *btt_sb);
 
 #endif
diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index 31d875a..22e148a 100644
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -260,20 +260,54 @@ bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super)
 }
 EXPORT_SYMBOL(nd_btt_arena_is_valid);
 
+int nd_btt_version(struct nd_btt *nd_btt, struct nd_namespace_common *ndns,
+		struct btt_sb *btt_sb)
+{
+	/*
+	 * At this point, the claim class can only be 'BTT' or 'NONE'. BTT
+	 * implies a BTT v2.0 and none implies v1.1
+	 */
+	if (ndns->claim_class == NVDIMM_CCLASS_BTT) {
+		/* Probe for BTT v2.0 */
+		if (nvdimm_read_bytes(ndns, 0, btt_sb, sizeof(*btt_sb), 0))
+			return -ENXIO;
+		if (!nd_btt_arena_is_valid(nd_btt, btt_sb))
+			return -ENODEV;
+		if ((le16_to_cpu(btt_sb->version_major) == 2) &&
+				(le16_to_cpu(btt_sb->version_minor) == 0)) {
+			nd_btt->initial_offset = 0;
+			return ND_BTT_2_0;
+		}
+	} else {
+		/* Probe for BTT v1.1 */
+		if (nvdimm_read_bytes(ndns, SZ_4K, btt_sb, sizeof(*btt_sb), 0))
+			return -ENXIO;
+		if (!nd_btt_arena_is_valid(nd_btt, btt_sb))
+			return -ENODEV;
+		if ((le16_to_cpu(btt_sb->version_major) == 1) &&
+				(le16_to_cpu(btt_sb->version_minor) == 1)) {
+			nd_btt->initial_offset = SZ_4K;
+			return ND_BTT_1_1;
+		}
+	}
+	return -ENXIO;
+}
+EXPORT_SYMBOL(nd_btt_version);
+
 static int __nd_btt_probe(struct nd_btt *nd_btt,
 		struct nd_namespace_common *ndns, struct btt_sb *btt_sb)
 {
+	int btt_ver;
+
 	if (!btt_sb || !ndns || !nd_btt)
 		return -ENODEV;
 
-	if (nvdimm_read_bytes(ndns, SZ_4K, btt_sb, sizeof(*btt_sb), 0))
-		return -ENXIO;
-
 	if (nvdimm_namespace_capacity(ndns) < SZ_16M)
 		return -ENXIO;
 
-	if (!nd_btt_arena_is_valid(nd_btt, btt_sb))
-		return -ENODEV;
+	btt_ver = nd_btt_version(nd_btt, ndns, btt_sb);
+	if (btt_ver < 0)
+		return btt_ver;
 
 	nd_btt->lbasize = le32_to_cpu(btt_sb->external_lbasize);
 	nd_btt->uuid = kmemdup(btt_sb->uuid, 16, GFP_KERNEL);
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index 8cabd83..474ad8a 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -194,6 +194,7 @@ struct nd_btt {
 	u64 size;
 	u8 *uuid;
 	int id;
+	int initial_offset;
 };
 
 enum nd_pfn_mode {
-- 
2.9.3

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Re: [PATCH] libnvdimm, btt: BTT updates for UEFI 2.7 format

[Dan Williams]

On Fri, Jun 23, 2017 at 7:17 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
> The UEFI 2.7 specification defines an updated BTT metadata format,
> bumping the revision to 2.0. Add support for the new format, while
> retaining compatibility for the old 1.1 format.
>
> New BTTs will be created using the newest (2.0 as of this writing)
> format.
>
> Cc: Toshi Kani <toshi.kani@hpe.com>
> Cc: Linda Knippers <linda.knippers@hpe.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>  drivers/nvdimm/btt.c      | 28 ++++++++++++++++++++--------
>  drivers/nvdimm/btt.h      |  7 +++++++
>  drivers/nvdimm/btt_devs.c | 44 +++++++++++++++++++++++++++++++++++++++-----
>  drivers/nvdimm/nd.h       |  1 +
>  4 files changed, 67 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index 983718b..629c376 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
[..]
> @@ -576,8 +576,10 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
>         arena->internal_lbasize = roundup(arena->external_lbasize,
>                                         INT_LBASIZE_ALIGNMENT);
>         arena->nfree = BTT_DEFAULT_NFREE;
> -       arena->version_major = 1;
> -       arena->version_minor = 1;
> +
> +       /* New BTTs will always be v2.0 */
> +       arena->version_major = 2;
> +       arena->version_minor = 0;

I don't think this is correct. The v2.0 format is generally more
dangerous than v1.1 because its info block can coexist with other
nvdimm info-blocks and fs-super-blocks. So we should always default to
v1.1 unless explicitly forced into v2.0 mode with the claim-class /
address-abstraction-guid set in the v1.2 namespace label. Without that
indicator to tie break ambiguous situations we can't use the v2.0
format which is strictly for inter-OS / UEFI compatibility.
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Re: [PATCH] libnvdimm, btt: BTT updates for UEFI 2.7 format

[Vishal Verma]

On 06/25, Dan Williams wrote:
> On Fri, Jun 23, 2017 at 7:17 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
> > The UEFI 2.7 specification defines an updated BTT metadata format,
> > bumping the revision to 2.0. Add support for the new format, while
> > retaining compatibility for the old 1.1 format.
> >
> > New BTTs will be created using the newest (2.0 as of this writing)
> > format.
> >
> > Cc: Toshi Kani <toshi.kani@hpe.com>
> > Cc: Linda Knippers <linda.knippers@hpe.com>
> > Cc: Dan Williams <dan.j.williams@intel.com>
> > Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> > ---
> >  drivers/nvdimm/btt.c      | 28 ++++++++++++++++++++--------
> >  drivers/nvdimm/btt.h      |  7 +++++++
> >  drivers/nvdimm/btt_devs.c | 44 +++++++++++++++++++++++++++++++++++++++-----
> >  drivers/nvdimm/nd.h       |  1 +
> >  4 files changed, 67 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> > index 983718b..629c376 100644
> > --- a/drivers/nvdimm/btt.c
> > +++ b/drivers/nvdimm/btt.c
> [..]
> > @@ -576,8 +576,10 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
> >         arena->internal_lbasize = roundup(arena->external_lbasize,
> >                                         INT_LBASIZE_ALIGNMENT);
> >         arena->nfree = BTT_DEFAULT_NFREE;
> > -       arena->version_major = 1;
> > -       arena->version_minor = 1;
> > +
> > +       /* New BTTs will always be v2.0 */
> > +       arena->version_major = 2;
> > +       arena->version_minor = 0;
> 
> I don't think this is correct. The v2.0 format is generally more
> dangerous than v1.1 because its info block can coexist with other
> nvdimm info-blocks and fs-super-blocks. So we should always default to
> v1.1 unless explicitly forced into v2.0 mode with the claim-class /
> address-abstraction-guid set in the v1.2 namespace label. Without that
> indicator to tie break ambiguous situations we can't use the v2.0
> format which is strictly for inter-OS / UEFI compatibility.

Hm, I tend to agree, but in that case, shouldn't the holder class for
BTTs automatically default to BTT instead of NONE, i.e. add the address
abstraction guid by default, thus creating v2 BTTs. I feel it might come
as more of a surprise if we continue to create v1.1 BTTs by default when
the spec states 2.0..
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Re: [PATCH] libnvdimm, btt: BTT updates for UEFI 2.7 format

[Dan Williams]

On Mon, Jun 26, 2017 at 12:31 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
> On 06/25, Dan Williams wrote:
>> On Fri, Jun 23, 2017 at 7:17 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
>> > The UEFI 2.7 specification defines an updated BTT metadata format,
>> > bumping the revision to 2.0. Add support for the new format, while
>> > retaining compatibility for the old 1.1 format.
>> >
>> > New BTTs will be created using the newest (2.0 as of this writing)
>> > format.
>> >
>> > Cc: Toshi Kani <toshi.kani@hpe.com>
>> > Cc: Linda Knippers <linda.knippers@hpe.com>
>> > Cc: Dan Williams <dan.j.williams@intel.com>
>> > Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
>> > ---
>> >  drivers/nvdimm/btt.c      | 28 ++++++++++++++++++++--------
>> >  drivers/nvdimm/btt.h      |  7 +++++++
>> >  drivers/nvdimm/btt_devs.c | 44 +++++++++++++++++++++++++++++++++++++++-----
>> >  drivers/nvdimm/nd.h       |  1 +
>> >  4 files changed, 67 insertions(+), 13 deletions(-)
>> >
>> > diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
>> > index 983718b..629c376 100644
>> > --- a/drivers/nvdimm/btt.c
>> > +++ b/drivers/nvdimm/btt.c
>> [..]
>> > @@ -576,8 +576,10 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
>> >         arena->internal_lbasize = roundup(arena->external_lbasize,
>> >                                         INT_LBASIZE_ALIGNMENT);
>> >         arena->nfree = BTT_DEFAULT_NFREE;
>> > -       arena->version_major = 1;
>> > -       arena->version_minor = 1;
>> > +
>> > +       /* New BTTs will always be v2.0 */
>> > +       arena->version_major = 2;
>> > +       arena->version_minor = 0;
>>
>> I don't think this is correct. The v2.0 format is generally more
>> dangerous than v1.1 because its info block can coexist with other
>> nvdimm info-blocks and fs-super-blocks. So we should always default to
>> v1.1 unless explicitly forced into v2.0 mode with the claim-class /
>> address-abstraction-guid set in the v1.2 namespace label. Without that
>> indicator to tie break ambiguous situations we can't use the v2.0
>> format which is strictly for inter-OS / UEFI compatibility.
>
> Hm, I tend to agree, but in that case, shouldn't the holder class for
> BTTs automatically default to BTT instead of NONE, i.e. add the address
> abstraction guid by default, thus creating v2 BTTs. I feel it might come
> as more of a surprise if we continue to create v1.1 BTTs by default when
> the spec states 2.0..

That default is up to userspace. If an environment wants to use BTT v2
it needs to use updated tooling that sets the holder class. The kernel
default should remain as 'none' because it can't tell if BTT v2 or v1
is intended even when using v1.2 namespaces. The spec pretends that we
haven't been shipping this support in the Linux kernel for years, so I
think it's more important to be backwards compatible by default.
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Re: [PATCH] libnvdimm, btt: BTT updates for UEFI 2.7 format

[Vishal Verma]

On 06/26, Dan Williams wrote:
> On Mon, Jun 26, 2017 at 12:31 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
> > On 06/25, Dan Williams wrote:
> >> On Fri, Jun 23, 2017 at 7:17 PM, Vishal Verma <vishal.l.verma@intel.com> wrote:
> >> > The UEFI 2.7 specification defines an updated BTT metadata format,
> >> > bumping the revision to 2.0. Add support for the new format, while
> >> > retaining compatibility for the old 1.1 format.
> >> >
> >> > New BTTs will be created using the newest (2.0 as of this writing)
> >> > format.
> >> >
> >> > Cc: Toshi Kani <toshi.kani@hpe.com>
> >> > Cc: Linda Knippers <linda.knippers@hpe.com>
> >> > Cc: Dan Williams <dan.j.williams@intel.com>
> >> > Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> >> > ---
> >> >  drivers/nvdimm/btt.c      | 28 ++++++++++++++++++++--------
> >> >  drivers/nvdimm/btt.h      |  7 +++++++
> >> >  drivers/nvdimm/btt_devs.c | 44 +++++++++++++++++++++++++++++++++++++++-----
> >> >  drivers/nvdimm/nd.h       |  1 +
> >> >  4 files changed, 67 insertions(+), 13 deletions(-)
> >> >
> >> > diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> >> > index 983718b..629c376 100644
> >> > --- a/drivers/nvdimm/btt.c
> >> > +++ b/drivers/nvdimm/btt.c
> >> [..]
> >> > @@ -576,8 +576,10 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size,
> >> >         arena->internal_lbasize = roundup(arena->external_lbasize,
> >> >                                         INT_LBASIZE_ALIGNMENT);
> >> >         arena->nfree = BTT_DEFAULT_NFREE;
> >> > -       arena->version_major = 1;
> >> > -       arena->version_minor = 1;
> >> > +
> >> > +       /* New BTTs will always be v2.0 */
> >> > +       arena->version_major = 2;
> >> > +       arena->version_minor = 0;
> >>
> >> I don't think this is correct. The v2.0 format is generally more
> >> dangerous than v1.1 because its info block can coexist with other
> >> nvdimm info-blocks and fs-super-blocks. So we should always default to
> >> v1.1 unless explicitly forced into v2.0 mode with the claim-class /
> >> address-abstraction-guid set in the v1.2 namespace label. Without that
> >> indicator to tie break ambiguous situations we can't use the v2.0
> >> format which is strictly for inter-OS / UEFI compatibility.
> >
> > Hm, I tend to agree, but in that case, shouldn't the holder class for
> > BTTs automatically default to BTT instead of NONE, i.e. add the address
> > abstraction guid by default, thus creating v2 BTTs. I feel it might come
> > as more of a surprise if we continue to create v1.1 BTTs by default when
> > the spec states 2.0..
> 
> That default is up to userspace. If an environment wants to use BTT v2
> it needs to use updated tooling that sets the holder class. The kernel
> default should remain as 'none' because it can't tell if BTT v2 or v1
> is intended even when using v1.2 namespaces. The spec pretends that we
> haven't been shipping this support in the Linux kernel for years, so I
> think it's more important to be backwards compatible by default.

Sounds good, mechanism, not policy :)
I'll send out a v2 with these updates.
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