Messages in this thread | | | Subject | Re: [PATCH V3 10/14] arm64: nvhe: Allow TRBE access at EL1 | From | Suzuki K Poulose <> | Date | Thu, 28 Jan 2021 09:48:42 +0000 |
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On 1/28/21 9:46 AM, Marc Zyngier wrote: > On 2021-01-28 09:34, Suzuki K Poulose wrote: >> On 1/27/21 9:58 AM, Marc Zyngier wrote: >>> On 2021-01-27 08:55, Anshuman Khandual wrote: >>>> From: Suzuki K Poulose <suzuki.poulose@arm.com> >>>> >>>> When the kernel is booted at EL2 in a nvhe configuration, >>>> enable the TRBE access to the EL1. The EL1 still can't trace >>>> EL2, unless EL2 permits explicitly via TRFCR_EL2.E2TRE. >>>> >>>> Cc: Will Deacon <will@kernel.org> >>>> Cc: Catalin Marinas <catalin.marinas@arm.com> >>>> Cc: Marc Zyngier <maz@kernel.org> >>>> Cc: Mark Rutland <mark.rutland@arm.com> >>>> cc: Anshuman Khandual <anshuman.khandual@arm.com> >>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >>> >>> Acked-by: Marc Zyngier <maz@kernel.org> >>> >>> One comment below, though: >>> >>>> --- >>>> arch/arm64/include/asm/el2_setup.h | 19 +++++++++++++++++++ >>>> arch/arm64/include/asm/kvm_arm.h | 2 ++ >>>> 2 files changed, 21 insertions(+) >>>> >>>> diff --git a/arch/arm64/include/asm/el2_setup.h >>>> b/arch/arm64/include/asm/el2_setup.h >>>> index a7f5a1b..05ecce9 100644 >>>> --- a/arch/arm64/include/asm/el2_setup.h >>>> +++ b/arch/arm64/include/asm/el2_setup.h >>>> @@ -72,6 +72,25 @@ >>>> .endif >>>> >>>> 3: >>>> + >>>> +.ifeqs "\mode", "nvhe" >>>> + /* >>>> + * If the Trace Buffer is available, allow >>>> + * the EL1 to own it. Note that EL1 cannot >>>> + * trace the EL2, as it is prevented by >>>> + * TRFCR_EL2.E2TRE == 0. >>>> + */ >>>> + ubfx x0, x1, #ID_AA64DFR0_TRBE_SHIFT, #4 >>>> + cbz x0, 1f >>>> + >>>> + mrs_s x0, SYS_TRBIDR_EL1 >>>> + and x0, x0, TRBIDR_PROG >>>> + cbnz x0, 1f >>>> + mov x0, #(MDCR_EL2_E2TB_EL1_OWN << MDCR_EL2_E2TB_SHIFT) >>>> + orr x2, x2, x0 >>>> +.endif >>>> + >>>> +1: >>> >>> Note that this will (badly) conflict with the late-VHE patches[1], >>> where this code path has been reworked. >> >> Thanks for the heads up. We will need to see how things get merged. >> Ideally this patch and the previous one (TRBE definitions could go >> via the arm64 tree / kvm tree), in which case we could rebase these >> two patches on the respective tree. > > I think the current plan of action is to go via the arm64 tree, > given that there is nothing really KVM specific there. I'll respin > the series one last (hopefully!) time on Monday. Let me know if > you need a hand with the rebasing.
Sounds good, will rebase it on top of that then.
Cheers Suzuki
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