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

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Date:   Wed, 31 Mar 2021 16:28:46 +0100
From:   Alexandru Elisei <alexandru.elisei@....com>
To:     Suzuki K Poulose <suzuki.poulose@....com>,
        Marc Zyngier <maz@...nel.org>
Cc:     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

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?

[1] https://lore.kernel.org/r/20210323180057.263356-1-alexandru.elisei@arm.com

Thanks,
Alex