Re: Problems in PV dom0 on recent x86 hardware

[Jürgen Groß <jgross@xxxxxxxx>]

On 09.07.24 15:08, Jason Andryuk wrote:
> On 2024-07-09 06:56, Jürgen Groß wrote:
> > On 09.07.24 09:01, Jan Beulich wrote:
> > > On 09.07.2024 08:36, Jürgen Groß wrote:
> > > > On 09.07.24 08:24, Jan Beulich wrote:
> > > > > On 08.07.2024 23:30, Jason Andryuk wrote:
> > > > > >    From the backtrace, it looks like the immediate case is just trying to
> > > > > > read a 4-byte version:
> > > > > >
> > > > > >    >>>> [   44.575541]  ucsi_acpi_dsm+0x53/0x80
> > > > > >    >>>> [   44.575546]  ucsi_acpi_read+0x2e/0x60
> > > > > >    >>>> [   44.575550]  ucsi_register+0x24/0xa0
> > > > > >    >>>> [   44.575555]  ucsi_acpi_probe+0x162/0x1e3
> > > > > >
> > > > > > int ucsi_register(struct ucsi *ucsi)
> > > > > > {
> > > > > >            int ret;
> > > > > >
> > > > > >            ret = ucsi->ops->read(ucsi, UCSI_VERSION, &ucsi->version,
> > > > > >                                  sizeof(ucsi->version));
> > > > > >
> > > > > > ->read being ucsi_acpi_read()
> > > > > >
> > > > > > However, the driver also appears write to adjacent addresses.
> > > > > There are also corresponding write functions in the driver, yes, but
> > > > > ucsi_acpi_async_write() (used directly or indirectly) similarly calls
> > > > > ucsi_acpi_dsm(), which wires through to acpi_evaluate_dsm(). That's
> > > > > ACPI object evaluation, which isn't obvious without seeing the
> > > > > involved AML whether it might write said memory region.
> > > > I guess an ACPI dump would help here?
> > > Perhaps, yes.
> > It is available in the bug report:
> >
> > https://bugzilla.opensuse.org/show_bug.cgi?id=1227301
> After acpixtract & iasl:
>
> $ grep -ir FEEC *
> dsdt.dsl:   OperationRegion (ECMM, SystemMemory, 0xFEEC2000, 0x0100)
> ssdt16.dsl: OperationRegion (SUSC, SystemMemory, 0xFEEC2100, 0x30)
>
>
> from the DSDT:
>      Scope (\_SB.PCI0.LPC0.EC0)
>      {
>          OperationRegion (ECMM, SystemMemory, 0xFEEC2000, 0x0100)
>          Field (ECMM, AnyAcc, Lock, Preserve)
>          {
>              TWBT,   2048
>          }
>
>          Name (BTBF, Buffer (0x0100)
>          {
>               0x00                                             // .
>          })
>          Method (BTIF, 0, NotSerialized)
>          {
>              BTBF = TWBT /* \_SB_.PCI0.LPC0.EC0_.TWBT */
>              Return (BTBF) /* \_SB_.PCI0.LPC0.EC0_.BTBF */
>          }
>      }
>
>  From SSDT16:
> DefinitionBlock ("", "SSDT", 2, "LENOVO", "UsbCTabl", 0x00000001)
> {
>      External (_SB_.PCI0.LPC0.EC0_, DeviceObj)
>
>      Scope (\_SB)
>      {
>          OperationRegion (SUSC, SystemMemory, 0xFEEC2100, 0x30)
>          Field (SUSC, ByteAcc, Lock, Preserve)
>          {
>
>
> This embedded controller (?) seems to live at 0xfeec2xxx.
What is the takeaway from that?

Is this a firmware bug (if yes, pointers to a specification saying that
this is an illegal configuration would be nice), or do we need a way to
map this page from dom0?


Juergen