Re: [PATCH v2 03/11] KVM: arm64: Encapsulate reset request logic in a helper function

From: Andrew Jones <drjones@redhat.com>
To: Oliver Upton <oupton@google.com>
Cc: kvmarm@lists.cs.columbia.edu, Marc Zyngier <maz@kernel.org>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Peter Shier <pshier@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Reiji Watanabe <reijiw@google.com>,
	Raghavendra Rao Anata <rananta@google.com>,
	kvm@vger.kernel.org
Subject: Re: [PATCH v2 03/11] KVM: arm64: Encapsulate reset request logic in a helper function
Date: Tue, 5 Oct 2021 15:35:15 +0200	[thread overview]
Message-ID: <20211005133515.nj6erqoct65esbb6@gator.home> (raw)
In-Reply-To: <20210923191610.3814698-4-oupton@google.com>

On Thu, Sep 23, 2021 at 07:16:02PM +0000, Oliver Upton wrote:
> In its implementation of the PSCI function, KVM needs to request that a
> target vCPU resets before its next entry into the guest. Wrap the logic
> for requesting a reset in a function for later use by other implemented
> PSCI calls.
> 
> No functional change intended.
> 
> Signed-off-by: Oliver Upton <oupton@google.com>
> ---
>  arch/arm64/kvm/psci.c | 59 +++++++++++++++++++++++++------------------
>  1 file changed, 35 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> index 310b9cb2b32b..bb59b692998b 100644
> --- a/arch/arm64/kvm/psci.c
> +++ b/arch/arm64/kvm/psci.c
> @@ -64,9 +64,40 @@ static inline bool kvm_psci_valid_affinity(unsigned long affinity)
>  	return !(affinity & ~MPIDR_HWID_BITMASK);
>  }
>  
> -static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
> +static void kvm_psci_vcpu_request_reset(struct kvm_vcpu *vcpu,
> +					unsigned long entry_addr,
> +					unsigned long context_id,
> +					bool big_endian)
>  {
>  	struct vcpu_reset_state *reset_state;
> +
> +	lockdep_assert_held(&vcpu->kvm->lock);
> +
> +	reset_state = &vcpu->arch.reset_state;
> +	reset_state->pc = entry_addr;
> +
> +	/* Propagate caller endianness */
> +	reset_state->be = big_endian;
> +
> +	/*
> +	 * NOTE: We always update r0 (or x0) because for PSCI v0.1
> +	 * the general purpose registers are undefined upon CPU_ON.
> +	 */
> +	reset_state->r0 = context_id;
> +
> +	WRITE_ONCE(reset_state->reset, true);
> +	kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
> +
> +	/*
> +	 * Make sure the reset request is observed if the change to
> +	 * power_state is observed.
> +	 */
> +	smp_wmb();
> +	vcpu->arch.power_off = false;
> +}
> +
> +static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
> +{
>  	struct kvm *kvm = source_vcpu->kvm;
>  	struct kvm_vcpu *vcpu = NULL;
>  	unsigned long cpu_id;
> @@ -90,29 +121,9 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
>  			return PSCI_RET_INVALID_PARAMS;
>  	}
>  
> -	reset_state = &vcpu->arch.reset_state;
> -
> -	reset_state->pc = smccc_get_arg2(source_vcpu);
> -
> -	/* Propagate caller endianness */
> -	reset_state->be = kvm_vcpu_is_be(source_vcpu);
> -
> -	/*
> -	 * NOTE: We always update r0 (or x0) because for PSCI v0.1
> -	 * the general purpose registers are undefined upon CPU_ON.
> -	 */
> -	reset_state->r0 = smccc_get_arg3(source_vcpu);
> -
> -	WRITE_ONCE(reset_state->reset, true);
> -	kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
> -
> -	/*
> -	 * Make sure the reset request is observed if the change to
> -	 * power_state is observed.
> -	 */
> -	smp_wmb();
> -
> -	vcpu->arch.power_off = false;
> +	kvm_psci_vcpu_request_reset(vcpu, smccc_get_arg2(source_vcpu),
> +				    smccc_get_arg3(source_vcpu),
> +				    kvm_vcpu_is_be(source_vcpu));
>  	kvm_vcpu_wake_up(vcpu);
>  
>  	return PSCI_RET_SUCCESS;
> -- 
> 2.33.0.685.g46640cef36-goog
>

Reviewed-by: Andrew Jones <drjones@redhat.com>