The use of BitFieldOr64() is really only required when updating a portion of a 32-bit or 64-bit value that are not aligned on a 32-bit boundary and do not have a 32-bit aligned width. Since this use case is setting the lower 32-bits, simpler logic should be used.
data = LShiftU64(vedx, 32) | veax; Mike > -----Original Message----- > From: Jayaprakash, N <n.jayaprak...@intel.com> > Sent: Thursday, April 18, 2024 5:55 AM > To: devel@edk2.groups.io > Cc: Jayaprakash, N <n.jayaprak...@intel.com>; Rebecca Cran > <rebe...@bsdio.com>; Kinney, Michael D <michael.d.kin...@intel.com> > Subject: [edk2-libc Patch 2 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 <rebe...@bsdio.com> > Cc: Michael D Kinney <michael.d.kin...@intel.com> > Cc: Jayaprakash N <n.jayaprak...@intel.com> > Signed-off-by: Jayaprakash N <n.jayaprak...@intel.com> > --- > .../Python/Python-3.6.8/PyMod-3.6.8/Modules/edk2module.c | 3 > ++- > 1 file changed, 2 insertions(+), 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 8786df8..06bcf82 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 +3886,8 @@ 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); > + data = BitFieldOr64(data, 0, 31, veax); > Py_BEGIN_ALLOW_THREADS > AsmWriteMsr64(vecx, data); > Py_END_ALLOW_THREADS > -- > 2.44.0.windows.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#117999): https://edk2.groups.io/g/devel/message/117999 Mute This Topic: https://groups.io/mt/105597214/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
