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Re: Problems in PV dom0 on recent x86 hardware


  • To: Jürgen Groß <jgross@xxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
  • From: Jason Andryuk <jason.andryuk@xxxxxxx>
  • Date: Tue, 9 Jul 2024 09:08:11 -0400
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Tue, 09 Jul 2024 13:08:29 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

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.

Regards,
Jason



 


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