linux-kernel - Re: [PATCH v7 5/10] KVM: arm/arm64: preserve host MDCR

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Date:   Mon, 25 Mar 2019 20:04:05 +0000
From:   Kristina Martsenko <kristina.martsenko@....com>
To:     Amit Daniel Kachhap <amit.kachhap@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Christoffer Dall <christoffer.dall@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Jones <drjones@...hat.com>,
        Dave Martin <Dave.Martin@....com>,
        Ramana Radhakrishnan <ramana.radhakrishnan@....com>,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry@....com>
Subject: Re: [PATCH v7 5/10] KVM: arm/arm64: preserve host MDCR_EL2 value

On 19/03/2019 08:30, Amit Daniel Kachhap wrote:
> Save host MDCR_EL2 value during kvm HYP initialisation and restore
> after every switch from host to guest. There should not be any
> change in functionality due to this.
> 
> The value of mdcr_el2 is now stored in struct kvm_cpu_context as
> both host and guest can now use this field in a common way.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@....com>
> Acked-by: Mark Rutland <mark.rutland@....com>
> Cc: Marc Zyngier <marc.zyngier@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Christoffer Dall <christoffer.dall@....com>
> Cc: kvmarm@...ts.cs.columbia.edu

[...]

>  /**
> - * kvm_arm_init_debug - grab what we need for debug
> - *
> - * Currently the sole task of this function is to retrieve the initial
> - * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
> - * presumably been set-up by some knowledgeable bootcode.
> - *
> - * It is called once per-cpu during CPU hyp initialisation.
> - */
> -
> -void kvm_arm_init_debug(void)
> -{
> -	__this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2));
> -}

The __kvm_get_mdcr_el2 function is no longer used anywhere, so can also
be removed.

Thanks,
Kristina