Re: [edk2-devel] [edk2-libc Patch v3 1/1] ek2-libc: wrmsr function available in edk2module is not working as expected

["Michael D Kinney" <michael.d.kinney@intel.com>]

Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>

> -----Original Message-----
> From: Jayaprakash, N <n.jayaprakash@intel.com>
> Sent: Friday, April 19, 2024 2:01 AM
> To: devel@edk2.groups.io
> Cc: Jayaprakash, N <n.jayaprakash@intel.com>; Rebecca Cran
> <rebecca@bsdio.com>; Kinney, Michael D <michael.d.kinney@intel.com>
> Subject: [edk2-libc Patch v3 1/1] ek2-libc: wrmsr function available
> in edk2module is not working as expected
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4745
> 
> This commit fixes the issue reported in the BZ4745.
> The wrmsr was always writing 0 to the higher 32 bits of the msr
> register.
> This was due to a logical flaw in the code, where the input variable
> of
> type unsigned int was left shitted by 32 bits without explicitly
> converting it to a 64 bit value.
> 
> The issue is with the below statement.
> data = vedx << 32 | veax;
> Where the vedx which is an unsigned int, after left shifting by 32
> bits
> its value will be set to 0. Because of this the higher 32 bits of the
> MSR
> are always set to 0. This has been fixed by this commit.
> 
> Cc: Rebecca Cran <rebecca@bsdio.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Jayaprakash N <n.jayaprakash@intel.com>
> Signed-off-by: Jayaprakash N <n.jayaprakash@intel.com>
> ---
>  .../Python/Python-3.6.8/PyMod-3.6.8/Modules/edk2module.c        | 2
> +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/AppPkg/Applications/Python/Python-3.6.8/PyMod-
> 3.6.8/Modules/edk2module.c b/AppPkg/Applications/Python/Python-
> 3.6.8/PyMod-3.6.8/Modules/edk2module.c
> index d6af8da..f688b51 100644
> --- a/AppPkg/Applications/Python/Python-3.6.8/PyMod-
> 3.6.8/Modules/edk2module.c
> +++ b/AppPkg/Applications/Python/Python-3.6.8/PyMod-
> 3.6.8/Modules/edk2module.c
> @@ -3886,7 +3886,7 @@ edk2_wrmsr(PyObject *self, PyObject *args)
>    UINT64       data = 0;
>    if (!PyArg_ParseTuple(args, "III", &vecx, &veax, &vedx))
>      return NULL;
> -  data = vedx << 32 | veax;
> +  data = LShiftU64(vedx, 32) | veax;
>    Py_BEGIN_ALLOW_THREADS
>    AsmWriteMsr64(vecx, data);
>    Py_END_ALLOW_THREADS
> --
> 2.44.0.windows.1



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