Messages in this thread | | | Subject | Re: Boot regression with bacf6b499e11 ("x86/mm: Use a struct to reduce parameters for SME PGD mapping") on top of -rc8 | From | Laura Abbott <> | Date | Fri, 19 Jan 2018 23:03:27 -0800 |
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On 01/19/2018 10:57 PM, Laura Abbott wrote: > On 01/19/2018 10:15 PM, Tom Lendacky wrote: >> On 1/19/2018 11:25 PM, Gabriel C wrote: >>> 2018-01-20 5:02 GMT+01:00 Laura Abbott <labbott@redhat.com>: >>>> On 01/19/2018 06:23 PM, Gabriel C wrote: >>>>> >>>>> 2018-01-20 2:23 GMT+01:00 Laura Abbott <labbott@redhat.com>: >>>>>> >>>>>> Hi, >>>>> >>>>> >>>>> Hi , >>>>> >>>>>> >>>>>> Fedora got multiple reports of an early bootup crash post -rc8. >>>>>> Bisection showed bacf6b499e11 ("x86/mm: Use a struct to reduce >>>>>> parameters for SME PGD mapping") . It doesn't revert cleanly >>>>>> but if I revert the few other changes in arch/x86/mm/mem_encrypt.c >>>>>> as well it boots up fine. >>>>>> >>>>>> Annoyingly, I can't seem to get any actual kernel logs even with >>>>>> earlyprintk. It just reboots immediately (triple fault?). This >>>>>> happens on both of my Lenovo machines and I can ask other reporters >>>>>> for details as well. >>>>>> >>>>> >>>>> I tested these patches on 2 Lenovo Ideapad both with Skylake CPUs >>>>> on a older dual Xeon box , on 2 Toshibas with AMD APUs , on a RYZEN >>>>> box , >>>>> on dual EPYC box .. ofc on EPYC with mem_encrypt=on on the Intel CPUs >>>>> disabled. >>>>> >>>>> Also tested on top 4.14.13 , 4.14.14 as well on top 4.15.0-rc7 and on >>>>> current master/rc8++ without to see something like this. >>>>> >>>>> Also we pushed these patches on 4.14.13/14 and didn't got any reports >>>>> about >>>>> something like this. >>>>> >>>>> What Lenovo boxes are these ? maybe I find one to reproduce. >>>>> >>>>> >>>>>> $ git bisect log >>>>>> # bad: [ec835f8104a21f4d4eeb9d316ee71d2b4a7f00de] Merge tag >>>>>> 'trace-v4.15-rc4-3' of >>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace >>>>>> # good: [a8750ddca918032d6349adbf9a4b6555e7db20da] Linux 4.15-rc8 >>>>>> git bisect start 'origin/master' 'v4.15-rc8' >>>>>> # bad: [79683f80e4f07dba13cc08d0ebcf5c7b0aa1bf68] Merge tag >>>>>> 'mmc-v4.15-rc2-3' of >>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc >>>>>> git bisect bad 79683f80e4f07dba13cc08d0ebcf5c7b0aa1bf68 >>>>>> # good: [161f72ed6dbe7fb176585091d3b797125d310399] Merge tag >>>>>> 'mac80211-for-davem-2018-01-15' of >>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211 >>>>>> git bisect good 161f72ed6dbe7fb176585091d3b797125d310399 >>>>>> # good: [88dc7fca18001fd883e5ace775afa316b68c8f2c] Merge branch >>>>>> 'x86-pti-for-linus' of >>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip >>>>>> git bisect good 88dc7fca18001fd883e5ace775afa316b68c8f2c >>>>>> # bad: [d47924417319e3b6a728c0b690f183e75bc2a702] x86/intel_rdt/cqm: >>>>>> Prevent >>>>>> use after free >>>>>> git bisect bad d47924417319e3b6a728c0b690f183e75bc2a702 >>>>>> # good: [fc90ccfd286eabb05ec54521367df8663cf0bbbf] Revert "x86/apic: >>>>>> Remove >>>>>> init_bsp_APIC()" >>>>>> git bisect good fc90ccfd286eabb05ec54521367df8663cf0bbbf >>>>>> # bad: [bacf6b499e11760aef73a3bb5ce4e5eea74a3fd4] x86/mm: Use a >>>>>> struct to >>>>>> reduce parameters for SME PGD mapping >>>>>> git bisect bad bacf6b499e11760aef73a3bb5ce4e5eea74a3fd4 >>>>>> # good: [1303880179e67c59e801429b7e5d0f6b21137d99] x86/mm: Clean up >>>>>> register >>>>>> saving in the __enc_copy() assembly code >>>>>> git bisect good 1303880179e67c59e801429b7e5d0f6b21137d99 >>>>>> # first bad commit: [bacf6b499e11760aef73a3bb5ce4e5eea74a3fd4] >>>>>> x86/mm: >>>>>> Use a >>>>>> struct to reduce parameters for SME PGD mapping >>>>>> >>>>>> >>>>>> Configuration is at >>>>>> >>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/jwboyer/fedora.git/commit/?h=rawhide >>>>>> >>>>>> Note that I do think this is something in the Fedora configuration >>>>>> because a generic "make defconfig" booted just fine. >>>>> >>>>> >>>>> But maybe some of the Fedora patches ? >>>>> >>>>> Can you try an kernel with the config but without any patches ? >>>>> Or a defconfig and just enable CONFIG_AMD_MEM_ENCRYPT ? >>>>> >>>> >>>> The bisect was a vanilla kernel without Fedora patches. >>> >>> Ok . I did an build ( v4.15-rc8-225-g8dd903d2cf7b ) on my AMD >>> Workstation ( EPYC CPU ) >> >> I've tried multiple config combinations on my EPYC system and have not >> been able to reproduce this issue and have not had any boot issues with >> mem_encrypt=on or mem_encrypt=off. I don't have access to a non-AMD box >> at the moment, but I'm really scratching my head on this one. >> >>> with your 64bit config and one on the Ideapad ( Intel i7-6498DU ) .. >>> I disabled Selinux since I don't use it here and module signing. >>> >>> Also with your config my serial setup won't work and the kernel hangs >>> but mem_encrypt=on/off works just fine. >> >> If your using the EPYC serial device and you haven't enabled legacy >> serial device support (if your BIOS supports that), then you're using >> it as a platform device. The fedora config has not set the >> CONFIG_X86_AMD_PLATFORM_DEVICE setting so you won't get the module >> to load and give you serial output. >> >> I'm confused when you say the kernel hangs but mem_encrypt=on/off works >> just fine, can you explain that a bit more? >> >>> >>> Also I notice on the Workstation it takes forever to boot untill >>> 'DMA-API' reports out-of-memory >>> ( dunno how much memory it need but the box has 128GB of RAM ).. >> > > The machines I have are a Lenovo X1 Carbon and a Lenovo T470s. > A Lenovo X220 ThinkPad also reported the problem. > > If I comment out sme_encrypt_kernel it boots: > > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index 7ba5d819ebe3..443ef5d3f1fa 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -158,7 +158,7 @@ unsigned long __head __startup_64(unsigned long > physaddr, > *p += load_delta - sme_get_me_mask(); > > /* Encrypt the kernel and related (if SME is active) */ > - sme_encrypt_kernel(bp); > + //sme_encrypt_kernel(bp); > > /* > * Return the SME encryption mask (if SME is active) to be used > as a > > > Interestingly, I tried to print the values in sme_active > (sme_me_mask , sev_enabled) followed by a return at the > very start of sme_encrypt_kernel and that rebooted as well, > vs booting if I just kept the return. sme_me_mask and > sev_enabled are explicitly marked as being in .data, > is it possible they are ending up in a section that isn't > yet mapped or did I hit print too early? > > Thanks, > Laura >
One last note: This was built with gcc 7.2.1
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