linux-kernel - Re: [PATCH v5 07/19] arm64: kvm: Enable access to TRBE support for host

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Message-ID: <871rbvqqpu.wl-maz@kernel.org>
Date:   Wed, 31 Mar 2021 16:37:33 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Alexandru Elisei <alexandru.elisei@....com>
Cc:     Suzuki K Poulose <suzuki.poulose@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        coresight@...ts.linaro.org, mathieu.poirier@...aro.org,
        mike.leach@...aro.org, leo.yan@...aro.org,
        anshuman.khandual@....com, catalin.marinas@....com,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v5 07/19] arm64: kvm: Enable access to TRBE support for host

On Wed, 31 Mar 2021 16:28:46 +0100,
Alexandru Elisei <alexandru.elisei@....com> wrote:
> 
> Hello,
> 
> On 3/30/21 12:12 PM, Suzuki K Poulose wrote:
> > Hi Marc
> >
> > On 30/03/2021 11:12, Marc Zyngier wrote:
> >> Hi Suzuki,
> >>
> >> [+ Alex]
> >>
> >> On Tue, 23 Mar 2021 12:06:35 +0000,
> >> Suzuki K Poulose <suzuki.poulose@....com> wrote:
> >>> [..]
> >>
> >>>   #define MDCR_EL2_TTRF        (1 << 19)
> >>>   #define MDCR_EL2_TPMS        (1 << 14)
> >>>   #define MDCR_EL2_E2PB_MASK    (UL(0x3))
> >>> diff --git a/arch/arm64/include/asm/kvm_host.h
> >>> b/arch/arm64/include/asm/kvm_host.h
> >>> index 3d10e6527f7d..80d0a1a82a4c 100644
> >>> --- a/arch/arm64/include/asm/kvm_host.h
> >>> +++ b/arch/arm64/include/asm/kvm_host.h
> >>> @@ -315,6 +315,8 @@ struct kvm_vcpu_arch {
> >>>           struct kvm_guest_debug_arch regs;
> >>>           /* Statistical profiling extension */
> >>>           u64 pmscr_el1;
> >>> +        /* Self-hosted trace */
> >>> +        u64 trfcr_el1;
> >>>       } host_debug_state;
> >>>         /* VGIC state */
> >>> diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
> >>> index 5eccbd62fec8..05d25e645b46 100644
> >>> --- a/arch/arm64/kernel/hyp-stub.S
> >>> +++ b/arch/arm64/kernel/hyp-stub.S
> >>> @@ -115,9 +115,10 @@ SYM_CODE_START_LOCAL(mutate_to_vhe)
> >>>       mrs_s    x0, SYS_VBAR_EL12
> >>>       msr    vbar_el1, x0
> >>>   -    // Use EL2 translations for SPE and disable access from EL1
> >>> +    // Use EL2 translations for SPE & TRBE and disable access from EL1
> >>>       mrs    x0, mdcr_el2
> >>>       bic    x0, x0, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT)
> >>> +    bic    x0, x0, #(MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT)
> >>>       msr    mdcr_el2, x0
> >>>         // Transfer the MM state from EL1 to EL2
> >>> diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
> >>> index dbc890511631..7b16f42d39f4 100644
> >>> --- a/arch/arm64/kvm/debug.c
> >>> +++ b/arch/arm64/kvm/debug.c
> >>> @@ -89,7 +89,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
> >>>    *  - Debug ROM Address (MDCR_EL2_TDRA)
> >>>    *  - OS related registers (MDCR_EL2_TDOSA)
> >>>    *  - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
> >>> - *  - Self-hosted Trace Filter controls (MDCR_EL2_TTRF)
> >>> + *  - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL2_E2TB)
> >>
> >> For the record, this is likely to conflict with [1], although that
> >> patch still has some issues.
> >
> > Thanks for the heads up. I think that patch will also conflict with my fixes
> > that is queued in kvmarm/fixes.
> 
> How should I proceed with the patch [1]? For the next iteration, should I rebase
> it on top of kvmarm/fixes or on top of kvmarm/fixes + this series?

On top of kvmarm/fixes, please. I'll merge that branch into 5.13
anyway, as it is taking some time to land upstream.

I'll take care of the conflicts, and shout if I need help!

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.