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Date:   Thu, 04 Feb 2021 09:50:01 +0000
From:   Marc Zyngier <maz@kernel.org>
To:     Will Deacon <will@kernel.org>,
        Alexandru Elisei <alexandru.elisei@arm.com>
Cc:     linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        linux-kernel@vger.kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        David Brazdil <dbrazdil@google.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Jing Zhang <jingzhangos@google.com>,
        Ajay Patil <pajay@qti.qualcomm.com>,
        Prasad Sodagudi <psodagud@codeaurora.org>,
        Srinivas Ramana <sramana@codeaurora.org>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        kernel-team@android.com
Subject: Re: [PATCH v6 06/21] arm64: Move VHE-specific SPE setup to
 mutate_to_vhe()
In-Reply-To: <20210204093427.GB20244@willie-the-truck>
References: <20210201115637.3123740-1-maz@kernel.org>
 <20210201115637.3123740-7-maz@kernel.org>
 <20210203211319.GA19694@willie-the-truck>
 <a660fd06d43451b4693fbb65f2ee1b56@kernel.org>
 <20210204093427.GB20244@willie-the-truck>
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On 2021-02-04 09:34, Will Deacon wrote:
> On Thu, Feb 04, 2021 at 09:30:08AM +0000, Marc Zyngier wrote:

[...]

>> I think the following patch addresses the above issue, which I'll 
>> squash
>> with the original patch. Please shout if I missed anything.
>> 
>> Thanks,
>> 
>>         M.
>> 
>> diff --git a/arch/arm64/kernel/hyp-stub.S 
>> b/arch/arm64/kernel/hyp-stub.S
>> index aa7e8d592295..3e08dcc924b5 100644
>> --- a/arch/arm64/kernel/hyp-stub.S
>> +++ b/arch/arm64/kernel/hyp-stub.S
>> @@ -115,29 +115,9 @@ SYM_CODE_START_LOCAL(mutate_to_vhe)
>>  	mrs_s	x0, SYS_VBAR_EL12
>>  	msr	vbar_el1, x0
>> 
>> -	// Fixup SPE configuration, if supported...
>> -	mrs	x1, id_aa64dfr0_el1
>> -	ubfx	x1, x1, #ID_AA64DFR0_PMSVER_SHIFT, #4
>> -	mov	x2, xzr
>> -	cbz	x1, skip_spe
>> -
>> -	// ... and not owned by EL3
>> -	mrs_s	x0, SYS_PMBIDR_EL1
>> -	and	x0, x0, #(1 << SYS_PMBIDR_EL1_P_SHIFT)
>> -	cbnz	x0, skip_spe
>> -
>> -	// Let the SPE driver in control of the sampling
>> -	mrs_s	x0, SYS_PMSCR_EL1
>> -	bic	x0, x0, #(1 << SYS_PMSCR_EL2_PCT_SHIFT)
>> -	bic	x0, x0, #(1 << SYS_PMSCR_EL2_PA_SHIFT)
>> -	msr_s	SYS_PMSCR_EL1, x0
>> -	mov	x2, #MDCR_EL2_TPMS
>> -
>> -skip_spe:
>> -	// For VHE, use EL2 translation and disable access from EL1
>> +	// Use EL2 translations for SPE and disable access from EL1
>>  	mrs	x0, mdcr_el2
>>  	bic	x0, x0, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT)
>> -	orr	x0, x0, x2
>>  	msr	mdcr_el2, x0
> 
> Looks a tonne better, thanks! Be nice if somebody could test it for us.

SPE-equipped machines are the silicon equivalent of hen's teeth...

Alex, any chance you could give this a go?

         M.
-- 
Jazz is not dead. It just smells funny...