* Unexpected variation in SYS_ID_AA64MMFR0_EL1
@ 2018-11-30 12:15 Marc Gonzalez
2018-11-30 13:12 ` Ard Biesheuvel
0 siblings, 1 reply; 7+ messages in thread
From: Marc Gonzalez @ 2018-11-30 12:15 UTC (permalink / raw)
To: Suzuki K. Poulose
Cc: Mark Rutland, Catalin Marinas, Dave Martin, Linux ARM,
Bjorn Andersson
Hello,
On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints:
[ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1.
Boot CPU: 0x00000000001122, CPU4: 0x00000000101122
TGran16, [23:20]
Support for 16KB memory translation granule size:
0x1 Indicates that the 16KB granule is supported.
Since this is a pr_warn, I get the feeling something is not quite right.
Is there something to fix? Is it a problem that the big and little cores
don't support exactly the same granule sizes?
Regards.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1 2018-11-30 12:15 Unexpected variation in SYS_ID_AA64MMFR0_EL1 Marc Gonzalez @ 2018-11-30 13:12 ` Ard Biesheuvel 2018-11-30 13:23 ` Suzuki K Poulose 0 siblings, 1 reply; 7+ messages in thread From: Ard Biesheuvel @ 2018-11-30 13:12 UTC (permalink / raw) To: marc.w.gonzalez Cc: Mark Rutland, Suzuki K. Poulose, Catalin Marinas, Bjorn Andersson, Dave Martin, linux-arm-kernel On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote: > > Hello, > > On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: > > [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. > Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 > > TGran16, [23:20] > Support for 16KB memory translation granule size: > 0x1 Indicates that the 16KB granule is supported. > > Since this is a pr_warn, I get the feeling something is not quite right. > Is there something to fix? Is it a problem that the big and little cores > don't support exactly the same granule sizes? > That looks like a false positive to me. We should only care about the page size we are running with. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1 2018-11-30 13:12 ` Ard Biesheuvel @ 2018-11-30 13:23 ` Suzuki K Poulose 2018-11-30 13:24 ` Ard Biesheuvel 2018-12-03 15:32 ` Catalin Marinas 0 siblings, 2 replies; 7+ messages in thread From: Suzuki K Poulose @ 2018-11-30 13:23 UTC (permalink / raw) To: Ard Biesheuvel, marc.w.gonzalez Cc: Mark Rutland, Catalin Marinas, Dave Martin, linux-arm-kernel, Bjorn Andersson On 30/11/2018 13:12, Ard Biesheuvel wrote: > On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote: >> >> Hello, >> >> On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: >> >> [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. >> Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 >> >> TGran16, [23:20] >> Support for 16KB memory translation granule size: >> 0x1 Indicates that the 16KB granule is supported. >> >> Since this is a pr_warn, I get the feeling something is not quite right. >> Is there something to fix? Is it a problem that the big and little cores >> don't support exactly the same granule sizes? >> > > That looks like a false positive to me. We should only care about the > page size we are running with. Unless you run a VM, which is going to use 16K translation. But this may be fine with the current kernels, where we emulate the SANITISED registers for the guests. Cheers Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1 2018-11-30 13:23 ` Suzuki K Poulose @ 2018-11-30 13:24 ` Ard Biesheuvel 2018-12-03 15:32 ` Catalin Marinas 1 sibling, 0 replies; 7+ messages in thread From: Ard Biesheuvel @ 2018-11-30 13:24 UTC (permalink / raw) To: Suzuki K. Poulose Cc: Mark Rutland, marc.w.gonzalez, Catalin Marinas, Bjorn Andersson, Dave Martin, linux-arm-kernel On Fri, 30 Nov 2018 at 14:23, Suzuki K Poulose <suzuki.poulose@arm.com> wrote: > > > > On 30/11/2018 13:12, Ard Biesheuvel wrote: > > On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote: > >> > >> Hello, > >> > >> On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: > >> > >> [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. > >> Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 > >> > >> TGran16, [23:20] > >> Support for 16KB memory translation granule size: > >> 0x1 Indicates that the 16KB granule is supported. > >> > >> Since this is a pr_warn, I get the feeling something is not quite right. > >> Is there something to fix? Is it a problem that the big and little cores > >> don't support exactly the same granule sizes? > >> > > > > That looks like a false positive to me. We should only care about the > > page size we are running with. > > Unless you run a VM, which is going to use 16K translation. Good point. > But this may be > fine with the current kernels, where we emulate the SANITISED registers > for the guests. > > Cheers > Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1 2018-11-30 13:23 ` Suzuki K Poulose 2018-11-30 13:24 ` Ard Biesheuvel @ 2018-12-03 15:32 ` Catalin Marinas 2018-12-05 10:17 ` Suzuki K Poulose 1 sibling, 1 reply; 7+ messages in thread From: Catalin Marinas @ 2018-12-03 15:32 UTC (permalink / raw) To: Suzuki K Poulose Cc: Mark Rutland, marc.w.gonzalez, Ard Biesheuvel, Bjorn Andersson, Dave Martin, linux-arm-kernel On Fri, Nov 30, 2018 at 01:23:28PM +0000, Suzuki K. Poulose wrote: > On 30/11/2018 13:12, Ard Biesheuvel wrote: > > On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote: > > > On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: > > > > > > [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. > > > Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 > > > > > > TGran16, [23:20] > > > Support for 16KB memory translation granule size: > > > 0x1 Indicates that the 16KB granule is supported. > > > > > > Since this is a pr_warn, I get the feeling something is not quite right. > > > Is there something to fix? Is it a problem that the big and little cores > > > don't support exactly the same granule sizes? > > > > > > > That looks like a false positive to me. We should only care about the > > page size we are running with. > > Unless you run a VM, which is going to use 16K translation. But this may be > fine with the current kernels, where we emulate the SANITISED registers > for the guests. I think that's sanitised now for KVM, so we could downgrade the feature to FTR_NONSTRICT. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1 2018-12-03 15:32 ` Catalin Marinas @ 2018-12-05 10:17 ` Suzuki K Poulose 2018-12-05 15:53 ` Catalin Marinas 0 siblings, 1 reply; 7+ messages in thread From: Suzuki K Poulose @ 2018-12-05 10:17 UTC (permalink / raw) To: Catalin Marinas Cc: Mark Rutland, marc.w.gonzalez, Ard Biesheuvel, Bjorn Andersson, Dave Martin, linux-arm-kernel On 03/12/2018 15:32, Catalin Marinas wrote: > On Fri, Nov 30, 2018 at 01:23:28PM +0000, Suzuki K. Poulose wrote: >> On 30/11/2018 13:12, Ard Biesheuvel wrote: >>> On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote: >>>> On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: >>>> >>>> [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. >>>> Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 >>>> >>>> TGran16, [23:20] >>>> Support for 16KB memory translation granule size: >>>> 0x1 Indicates that the 16KB granule is supported. >>>> >>>> Since this is a pr_warn, I get the feeling something is not quite right. >>>> Is there something to fix? Is it a problem that the big and little cores >>>> don't support exactly the same granule sizes? >>>> >>> >>> That looks like a false positive to me. We should only care about the >>> page size we are running with. >> >> Unless you run a VM, which is going to use 16K translation. But this may be >> fine with the current kernels, where we emulate the SANITISED registers >> for the guests. > > I think that's sanitised now for KVM, so we could downgrade the feature > to FTR_NONSTRICT. > Yes, the only caveat is we must make sure that the patch somehow reflect the KVM changes to prevent backports assuming that it is safe to change them without the KVM bits. I will cook something up, along with the other feature bits. Cheers Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Unexpected variation in SYS_ID_AA64MMFR0_EL1 2018-12-05 10:17 ` Suzuki K Poulose @ 2018-12-05 15:53 ` Catalin Marinas 0 siblings, 0 replies; 7+ messages in thread From: Catalin Marinas @ 2018-12-05 15:53 UTC (permalink / raw) To: Suzuki K Poulose Cc: Mark Rutland, Ard Biesheuvel, marc.w.gonzalez, Bjorn Andersson, Dave Martin, linux-arm-kernel On Wed, Dec 05, 2018 at 10:17:38AM +0000, Suzuki K Poulose wrote: > > > On 03/12/2018 15:32, Catalin Marinas wrote: > > On Fri, Nov 30, 2018 at 01:23:28PM +0000, Suzuki K. Poulose wrote: > > > On 30/11/2018 13:12, Ard Biesheuvel wrote: > > > > On Fri, 30 Nov 2018 at 13:15, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote: > > > > > On an APQ8098-based system, for cores 4-7 (little cores?), the kernel prints: > > > > > > > > > > [ 0.179055] CPU features: SANITY CHECK: Unexpected variation in SYS_ID_AA64MMFR0_EL1. > > > > > Boot CPU: 0x00000000001122, CPU4: 0x00000000101122 > > > > > > > > > > TGran16, [23:20] > > > > > Support for 16KB memory translation granule size: > > > > > 0x1 Indicates that the 16KB granule is supported. > > > > > > > > > > Since this is a pr_warn, I get the feeling something is not quite right. > > > > > Is there something to fix? Is it a problem that the big and little cores > > > > > don't support exactly the same granule sizes? > > > > > > > > > > > > > That looks like a false positive to me. We should only care about the > > > > page size we are running with. > > > > > > Unless you run a VM, which is going to use 16K translation. But this may be > > > fine with the current kernels, where we emulate the SANITISED registers > > > for the guests. > > > > I think that's sanitised now for KVM, so we could downgrade the feature > > to FTR_NONSTRICT. > > Yes, the only caveat is we must make sure that the patch somehow reflect > the KVM changes to prevent backports assuming that it is safe to change them > without the KVM bits. We can add a "Cc: stable # <commit-that-fixes-KVM>" to make the requirement clear. We should probably also limit the Cc: stable to the kernel version where KVM started trapping this register. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2018-12-05 15:54 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-11-30 12:15 Unexpected variation in SYS_ID_AA64MMFR0_EL1 Marc Gonzalez 2018-11-30 13:12 ` Ard Biesheuvel 2018-11-30 13:23 ` Suzuki K Poulose 2018-11-30 13:24 ` Ard Biesheuvel 2018-12-03 15:32 ` Catalin Marinas 2018-12-05 10:17 ` Suzuki K Poulose 2018-12-05 15:53 ` Catalin Marinas
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).