linux-kernel - Re: [RFC PATCH v1 26/38] KVM: arm64: Add exit handler related to device assignment

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Message-ID: <20250730153506.00006280@huawei.com>
Date: Wed, 30 Jul 2025 15:35:06 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
CC: <linux-coco@...ts.linux.dev>, <kvmarm@...ts.linux.dev>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <aik@....com>,
	<lukas@...ner.de>, Samuel Ortiz <sameo@...osinc.com>, Xu Yilun
	<yilun.xu@...ux.intel.com>, Jason Gunthorpe <jgg@...pe.ca>, "Suzuki K
 Poulose" <Suzuki.Poulose@....com>, Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>
Subject: Re: [RFC PATCH v1 26/38] KVM: arm64: Add exit handler related to
 device assignment

On Mon, 28 Jul 2025 19:22:03 +0530
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org> wrote:

> Different RSI calls related to DA result in REC exits. Add a facility to
> register handlers for handling these REC exits.
> 
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@...nel.org>


> diff --git a/arch/arm64/include/asm/rmi_smc.h b/arch/arm64/include/asm/rmi_smc.h
> index c6e16ab608e1..a5ef68b62bc0 100644
> --- a/arch/arm64/include/asm/rmi_smc.h
> +++ b/arch/arm64/include/asm/rmi_smc.h

> diff --git a/arch/arm64/kvm/rme-exit.c b/arch/arm64/kvm/rme-exit.c
> index 1a8ca7526863..25948207fc5b 100644
> --- a/arch/arm64/kvm/rme-exit.c
> +++ b/arch/arm64/kvm/rme-exit.c


> +static int rec_exit_dev_mem_map(struct kvm_vcpu *vcpu)
> +{
> +	int ret;
> +	struct realm_rec *rec = &vcpu->arch.rec;
> +
> +	if (realm_exit_dev_mem_map_handler) {
> +		ret = (*realm_exit_dev_mem_map_handler)(rec);
> +	} else {
> +		kvm_pr_unimpl("Unsupported exit reason: %u\n",
> +			      rec->run->exit.exit_reason);
> +		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> +		ret = 0;

I guess maybe this gets more complex later, but right now
		return 0;

And maybe return in the if branch as well.
Same for other similar code in this patch.

> +	}
> +	return ret;
> +}
> +
>  static void update_arch_timer_irq_lines(struct kvm_vcpu *vcpu)
>  {
>  	struct realm_rec *rec = &vcpu->arch.rec;
> @@ -198,6 +252,12 @@ int handle_rec_exit(struct kvm_vcpu *vcpu, int rec_run_ret)
>  		return rec_exit_ripas_change(vcpu);
>  	case RMI_EXIT_HOST_CALL:
>  		return rec_exit_host_call(vcpu);
> +	case RMI_EXIT_VDEV_REQUEST:
> +		return rec_exit_vdev_request(vcpu);
> +	case RMI_EXIT_VDEV_COMM:
> +		return rec_exit_vdev_communication(vcpu);
> +	case RMI_EXIT_DEV_MEM_MAP:
> +		return rec_exit_dev_mem_map(vcpu);
>  	}
>  
>  	kvm_pr_unimpl("Unsupported exit reason: %u\n",