Thanks Andrew. + More CPU people in our team. Do you want to post your patch there for reference? :-)
BTW: Would you please share how to trigger such case at your side? Did you report above 4GB memory to be tested? As such all drivers are loaded to above 4GB? Do you also allocate BIN to above 4GB? Thank you Yao Jiewen > -----Original Message----- > From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of > Andrew Fish via edk2-devel > Sent: Monday, March 11, 2019 11:59 PM > To: Yao, Jiewen <jiewen....@intel.com> > Cc: edk2-devel <edk2-devel@lists.01.org>; Laszlo Ersek <ler...@redhat.com> > Subject: Re: [edk2] UefiCpuPkg CpuDxe GDT init question? > > Jiewen, > > These three fixes got me past the CpuDxe driver: > https://bugzilla.tianocore.org/show_bug.cgi?id=1613 > > Now I getting page faults loading SMM.... > > Thanks, > > Andrew Fish > > > On Mar 8, 2019, at 7:10 PM, Andrew Fish <af...@apple.com> wrote: > > > > > > > >> On Mar 8, 2019, at 7:08 AM, Laszlo Ersek <ler...@redhat.com > <mailto:ler...@redhat.com>> wrote: > >> > >> On 03/08/19 15:13, Yao, Jiewen wrote: > >>> I guess the historic reason is that AP and BSP share same GDT before. As > such, the GDT need to be below 4G, to let AP switch from real mode to > protected mode. > >>> We don't get issue, because Runtime memory is in BIN, and most > platform allocates BIN under 4G. > >>> > >>> Some thought: > >>> 1) I am think we not sure if AP is using same GDT as BSP today. If yes, we > need GDT under 4G, by using MaxAddress. If no, there should be no > restriction for BSP GDT. The (UINT32) case should be removed for BSP. But > we still AP GDT below 4G, to support wake from INIT-SIPI-SIPI. > > > > Jiewen, > > > > It looks like there are several places that assume memory is < 4 GB in the > CpuDxe driver. > > > > I noticed SetCodeSelector () is using a far jump to change the CS at that is > limited < 4 GB. I had to hack around it via: > > popq %rax > > pushq %rcx > > pushq %rax > > lretq > > > > There is some other crash later on. > > > > > >>> 2) I am not sure why we need runtime memory. Do we need touch GDT > at UEFI runtime? > >> > >> I could be confusing things *very badly*, but I vaguely remember that > >> APs could be woken up spuriously later, and they must be able to execute > >> code "enough" to go back to sleep. > >> > >> The following commits look relevant: > >> > >> - 7615702169b8 ("UefiCpuPkg/MpInitLib: Add AsmRelocateApLoop() > assembly > >> code", 2016-08-17) > >> > >> - 4d3314f69488 ("UefiCpuPkg/MpInitLib: Place APs in safe loop before > >> hand-off to OS", 2016-08-17) > >> > >> - bf2786dc7900 ("UefiCpuPkg/DxeMpLib: Allocate new safe stack < 4GB", > >> 2016-11-28) > >> > > > > If I'm remembering correctly there are optional idle states for the AP. I > think the real mode hlt loop might have used too much power on an UP OS. > > > > It is also not clear to me that we don't need the GDT when in real mode. In > big-real mode you go to protected mode set the GDT and then it can get > used for big-real so it seems like the GDT is in play even in real mode. > > > > Thanks, > > > > Andrew Fish > > > > > >> Laszlo > >> > >>> > >>> > >>> > >>> Thank you > >>> Yao Jiewen > >>> > >>> > >>>> -----Original Message----- > >>>> From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org > <mailto:edk2-devel-boun...@lists.01.org>] On Behalf Of > >>>> Laszlo Ersek > >>>> Sent: Friday, March 8, 2019 12:00 AM > >>>> To: Andrew Fish <af...@apple.com <mailto:af...@apple.com>>; > edk2-devel <edk2-devel@lists.01.org <mailto:edk2-devel@lists.01.org>> > >>>> Subject: Re: [edk2] UefiCpuPkg CpuDxe GDT init question? > >>>> > >>>> Hi Andrew, > >>>> > >>>> On 03/07/19 23:37, Andrew Fish via edk2-devel wrote: > >>>>> I'm trying to understand why gdtPtr.Base is casting to (UINT32)? > >>>>> 1) gdtPtr.Base is a a UINTN > >>>>> 2) It is legal for AllocateRuntimePool() to return an address > 4GB > >>>>> > >>>>> It seems like the code should just cast to (UINTN)? > >>>>> > >>>>> > >>>>> > >>>> > https://github.com/tianocore/edk2/blob/master/UefiCpuPkg/CpuDxe/CpuG > <https://github.com/tianocore/edk2/blob/master/UefiCpuPkg/CpuDxe/Cpu > G> > >>>> dt.c#L151 > >>>> > >>>> I think you are right. > >>>> > >>>> I'm missing the background on this too. I tried to see if any > >>>> justification was given in a git commit message, but according to "git > >>>> blame", this code dates back to the original addition of the driver, > >>>> namely commit a47463f28382 ("Add CPU DXE driver for IA32 & X64 > >>>> processor > >>>> architectures.", 2009-05-27). The commit message is unhelpful (for > 3119 > >>>> lines added). > >>>> > >>>> Thanks > >>>> Laszlo > >>>> > >>>>> > >>>>> > >>>>> > >>>>> VOID > >>>>> InitGlobalDescriptorTable ( > >>>>> VOID > >>>>> ) > >>>>> { > >>>>> GDT_ENTRIES *gdt; > >>>>> IA32_DESCRIPTOR gdtPtr; > >>>>> > >>>>> // > >>>>> // Allocate Runtime Data for the GDT > >>>>> // > >>>>> gdt = AllocateRuntimePool (sizeof (GdtTemplate) + 8); > >>>>> ASSERT (gdt != NULL); > >>>>> gdt = ALIGN_POINTER (gdt, 8); > >>>>> > >>>>> // > >>>>> // Initialize all GDT entries > >>>>> // > >>>>> CopyMem (gdt, &GdtTemplate, sizeof (GdtTemplate)); > >>>>> > >>>>> // > >>>>> // Write GDT register > >>>>> // > >>>>> gdtPtr.Base = (UINT32)(UINTN)(VOID*) gdt; > >>>>> gdtPtr.Limit = (UINT16) (sizeof (GdtTemplate) - 1); > >>>>> AsmWriteGdtr (&gdtPtr); > >>>>> > >>>>> Thanks, > >>>>> > >>>>> Andrew Fish > >>>>> _______________________________________________ > >>>>> edk2-devel mailing list > >>>>> edk2-devel@lists.01.org > >>>>> https://lists.01.org/mailman/listinfo/edk2-devel > >>>>> > >>>> > >>>> _______________________________________________ > >>>> edk2-devel mailing list > >>>> edk2-devel@lists.01.org > >>>> https://lists.01.org/mailman/listinfo/edk2-devel > > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
