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Re: [PATCH 0/5] ARM virt: Add NVDIMM support
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From: |
Igor Mammedov |
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Subject: |
Re: [PATCH 0/5] ARM virt: Add NVDIMM support |
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Date: |
Mon, 25 Nov 2019 16:45:41 +0100 |
On Mon, 25 Nov 2019 13:20:02 +0000
Shameerali Kolothum Thodi <address@hidden> wrote:
> Hi Eric/Igor,
>
> > -----Original Message-----
> > From: Shameerali Kolothum Thodi
> > Sent: 22 October 2019 15:05
> > To: 'Auger Eric' <address@hidden>; address@hidden;
> > address@hidden; address@hidden
> > Cc: address@hidden; address@hidden; xuwei (O)
> > <address@hidden>; address@hidden; Linuxarm
> > <address@hidden>
> > Subject: RE: [PATCH 0/5] ARM virt: Add NVDIMM support
not related to problem discussed in this patch but you probably
need to update docs/specs/acpi_nvdimm.txt to account for your changes
> >
>
> [..]
>
> > > one question: I noticed that when a NVDIMM slot is hotplugged one get
> > > the following trace on guest:
> > >
> > > nfit ACPI0012:00: found a zero length table '0' parsing nfit
> > > pmem0: detected capacity change from 0 to 1073741824
> > >
> > > Have you experienced the 0 length trace?
> >
> > I double checked and yes that trace is there. And I did a quick check with
> > x86 and it is not there.
> >
> > The reason looks like, ARM64 kernel receives an additional 8 bytes size when
> > the kernel evaluates the "_FIT" object.
> >
> > For the same test scenario, Qemu reports a FIT buffer size of 0xb8 and
> >
> > X86 Guest kernel,
> > [ 1.601077] acpi_nfit_init: data 0xffff8a273dc12b18 sz 0xb8
> >
> > ARM64 Guest,
> > [ 0.933133] acpi_nfit_init: data 0xffff00003cbe6018 sz 0xc0
> >
> > I am not sure how that size gets changed for ARM which results in
> > the above mentioned 0 length trace. I need to debug this further.
> >
> > Please let me know if you have any pointers...
>
> I spend some time debugging this further and it looks like the AML code
> behaves differently on x86 and ARM64.
FIT table is built dynamically and you are the first to debug
such issue.
(apart from the author the NVDIMM code.
btw: why NVDIMM author is not on CC list???)
> Booted guest with nvdimm mem, and used SSDT override with dbg prints
> added,
>
> -object memory-backend-ram,id=mem1,size=1G \
> -device nvdimm,id=dimm1,memdev=mem1 \
>
> On X86,
> -----------
>
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: Read FIT: offset 0 FIT size 0xb8 Dirty
> Yes.
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: read_fit_out buf size 0xc0
> func_ret_status 0
>
> [AML]"NVDIMM-NCAL: Rcvd RLEN 000000C0"
> [AML]"NVDIMM-NCAL: Creating OBUF with 000005E0 bits"
> [AML]"NVDIMM-NCAL: Created BUF(Local7) size 000000BC"
> [AML]"NVDIMM-RFIT Rcvd buf size 000000BC"
> [AML]"NVDIMM-RFIT Created NVDR.RFIT.BUFF size 000000B8"
> [AML]"NVDIMM-FIT: Rcvd buf size 000000B8"
>
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: Read FIT: offset 0xb8 FIT size 0xb8
> Dirty No.
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: read_fit_out buf size 0x8
> func_ret_status 0
>
> [AML]"NVDIMM-NCAL: Rcvd RLEN 00000008"
> [AML]"NVDIMM-NCAL: Creating OBUF with 00000020 bits"
> [AML]"NVDIMM-NCAL: Created BUF(Local7) size 00000004"
> [AML]"NVDIMM-RFIT Rcvd buf size 00000004"
> [AML]"NVDIMM-FIT: Rcvd buf size 00000000"
> [AML]"NVDIMM-FIT: _FIT returned size 000000B8"
>
> [ KERNEL] acpi_nfit_init: NVDIMM: data 0xffff9855bb9a7518 sz 0xb8 --> Guest
> receives correct size(0xb8) here
>
> On ARM64,
> ---------------
>
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: Read FIT: offset 0 FIT size 0xb8 Dirty
> Yes.
> [Qemu]VDIMM:nvdimm_dsm_func_read_fit: read_fit_out buf size 0xc0
> func_ret_status 0
>
> [AML]"NVDIMM-NCAL: Rcvd RLEN 00000000000000C0"
> [AML]"NVDIMM-NCAL: Creating OBUF with 00000000000005E0 bits"
> [AML]"NVDIMM-NCAL: Created BUF(Local7) size 00000000000000BC"
> [AML]"NVDIMM-RFIT Rcvd buf size 00000000000000BC"
> [AML]"NVDIMM-RFIT Created NVDR.RFIT.BUFF size 00000000000000B8"
> [AML]"NVDIMM-FIT: Rcvd buf size 00000000000000B8"
>
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: Read FIT: offset 0xb8 FIT size 0xb8
> Dirty No.
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: read_fit_out buf size 0x8
> func_ret_status 0
>
> [AML]"NVDIMM-NCAL: Rcvd RLEN 0000000000000008"
> [AML]"NVDIMM-NCAL: Creating OBUF with 0000000000000020 bits" --> All looks
> same as x86 up to here.
> [AML]"NVDIMM-NCAL: Created BUF(Local7) size 0000000000000008" ---> The size
> goes wrong. 8 bytes instead of 4!.
> [AML]"NVDIMM-RFIT Rcvd buf size 0000000000000008"
> [AML]"NVDIMM-RFIT Created NVDR.RFIT.BUFF size 0000000000000004"
> [AML]"NVDIMM-FIT: Rcvd buf size 0000000000000008" --> Again size goes wrong.
> 8 bytes instead of 4!.
Local1 = SizeOf (Local0)
printf("NVDIMM-RFIT Rcvd buf size %o", Local1)
Local1 -= 0x04
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ here you get -4 so sizes you see are
consistent
If ((Local1 == Zero))
{
Return (Buffer (Zero){})
}
CreateField (Local0, 0x20, (Local1 << 0x03), BUFF)
printf("NVDIMM-RFIT Created NVDR.RFIT.BUFF size %o", Local1)
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: Read FIT: offset 0xc0 FIT size 0xb8
> Dirty No. -->Another read is attempted
> [Qemu]NVDIMM:nvdimm_dsm_func_read_fit: read_fit_out buf size 0x8
> func_ret_status 3 --> Error status returned
status 3 means that QEMU didn't like content of NRAM, and there is only
1 place like this in nvdimm_dsm_func_read_fit()
if (read_fit->offset > fit->len) {
func_ret_status = NVDIMM_DSM_RET_STATUS_INVALID;
goto exit;
}
so I'd start looking from here and check that QEMU gets expected data
in nvdimm_dsm_write(). In other words I'd try to trace/compare
content of DSM buffer (from qemu side).
> [AML]"NVDIMM-NCAL: Rcvd RLEN 0000000000000008"
> [AML]"NVDIMM-NCAL: Creating OBUF with 0000000000000020 bits"
> [AML]"NVDIMM-NCAL: Created BUF(Local7) size 0000000000000008"
> [AML]"NVDIMM-FIT: Rcvd buf size 0000000000000000"
RFIT returns 0-sized buffer in case of error
> [AML]"NVDIMM-FIT: _FIT returned size 00000000000000C0" --> Wrong size
> returned.
after that it goes
Local0 = Buffer (Zero){}
Local0 = RFIT (Local3)
Local1 = SizeOf (Local0)
printf("NVDIMM-FIT: Rcvd buf size %o", Local1)
If ((RSTA == 0x0100))
{
Local2 = Buffer (Zero){}
Local3 = Zero
}
Else
{
If ((Local1 == Zero))
--> here, probably on the second iteration of the loop taking Zero
size as EOF sign but without checking for any error (RSTA !=0)
and returning partial buffer only
{
printf("NVDIMM-FIT: _FIT returned size %o",
SizeOf(Local2))
Return (Local2)
}
relevant code in QEMU that builds this AML is in nvdimm_build_fit()
> [ KERNEL] acpi_nfit_init: NVDIMM: data 0xffff0000fc57ce18 sz 0xc0 -->Kernel
> gets 0xc0 instead of 0xb8
>
>
> It looks like the aml, "CreateField (ODAT, Zero, Local1, OBUF)" goes wrong for
> ARM64 when the buffer is all zeroes. My knowledge on aml is very limited and
> not
> sure this is a 32/64bit issue or not. I am attaching the SSDT files with the
> above
> dbg prints added. Could you please take a look and let me know what actually
> is
> going on here...
diff -u SSDT-dbg-x86.dsl SSDT-dbg-arm64.dsl
--- SSDT-dbg-x86.dsl 2019-11-25 14:50:22.024983026 +0100
+++ SSDT-dbg-arm64.dsl 2019-11-25 14:50:06.740690645 +0100
@@[...]
@@ -28,7 +28,7 @@
Method (NCAL, 5, Serialized)
{
Local6 = MEMA /* \MEMA */
- OperationRegion (NPIO, SystemIO, 0x0A18, 0x04)
+ OperationRegion (NPIO, SystemMemory, 0x09090000, 0x04)
that's fine and matches your code
OperationRegion (NRAM, SystemMemory, Local6, 0x1000)
Field (NPIO, DWordAcc, NoLock, Preserve)
{
@@ -210,6 +210,6 @@
}
}
- Name (MEMA, 0xBFBFD000)
+ Name (MEMA, 0xFFFF0000)
However value here is suspicious. If I recall right it should
point to DMS buffer allocated by firmware somewhere in the guest RAM.
}
> Much appreciated,
> Shameer.
>
>