diff mbox series

[v2,2/7] hw/acpi/nvdimm: Fix for NVDIMM incorrect DSM output buffer length

Message ID 20200117174522.22044-3-shameerali.kolothum.thodi@huawei.com (mailing list archive)
State New, archived
Headers show
Series ARM virt: Add NVDIMM support | expand

Commit Message

Shameerali Kolothum Thodi Jan. 17, 2020, 5:45 p.m. UTC
As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
the Buffer Field <= to the size of an Integer (in bits), it will
be treated as an integer. Moreover, the integer size depends on
DSDT tables revision number. If revision number is < 2, integer
size is 32 bits, otherwise it is 64 bits. Current NVDIMM common
DSM aml code (NCAL) uses CreateField() for creating DSM output
buffer. This creates an issue in arm/virt platform where DSDT
revision number is 2 and results in DSM buffer with a wrong
size(8 bytes) gets returned when actual length is < 8 bytes.
This causes guest kernel to report,

"nfit ACPI0012:00: found a zero length table '0' parsing nfit"

In order to fix this, aml code is now modified such that it builds
the DSM output buffer in a byte by byte fashion when length is
smaller than Integer size.

Suggested-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
---
Please find the previous discussion on this here,
https://patchwork.kernel.org/cover/11174959/

---
 hw/acpi/nvdimm.c                            | 36 +++++++++++++++++++--
 tests/qtest/bios-tables-test-allowed-diff.h |  2 ++
 2 files changed, 35 insertions(+), 3 deletions(-)

Comments

Eric Auger Jan. 28, 2020, 5:08 p.m. UTC | #1
Hi Shameer,
On 1/17/20 6:45 PM, Shameer Kolothum wrote:
> As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> the Buffer Field <= to the size of an Integer (in bits), it will
> be treated as an integer. Moreover, the integer size depends on
> DSDT tables revision number. If revision number is < 2, integer
> size is 32 bits, otherwise it is 64 bits. Current NVDIMM common
> DSM aml code (NCAL) uses CreateField() for creating DSM output
> buffer. This creates an issue in arm/virt platform where DSDT
> revision number is 2 and results in DSM buffer with a wrong
> size(8 bytes) gets returned when actual length is < 8 bytes.
> This causes guest kernel to report,
> 
> "nfit ACPI0012:00: found a zero length table '0' parsing nfit"
> 
> In order to fix this, aml code is now modified such that it builds
> the DSM output buffer in a byte by byte fashion when length is
> smaller than Integer size.
> 
> Suggested-by: Igor Mammedov <imammedo@redhat.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> Please find the previous discussion on this here,
> https://patchwork.kernel.org/cover/11174959/
> 
> ---
>  hw/acpi/nvdimm.c                            | 36 +++++++++++++++++++--
>  tests/qtest/bios-tables-test-allowed-diff.h |  2 ++
>  2 files changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 9fdad6dc3f..5e7b8318d0 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -964,6 +964,7 @@ static void nvdimm_build_common_dsm(Aml *dev)
>      Aml *method, *ifctx, *function, *handle, *uuid, *dsm_mem, *elsectx2;
>      Aml *elsectx, *unsupport, *unpatched, *expected_uuid, *uuid_invalid;
>      Aml *pckg, *pckg_index, *pckg_buf, *field, *dsm_out_buf, *dsm_out_buf_size;
> +    Aml *whilectx, *offset;
>      uint8_t byte_list[1];
>  
>      method = aml_method(NVDIMM_COMMON_DSM, 5, AML_SERIALIZED);
> @@ -1117,13 +1118,42 @@ static void nvdimm_build_common_dsm(Aml *dev)
>      /* RLEN is not included in the payload returned to guest. */
>      aml_append(method, aml_subtract(aml_name(NVDIMM_DSM_OUT_BUF_SIZE),
>                 aml_int(4), dsm_out_buf_size));
> +
> +    /*
> +     * As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> +     * the Buffer Field <= to the size of an Integer (in bits), it will
> +     * be treated as an integer. Moreover, the integer size depends on
> +     * DSDT tables revision number. If revision number is < 2, integer
> +     * size is 32 bits, otherwise it is 64 bits.
> +     * Because of this CreateField() canot be used if RLEN < Integer Size.
nit: Because of this, CreateField() cannot

Thanks

Eric
> +     * Hence build dsm_out_buf byte by byte.
> +     */
> +    ifctx = aml_if(aml_lless(dsm_out_buf_size, aml_sizeof(aml_int(0))));
> +    offset = aml_local(2);
> +    aml_append(ifctx, aml_store(aml_int(0), offset));
> +    aml_append(ifctx, aml_name_decl("TBUF", aml_buffer(1, NULL)));
> +    aml_append(ifctx, aml_store(aml_buffer(0, NULL), dsm_out_buf));
> +
> +    whilectx = aml_while(aml_lless(offset, dsm_out_buf_size));
> +    /* Copy 1 byte at offset from ODAT to temporary buffer(TBUF). */
> +    aml_append(whilectx, aml_store(aml_derefof(aml_index(
> +                                   aml_name(NVDIMM_DSM_OUT_BUF), offset)),
> +                                   aml_index(aml_name("TBUF"), aml_int(0))));
> +    aml_append(whilectx, aml_concatenate(dsm_out_buf, aml_name("TBUF"),
> +                                         dsm_out_buf));
> +    aml_append(whilectx, aml_increment(offset));
> +    aml_append(ifctx, whilectx);
> +
> +    aml_append(ifctx, aml_return(dsm_out_buf));
> +    aml_append(method, ifctx);
> +
> +    /* If RLEN >= Integer size, just use CreateField() operator */
>      aml_append(method, aml_store(aml_shiftleft(dsm_out_buf_size, aml_int(3)),
>                                   dsm_out_buf_size));
>      aml_append(method, aml_create_field(aml_name(NVDIMM_DSM_OUT_BUF),
>                 aml_int(0), dsm_out_buf_size, "OBUF"));
> -    aml_append(method, aml_concatenate(aml_buffer(0, NULL), aml_name("OBUF"),
> -                                       dsm_out_buf));
> -    aml_append(method, aml_return(dsm_out_buf));
> +    aml_append(method, aml_return(aml_name("OBUF")));
> +
>      aml_append(dev, method);
>  }
>  
> diff --git a/tests/qtest/bios-tables-test-allowed-diff.h b/tests/qtest/bios-tables-test-allowed-diff.h
> index dfb8523c8b..eb8bae1407 100644
> --- a/tests/qtest/bios-tables-test-allowed-diff.h
> +++ b/tests/qtest/bios-tables-test-allowed-diff.h
> @@ -1 +1,3 @@
>  /* List of comma-separated changed AML files to ignore */
> +"tests/data/acpi/pc/SSDT.dimmpxm",
> +"tests/data/acpi/q35/SSDT.dimmpxm",
>
Igor Mammedov Feb. 6, 2020, 4:06 p.m. UTC | #2
On Fri, 17 Jan 2020 17:45:17 +0000
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:

> As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> the Buffer Field <= to the size of an Integer (in bits), it will
> be treated as an integer. Moreover, the integer size depends on
> DSDT tables revision number. If revision number is < 2, integer
> size is 32 bits, otherwise it is 64 bits. Current NVDIMM common
> DSM aml code (NCAL) uses CreateField() for creating DSM output
> buffer. This creates an issue in arm/virt platform where DSDT
> revision number is 2 and results in DSM buffer with a wrong
> size(8 bytes) gets returned when actual length is < 8 bytes.
> This causes guest kernel to report,
> 
> "nfit ACPI0012:00: found a zero length table '0' parsing nfit"
> 
> In order to fix this, aml code is now modified such that it builds
> the DSM output buffer in a byte by byte fashion when length is
> smaller than Integer size.
> 
> Suggested-by: Igor Mammedov <imammedo@redhat.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> Please find the previous discussion on this here,
> https://patchwork.kernel.org/cover/11174959/
> 
> ---
>  hw/acpi/nvdimm.c                            | 36 +++++++++++++++++++--
>  tests/qtest/bios-tables-test-allowed-diff.h |  2 ++
>  2 files changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 9fdad6dc3f..5e7b8318d0 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -964,6 +964,7 @@ static void nvdimm_build_common_dsm(Aml *dev)
>      Aml *method, *ifctx, *function, *handle, *uuid, *dsm_mem, *elsectx2;
>      Aml *elsectx, *unsupport, *unpatched, *expected_uuid, *uuid_invalid;
>      Aml *pckg, *pckg_index, *pckg_buf, *field, *dsm_out_buf, *dsm_out_buf_size;
> +    Aml *whilectx, *offset;
>      uint8_t byte_list[1];
>  
>      method = aml_method(NVDIMM_COMMON_DSM, 5, AML_SERIALIZED);
> @@ -1117,13 +1118,42 @@ static void nvdimm_build_common_dsm(Aml *dev)
>      /* RLEN is not included in the payload returned to guest. */
>      aml_append(method, aml_subtract(aml_name(NVDIMM_DSM_OUT_BUF_SIZE),
>                 aml_int(4), dsm_out_buf_size));
> +
> +    /*
> +     * As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> +     * the Buffer Field <= to the size of an Integer (in bits), it will
> +     * be treated as an integer. Moreover, the integer size depends on
> +     * DSDT tables revision number. If revision number is < 2, integer
> +     * size is 32 bits, otherwise it is 64 bits.
> +     * Because of this CreateField() canot be used if RLEN < Integer Size.
> +     * Hence build dsm_out_buf byte by byte.
> +     */
> +    ifctx = aml_if(aml_lless(dsm_out_buf_size, aml_sizeof(aml_int(0))));

this decomplies into

 If (Local1 < SizeOf ())

which doesn't look right

> +    offset = aml_local(2);
> +    aml_append(ifctx, aml_store(aml_int(0), offset));
> +    aml_append(ifctx, aml_name_decl("TBUF", aml_buffer(1, NULL)));
> +    aml_append(ifctx, aml_store(aml_buffer(0, NULL), dsm_out_buf));
> +
> +    whilectx = aml_while(aml_lless(offset, dsm_out_buf_size));
> +    /* Copy 1 byte at offset from ODAT to temporary buffer(TBUF). */
> +    aml_append(whilectx, aml_store(aml_derefof(aml_index(
> +                                   aml_name(NVDIMM_DSM_OUT_BUF), offset)),
> +                                   aml_index(aml_name("TBUF"), aml_int(0))));
> +    aml_append(whilectx, aml_concatenate(dsm_out_buf, aml_name("TBUF"),
> +                                         dsm_out_buf));
> +    aml_append(whilectx, aml_increment(offset));
> +    aml_append(ifctx, whilectx);
> +
> +    aml_append(ifctx, aml_return(dsm_out_buf));
> +    aml_append(method, ifctx);
> +
> +    /* If RLEN >= Integer size, just use CreateField() operator */
>      aml_append(method, aml_store(aml_shiftleft(dsm_out_buf_size, aml_int(3)),
>                                   dsm_out_buf_size));
>      aml_append(method, aml_create_field(aml_name(NVDIMM_DSM_OUT_BUF),
>                 aml_int(0), dsm_out_buf_size, "OBUF"));
> -    aml_append(method, aml_concatenate(aml_buffer(0, NULL), aml_name("OBUF"),
> -                                       dsm_out_buf));
> -    aml_append(method, aml_return(dsm_out_buf));
> +    aml_append(method, aml_return(aml_name("OBUF")));
> +
>      aml_append(dev, method);
>  }
>  
> diff --git a/tests/qtest/bios-tables-test-allowed-diff.h b/tests/qtest/bios-tables-test-allowed-diff.h
> index dfb8523c8b..eb8bae1407 100644
> --- a/tests/qtest/bios-tables-test-allowed-diff.h
> +++ b/tests/qtest/bios-tables-test-allowed-diff.h
> @@ -1 +1,3 @@
>  /* List of comma-separated changed AML files to ignore */
> +"tests/data/acpi/pc/SSDT.dimmpxm",
> +"tests/data/acpi/q35/SSDT.dimmpxm",
Shameerali Kolothum Thodi March 10, 2020, 11:22 a.m. UTC | #3
> -----Original Message-----
> From: Igor Mammedov [mailto:imammedo@redhat.com]
> Sent: 06 February 2020 16:06
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: qemu-devel@nongnu.org; qemu-arm@nongnu.org;
> eric.auger@redhat.com; peter.maydell@linaro.org;
> xiaoguangrong.eric@gmail.com; mst@redhat.com; Linuxarm
> <linuxarm@huawei.com>; xuwei (O) <xuwei5@huawei.com>;
> shannon.zhaosl@gmail.com; lersek@redhat.com
> Subject: Re: [PATCH v2 2/7] hw/acpi/nvdimm: Fix for NVDIMM incorrect DSM
> output buffer length
> 
> On Fri, 17 Jan 2020 17:45:17 +0000
> Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:
> 
> > As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if the
> > Buffer Field <= to the size of an Integer (in bits), it will be
> > treated as an integer. Moreover, the integer size depends on DSDT
> > tables revision number. If revision number is < 2, integer size is 32
> > bits, otherwise it is 64 bits. Current NVDIMM common DSM aml code
> > (NCAL) uses CreateField() for creating DSM output buffer. This creates
> > an issue in arm/virt platform where DSDT revision number is 2 and
> > results in DSM buffer with a wrong
> > size(8 bytes) gets returned when actual length is < 8 bytes.
> > This causes guest kernel to report,
> >
> > "nfit ACPI0012:00: found a zero length table '0' parsing nfit"
> >
> > In order to fix this, aml code is now modified such that it builds the
> > DSM output buffer in a byte by byte fashion when length is smaller
> > than Integer size.
> >
> > Suggested-by: Igor Mammedov <imammedo@redhat.com>
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > ---
> > Please find the previous discussion on this here,
> > https://patchwork.kernel.org/cover/11174959/
> >
> > ---
> >  hw/acpi/nvdimm.c                            | 36
> +++++++++++++++++++--
> >  tests/qtest/bios-tables-test-allowed-diff.h |  2 ++
> >  2 files changed, 35 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c index
> > 9fdad6dc3f..5e7b8318d0 100644
> > --- a/hw/acpi/nvdimm.c
> > +++ b/hw/acpi/nvdimm.c
> > @@ -964,6 +964,7 @@ static void nvdimm_build_common_dsm(Aml *dev)
> >      Aml *method, *ifctx, *function, *handle, *uuid, *dsm_mem,
> *elsectx2;
> >      Aml *elsectx, *unsupport, *unpatched, *expected_uuid, *uuid_invalid;
> >      Aml *pckg, *pckg_index, *pckg_buf, *field, *dsm_out_buf,
> > *dsm_out_buf_size;
> > +    Aml *whilectx, *offset;
> >      uint8_t byte_list[1];
> >
> >      method = aml_method(NVDIMM_COMMON_DSM, 5,
> AML_SERIALIZED); @@
> > -1117,13 +1118,42 @@ static void nvdimm_build_common_dsm(Aml *dev)
> >      /* RLEN is not included in the payload returned to guest. */
> >      aml_append(method,
> aml_subtract(aml_name(NVDIMM_DSM_OUT_BUF_SIZE),
> >                 aml_int(4), dsm_out_buf_size));
> > +
> > +    /*
> > +     * As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> > +     * the Buffer Field <= to the size of an Integer (in bits), it will
> > +     * be treated as an integer. Moreover, the integer size depends on
> > +     * DSDT tables revision number. If revision number is < 2, integer
> > +     * size is 32 bits, otherwise it is 64 bits.
> > +     * Because of this CreateField() canot be used if RLEN < Integer Size.
> > +     * Hence build dsm_out_buf byte by byte.
> > +     */
> > +    ifctx = aml_if(aml_lless(dsm_out_buf_size,
> > + aml_sizeof(aml_int(0))));
> 
> this decomplies into
> 
>  If (Local1 < SizeOf ())
> 
> which doesn't look right

Ok. I tried printing the value returned(SizeOf) and that looks alright.

Anyway, changed it into aml_int(1) which decompiles to

   If (Local1 < SizeOf (One))

Hope this is acceptable.

Thanks,
Shameer
Michael S. Tsirkin March 10, 2020, 11:36 a.m. UTC | #4
On Tue, Mar 10, 2020 at 11:22:05AM +0000, Shameerali Kolothum Thodi wrote:
> 
> 
> > -----Original Message-----
> > From: Igor Mammedov [mailto:imammedo@redhat.com]
> > Sent: 06 February 2020 16:06
> > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> > Cc: qemu-devel@nongnu.org; qemu-arm@nongnu.org;
> > eric.auger@redhat.com; peter.maydell@linaro.org;
> > xiaoguangrong.eric@gmail.com; mst@redhat.com; Linuxarm
> > <linuxarm@huawei.com>; xuwei (O) <xuwei5@huawei.com>;
> > shannon.zhaosl@gmail.com; lersek@redhat.com
> > Subject: Re: [PATCH v2 2/7] hw/acpi/nvdimm: Fix for NVDIMM incorrect DSM
> > output buffer length
> > 
> > On Fri, 17 Jan 2020 17:45:17 +0000
> > Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:
> > 
> > > As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if the
> > > Buffer Field <= to the size of an Integer (in bits), it will be
> > > treated as an integer. Moreover, the integer size depends on DSDT
> > > tables revision number. If revision number is < 2, integer size is 32
> > > bits, otherwise it is 64 bits. Current NVDIMM common DSM aml code
> > > (NCAL) uses CreateField() for creating DSM output buffer. This creates
> > > an issue in arm/virt platform where DSDT revision number is 2 and
> > > results in DSM buffer with a wrong
> > > size(8 bytes) gets returned when actual length is < 8 bytes.
> > > This causes guest kernel to report,
> > >
> > > "nfit ACPI0012:00: found a zero length table '0' parsing nfit"
> > >
> > > In order to fix this, aml code is now modified such that it builds the
> > > DSM output buffer in a byte by byte fashion when length is smaller
> > > than Integer size.
> > >
> > > Suggested-by: Igor Mammedov <imammedo@redhat.com>
> > > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > > ---
> > > Please find the previous discussion on this here,
> > > https://patchwork.kernel.org/cover/11174959/
> > >
> > > ---
> > >  hw/acpi/nvdimm.c                            | 36
> > +++++++++++++++++++--
> > >  tests/qtest/bios-tables-test-allowed-diff.h |  2 ++
> > >  2 files changed, 35 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c index
> > > 9fdad6dc3f..5e7b8318d0 100644
> > > --- a/hw/acpi/nvdimm.c
> > > +++ b/hw/acpi/nvdimm.c
> > > @@ -964,6 +964,7 @@ static void nvdimm_build_common_dsm(Aml *dev)
> > >      Aml *method, *ifctx, *function, *handle, *uuid, *dsm_mem,
> > *elsectx2;
> > >      Aml *elsectx, *unsupport, *unpatched, *expected_uuid, *uuid_invalid;
> > >      Aml *pckg, *pckg_index, *pckg_buf, *field, *dsm_out_buf,
> > > *dsm_out_buf_size;
> > > +    Aml *whilectx, *offset;
> > >      uint8_t byte_list[1];
> > >
> > >      method = aml_method(NVDIMM_COMMON_DSM, 5,
> > AML_SERIALIZED); @@
> > > -1117,13 +1118,42 @@ static void nvdimm_build_common_dsm(Aml *dev)
> > >      /* RLEN is not included in the payload returned to guest. */
> > >      aml_append(method,
> > aml_subtract(aml_name(NVDIMM_DSM_OUT_BUF_SIZE),
> > >                 aml_int(4), dsm_out_buf_size));
> > > +
> > > +    /*
> > > +     * As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> > > +     * the Buffer Field <= to the size of an Integer (in bits), it will
> > > +     * be treated as an integer. Moreover, the integer size depends on
> > > +     * DSDT tables revision number. If revision number is < 2, integer
> > > +     * size is 32 bits, otherwise it is 64 bits.
> > > +     * Because of this CreateField() canot be used if RLEN < Integer Size.
> > > +     * Hence build dsm_out_buf byte by byte.
> > > +     */
> > > +    ifctx = aml_if(aml_lless(dsm_out_buf_size,
> > > + aml_sizeof(aml_int(0))));
> > 
> > this decomplies into
> > 
> >  If (Local1 < SizeOf ())
> > 
> > which doesn't look right
> 
> Ok. I tried printing the value returned(SizeOf) and that looks alright.

Well it's illegal in ACPI, it's possible that OSPMs handle it the way
you want them to, but it's probably not a good idea to assume they will
always do.

The spec says:

DefSizeOf := SizeOfOp SuperName



> Anyway, changed it into aml_int(1) which decompiles to
> 
>    If (Local1 < SizeOf (One))
> 
> Hope this is acceptable.
> 
> Thanks,
> Shameer

I suspect it doesn't. And going into semantics, since they are set by
ASL:


19.6.125 SizeOf (Get Data Object Size)
Syntax
SizeOf (ObjectName) => Integer
Arguments
ObjectName must be a buffer, string or package object.
Description
Returns the size of a buffer, string, or package data object.
For a buffer, it returns the size in bytes of the data. For a string, it returns the size in bytes of the
string, not counting the trailing NULL. For a package, it returns the number of elements. For an
object reference, the size of the referenced object is returned. Other data types cause a fatal run-time
error.


Bottom line, I don't think you can figure out the integer size like this.
What's wrong with just assuming 8 byte integers? I guess sizes 5 to 8
will be slower with a 32 bit DSDT but why is that a problem?
Shameerali Kolothum Thodi March 10, 2020, 11:59 a.m. UTC | #5
> -----Original Message-----
> From: Qemu-devel
> [mailto:qemu-devel-bounces+shameerali.kolothum.thodi=huawei.com@nongn
> u.org] On Behalf Of Michael S. Tsirkin
> Sent: 10 March 2020 11:36
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: peter.maydell@linaro.org; xiaoguangrong.eric@gmail.com;
> shannon.zhaosl@gmail.com; qemu-devel@nongnu.org; Linuxarm
> <linuxarm@huawei.com>; eric.auger@redhat.com; qemu-arm@nongnu.org;
> xuwei (O) <xuwei5@huawei.com>; Igor Mammedov
> <imammedo@redhat.com>; lersek@redhat.com
> Subject: Re: [PATCH v2 2/7] hw/acpi/nvdimm: Fix for NVDIMM incorrect DSM
> output buffer length
> 
> On Tue, Mar 10, 2020 at 11:22:05AM +0000, Shameerali Kolothum Thodi
> wrote:
> >
> >
> > > -----Original Message-----
> > > From: Igor Mammedov [mailto:imammedo@redhat.com]
> > > Sent: 06 February 2020 16:06
> > > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> > > Cc: qemu-devel@nongnu.org; qemu-arm@nongnu.org;
> > > eric.auger@redhat.com; peter.maydell@linaro.org;
> > > xiaoguangrong.eric@gmail.com; mst@redhat.com; Linuxarm
> > > <linuxarm@huawei.com>; xuwei (O) <xuwei5@huawei.com>;
> > > shannon.zhaosl@gmail.com; lersek@redhat.com
> > > Subject: Re: [PATCH v2 2/7] hw/acpi/nvdimm: Fix for NVDIMM incorrect
> DSM
> > > output buffer length
> > >
> > > On Fri, 17 Jan 2020 17:45:17 +0000
> > > Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:
> > >
> > > > As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if the
> > > > Buffer Field <= to the size of an Integer (in bits), it will be
> > > > treated as an integer. Moreover, the integer size depends on DSDT
> > > > tables revision number. If revision number is < 2, integer size is 32
> > > > bits, otherwise it is 64 bits. Current NVDIMM common DSM aml code
> > > > (NCAL) uses CreateField() for creating DSM output buffer. This creates
> > > > an issue in arm/virt platform where DSDT revision number is 2 and
> > > > results in DSM buffer with a wrong
> > > > size(8 bytes) gets returned when actual length is < 8 bytes.
> > > > This causes guest kernel to report,
> > > >
> > > > "nfit ACPI0012:00: found a zero length table '0' parsing nfit"
> > > >
> > > > In order to fix this, aml code is now modified such that it builds the
> > > > DSM output buffer in a byte by byte fashion when length is smaller
> > > > than Integer size.
> > > >
> > > > Suggested-by: Igor Mammedov <imammedo@redhat.com>
> > > > Signed-off-by: Shameer Kolothum
> <shameerali.kolothum.thodi@huawei.com>
> > > > ---
> > > > Please find the previous discussion on this here,
> > > > https://patchwork.kernel.org/cover/11174959/
> > > >
> > > > ---
> > > >  hw/acpi/nvdimm.c                            | 36
> > > +++++++++++++++++++--
> > > >  tests/qtest/bios-tables-test-allowed-diff.h |  2 ++
> > > >  2 files changed, 35 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c index
> > > > 9fdad6dc3f..5e7b8318d0 100644
> > > > --- a/hw/acpi/nvdimm.c
> > > > +++ b/hw/acpi/nvdimm.c
> > > > @@ -964,6 +964,7 @@ static void nvdimm_build_common_dsm(Aml
> *dev)
> > > >      Aml *method, *ifctx, *function, *handle, *uuid, *dsm_mem,
> > > *elsectx2;
> > > >      Aml *elsectx, *unsupport, *unpatched, *expected_uuid,
> *uuid_invalid;
> > > >      Aml *pckg, *pckg_index, *pckg_buf, *field, *dsm_out_buf,
> > > > *dsm_out_buf_size;
> > > > +    Aml *whilectx, *offset;
> > > >      uint8_t byte_list[1];
> > > >
> > > >      method = aml_method(NVDIMM_COMMON_DSM, 5,
> > > AML_SERIALIZED); @@
> > > > -1117,13 +1118,42 @@ static void nvdimm_build_common_dsm(Aml
> *dev)
> > > >      /* RLEN is not included in the payload returned to guest. */
> > > >      aml_append(method,
> > > aml_subtract(aml_name(NVDIMM_DSM_OUT_BUF_SIZE),
> > > >                 aml_int(4), dsm_out_buf_size));
> > > > +
> > > > +    /*
> > > > +     * As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
> > > > +     * the Buffer Field <= to the size of an Integer (in bits), it will
> > > > +     * be treated as an integer. Moreover, the integer size depends on
> > > > +     * DSDT tables revision number. If revision number is < 2, integer
> > > > +     * size is 32 bits, otherwise it is 64 bits.
> > > > +     * Because of this CreateField() canot be used if RLEN < Integer
> Size.
> > > > +     * Hence build dsm_out_buf byte by byte.
> > > > +     */
> > > > +    ifctx = aml_if(aml_lless(dsm_out_buf_size,
> > > > + aml_sizeof(aml_int(0))));
> > >
> > > this decomplies into
> > >
> > >  If (Local1 < SizeOf ())
> > >
> > > which doesn't look right
> >
> > Ok. I tried printing the value returned(SizeOf) and that looks alright.
> 
> Well it's illegal in ACPI, it's possible that OSPMs handle it the way
> you want them to, but it's probably not a good idea to assume they will
> always do.
> 
> The spec says:
> 
> DefSizeOf := SizeOfOp SuperName
> 
> 
> 
> > Anyway, changed it into aml_int(1) which decompiles to
> >
> >    If (Local1 < SizeOf (One))
> >
> > Hope this is acceptable.
> >
> > Thanks,
> > Shameer
> 
> I suspect it doesn't. And going into semantics, since they are set by
> ASL:
> 
> 
> 19.6.125 SizeOf (Get Data Object Size)
> Syntax
> SizeOf (ObjectName) => Integer
> Arguments
> ObjectName must be a buffer, string or package object.
> Description
> Returns the size of a buffer, string, or package data object.
> For a buffer, it returns the size in bytes of the data. For a string, it returns the
> size in bytes of the
> string, not counting the trailing NULL. For a package, it returns the number of
> elements. For an
> object reference, the size of the referenced object is returned. Other data
> types cause a fatal run-time
> error.

Yes, I read that and was concerned. I did some experiments with SizeOf() with
different integer numbers and all were returning 8. But yes, it doesn't look like
the right approach.
 
> 
> Bottom line, I don't think you can figure out the integer size like this.
> What's wrong with just assuming 8 byte integers? I guess sizes 5 to 8
> will be slower with a 32 bit DSDT but why is that a problem?

Right. I guess that would work. I will add a comment to explain why we
are using 8.

Thanks,
Shameer

> MST
>
diff mbox series

Patch

diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
index 9fdad6dc3f..5e7b8318d0 100644
--- a/hw/acpi/nvdimm.c
+++ b/hw/acpi/nvdimm.c
@@ -964,6 +964,7 @@  static void nvdimm_build_common_dsm(Aml *dev)
     Aml *method, *ifctx, *function, *handle, *uuid, *dsm_mem, *elsectx2;
     Aml *elsectx, *unsupport, *unpatched, *expected_uuid, *uuid_invalid;
     Aml *pckg, *pckg_index, *pckg_buf, *field, *dsm_out_buf, *dsm_out_buf_size;
+    Aml *whilectx, *offset;
     uint8_t byte_list[1];
 
     method = aml_method(NVDIMM_COMMON_DSM, 5, AML_SERIALIZED);
@@ -1117,13 +1118,42 @@  static void nvdimm_build_common_dsm(Aml *dev)
     /* RLEN is not included in the payload returned to guest. */
     aml_append(method, aml_subtract(aml_name(NVDIMM_DSM_OUT_BUF_SIZE),
                aml_int(4), dsm_out_buf_size));
+
+    /*
+     * As per ACPI spec 6.3, Table 19-419 Object Conversion Rules, if
+     * the Buffer Field <= to the size of an Integer (in bits), it will
+     * be treated as an integer. Moreover, the integer size depends on
+     * DSDT tables revision number. If revision number is < 2, integer
+     * size is 32 bits, otherwise it is 64 bits.
+     * Because of this CreateField() canot be used if RLEN < Integer Size.
+     * Hence build dsm_out_buf byte by byte.
+     */
+    ifctx = aml_if(aml_lless(dsm_out_buf_size, aml_sizeof(aml_int(0))));
+    offset = aml_local(2);
+    aml_append(ifctx, aml_store(aml_int(0), offset));
+    aml_append(ifctx, aml_name_decl("TBUF", aml_buffer(1, NULL)));
+    aml_append(ifctx, aml_store(aml_buffer(0, NULL), dsm_out_buf));
+
+    whilectx = aml_while(aml_lless(offset, dsm_out_buf_size));
+    /* Copy 1 byte at offset from ODAT to temporary buffer(TBUF). */
+    aml_append(whilectx, aml_store(aml_derefof(aml_index(
+                                   aml_name(NVDIMM_DSM_OUT_BUF), offset)),
+                                   aml_index(aml_name("TBUF"), aml_int(0))));
+    aml_append(whilectx, aml_concatenate(dsm_out_buf, aml_name("TBUF"),
+                                         dsm_out_buf));
+    aml_append(whilectx, aml_increment(offset));
+    aml_append(ifctx, whilectx);
+
+    aml_append(ifctx, aml_return(dsm_out_buf));
+    aml_append(method, ifctx);
+
+    /* If RLEN >= Integer size, just use CreateField() operator */
     aml_append(method, aml_store(aml_shiftleft(dsm_out_buf_size, aml_int(3)),
                                  dsm_out_buf_size));
     aml_append(method, aml_create_field(aml_name(NVDIMM_DSM_OUT_BUF),
                aml_int(0), dsm_out_buf_size, "OBUF"));
-    aml_append(method, aml_concatenate(aml_buffer(0, NULL), aml_name("OBUF"),
-                                       dsm_out_buf));
-    aml_append(method, aml_return(dsm_out_buf));
+    aml_append(method, aml_return(aml_name("OBUF")));
+
     aml_append(dev, method);
 }
 
diff --git a/tests/qtest/bios-tables-test-allowed-diff.h b/tests/qtest/bios-tables-test-allowed-diff.h
index dfb8523c8b..eb8bae1407 100644
--- a/tests/qtest/bios-tables-test-allowed-diff.h
+++ b/tests/qtest/bios-tables-test-allowed-diff.h
@@ -1 +1,3 @@ 
 /* List of comma-separated changed AML files to ignore */
+"tests/data/acpi/pc/SSDT.dimmpxm",
+"tests/data/acpi/q35/SSDT.dimmpxm",