Re: [PATCH v2 2/3] hw/cxl: Add QTG _DSM support for ACPI0017 device

[Jonathan Cameron]

On Tue, 12 Sep 2023 21:12:45 +0000
Fan Ni <fan.ni@samsung.com> wrote:

> On Mon, Sep 04, 2023 at 05:18:46PM +0100, Jonathan Cameron wrote:
> 
> > From: Dave Jiang <dave.jiang@intel.com>
> > 
> > Add a simple _DSM call support for the ACPI0017 device to return a fake QTG
> > ID value of 0 in all cases. The enabling is for _DSM plumbing testing
> > from the OS.
> > 
> > Following edited for readbility only
> > 
> > Device (CXLM)
> > {
> >     Name (_HID, "ACPI0017")  // _HID: Hardware ID
> > ...
> >     Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
> >     {
> >         If ((Arg0 == ToUUID ("f365f9a6-a7de-4071-a66a-b40c0b4f8e52")))
> >         {
> >             If ((Arg2 == Zero))
> >             {
> >                 Return (Buffer (One) { 0x01 })
> >             }
> > 
> >             If ((Arg2 == One))
> >             {
> >                 Return (Package (0x02)
> >                 {
> >                     Buffer (0x02)
> >                     { 0x01, 0x00 },
> >                     Package (0x01)
> >                     {
> >                         Buffer (0x02)
> >                         { 0x00, 0x00 }
> >                     }
> >                 })
> >             }
> >         }
> >     }
> > 
> > Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>  
> 
> Looks good to me. One minor comment inline.
> > 
> > --
> > v2: Minor edit to drop reference to switches in patch description.
> > ---
> >  include/hw/acpi/cxl.h |  1 +
> >  hw/acpi/cxl.c         | 57 +++++++++++++++++++++++++++++++++++++++++++
> >  hw/i386/acpi-build.c  |  1 +
> >  3 files changed, 59 insertions(+)
> > 
> > diff --git a/include/hw/acpi/cxl.h b/include/hw/acpi/cxl.h
> > index acf4418886..8f22c71530 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
> > diff --git a/hw/acpi/cxl.c b/hw/acpi/cxl.c
> > index 92b46bc932..5e9039785a 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)  
> 
> Not a concern for now, I think, do we need to check the revision
> field?

Any new versions should be defined to be backwards compatible...
So hopefully not (though it has gone wrong a few times in the
past when spec reviewers like me haven't been paying attention :(
If that happens we'll have to deal with it when it becomes public.

Jonathan

> 
> Fan
> > +{
> > +    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, PXBCXLDev *cxl)
> >  {
> >      PXBDev *pxb = PXB_DEV(cxl);
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index bb12b0ad43..d3bc5875eb 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1422,6 +1422,7 @@ 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);
> > -- 
> > 2.39.2
> > 
> >