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hw/acpi/nvdimm: Fix for NVDIMM incorrect DSM output buffer length

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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>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200421125934.14952-2-shameerali.kolothum.thodi@huawei.com>
Acked-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Shameer Kolothum 2020-04-21 13:59:28 +01:00 committed by Michael S. Tsirkin
parent e3a99063af
commit 71b0269ae9
2 changed files with 39 additions and 3 deletions
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40
hw/acpi/nvdimm.c
View File

@ -938,6 +938,7 @@ 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);
@ -1091,13 +1092,46 @@ 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.
*
* Also please note that APCI ASL operator SizeOf() doesn't support
* Integer and there isn't any other way to figure out the Integer
* size. Hence we assume 8 byte as Integer size and if RLEN < 8 bytes,
* build dsm_out_buf byte by byte.
*/
ifctx = aml_if(aml_lless(dsm_out_buf_size, aml_int(8)));
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);
}

2
tests/qtest/bios-tables-test-allowed-diff.h
View File

@ -1 +1,3 @@
/* List of comma-separated changed AML files to ignore */
"tests/data/acpi/pc/SSDT.dimmpxm",
"tests/data/acpi/q35/SSDT.dimmpxm",