Re: [PATCH] hw/cxl: Add QTG _DSM support for ACPI0017 device

[Dave Jiang <dave.jiang@intel.com>]

On 1/26/23 11:24 AM, Jonathan Cameron wrote:
> On Thu, 26 Jan 2023 11:07:37 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
> Hi Dave,
> 
> That was quick!
> 
>> Add a simple _DSM call support for the ACPI0017 device to return a fake QTG
>> ID value. Given the current CXL implementation does not involve switches,
> 
> I don't follow.  What part doesn't involve switches?
> 
>> a faked value of 0 can be returned for the QTG ID. The enabling is for _DSM
>> plumbing testing from the OS.
> 
> Can you include a dump iasl -d for the DSDT chunk this generates. Much
> easier to review with that available.

         Device (CXLM)
         {
             Name (_HID, "ACPI0017")  // _HID: Hardware ID
             Method (_STA, 0, NotSerialized)  // _STA: Status
             {
                 Return (One)
             }

             Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
             {
                 If ((Arg0 == ToUUID 
("f365f9a6-a7de-4071-a66a-b40c0b4f8e52") /* Unknown UUID */))
                 {
                     If ((Arg2 == Zero))
                     {
                         Return (Buffer (One)
                         {
                              0x01 
       // .
                         })
                     }

                     If ((Arg2 == One))
                     {
                         Return (Package (0x02)
                         {
                             Buffer (0x02)
                             {
                                  0x01, 0x00 
           // ..
                             },

                             Package (0x01)
                             {
                                 Buffer (0x02)
                                 {
                                      0x00, 0x00 
               // ..
                                 }
                             }
                         })
                     }
                 }


> 
> On that note, tests need updating I think
> tests/qtest/bios-tables-test.c data which is in
> tests/data/acpi/q35/DSDT.cxl
> 
> We should update that test code as part of the volatile series as well
> as it's using the deprecated memdev parameter - not critical
> but never a good thing to leave old examples of what not to use in
> the tests.
> 
> Thanks,
> 
> Jonathan
> 
> p.s. I'm too lazy to look at the code without the AML to compare with
> as I'll review the AML first then look at if there are any oddities
> in the generation code.
> 
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   hw/acpi/cxl.c         |   57 +++++++++++++++++++++++++++++++++++++++++++++++++
>>   hw/i386/acpi-build.c  |    1 +
>>   include/hw/acpi/cxl.h |    1 +
>>   3 files changed, 59 insertions(+)
>>
>> diff --git a/hw/acpi/cxl.c b/hw/acpi/cxl.c
>> index 2bf8c0799359..cd6839c24416 100644
>> --- a/hw/acpi/cxl.c
>> +++ b/hw/acpi/cxl.c
>> @@ -30,6 +30,63 @@
>>   #include "qapi/error.h"
>>   #include "qemu/uuid.h"
>>   
>> +void build_cxl_dsm_method(Aml *dev)
>> +{
>> +    Aml *method, *ifctx, *ifctx2;
>> +
>> +    method = aml_method("_DSM", 4, AML_SERIALIZED);
>> +    {
>> +        Aml *function, *uuid;
>> +
>> +        uuid = aml_arg(0);
>> +        function = aml_arg(2);
>> +        /* CXL spec v3.0 9.17.3.1 *, QTG ID _DSM */
>> +        ifctx = aml_if(aml_equal(
>> +            uuid, aml_touuid("F365F9A6-A7DE-4071-A66A-B40C0B4F8E52")));
>> +
>> +        /* Function 0, standard DSM query function */
>> +        ifctx2 = aml_if(aml_equal(function, aml_int(0)));
>> +        {
>> +            uint8_t byte_list[1] = { 0x01 }; /* functions 1 only */
>> +
>> +            aml_append(ifctx2,
>> +                       aml_return(aml_buffer(sizeof(byte_list), byte_list)));
>> +        }
>> +        aml_append(ifctx, ifctx2);
>> +
>> +        /*
>> +         * Function 1
>> +         * A return value of {1, {0}} inciate that
>> +         * max supported QTG ID of 1 and recommended QTG is 0.
>> +         * The values here are faked to simplify emulation.
>> +         */
>> +        ifctx2 = aml_if(aml_equal(function, aml_int(1)));
>> +        {
>> +            uint16_t word_list[1] = { 0x01 };
>> +            uint16_t word_list2[1] = { 0 };
>> +            uint8_t *byte_list = (uint8_t *)word_list;
>> +            uint8_t *byte_list2 = (uint8_t *)word_list2;
>> +            Aml *pak, *pak1;
>> +
>> +            /*
>> +             * The return package is a package of a WORD and another package.
>> +             * The embedded package contains 0 or more WORDs for the
>> +             * recommended QTG IDs.
>> +             */
>> +            pak1 = aml_package(1);
>> +            aml_append(pak1, aml_buffer(sizeof(uint16_t), byte_list2));
>> +            pak = aml_package(2);
>> +            aml_append(pak, aml_buffer(sizeof(uint16_t), byte_list));
>> +            aml_append(pak, pak1);
>> +
>> +            aml_append(ifctx2, aml_return(pak));
>> +        }
>> +        aml_append(ifctx, ifctx2);
>> +    }
>> +    aml_append(method, ifctx);
>> +    aml_append(dev, method);
>> +}
>> +
>>   static void cedt_build_chbs(GArray *table_data, PXBDev *cxl)
>>   {
>>       SysBusDevice *sbd = SYS_BUS_DEVICE(cxl->cxl.cxl_host_bridge);
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index 285829802b1a..623f26a16db3 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -1313,6 +1313,7 @@ static void build_acpi0017(Aml *table)
>>       method = aml_method("_STA", 0, AML_NOTSERIALIZED);
>>       aml_append(method, aml_return(aml_int(0x01)));
>>       aml_append(dev, method);
>> +    build_cxl_dsm_method(dev);
>>   
>>       aml_append(scope, dev);
>>       aml_append(table, scope);
>> diff --git a/include/hw/acpi/cxl.h b/include/hw/acpi/cxl.h
>> index acf441888683..8f22c71530d8 100644
>> --- a/include/hw/acpi/cxl.h
>> +++ b/include/hw/acpi/cxl.h
>> @@ -25,5 +25,6 @@ void cxl_build_cedt(GArray *table_offsets, GArray *table_data,
>>                       BIOSLinker *linker, const char *oem_id,
>>                       const char *oem_table_id, CXLState *cxl_state);
>>   void build_cxl_osc_method(Aml *dev);
>> +void build_cxl_dsm_method(Aml *dev);
>>   
>>   #endif
>>
>>
>