linux-kernel - Re: [PATCH 26/67] iommu/amd: KVM: SVM: Delete now-unused cached/previous GA tag fields

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Message-ID: <8b061b2d-7137-498e-93b2-0cb714824d7b@redhat.com>
Date: Tue, 8 Apr 2025 18:57:49 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>, Joerg Roedel <joro@...tes.org>,
 David Woodhouse <dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>
Cc: kvm@...r.kernel.org, iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
 Maxim Levitsky <mlevitsk@...hat.com>,
 Joao Martins <joao.m.martins@...cle.com>, David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH 26/67] iommu/amd: KVM: SVM: Delete now-unused
 cached/previous GA tag fields

On 4/4/25 21:38, Sean Christopherson wrote:
> Delete the amd_ir_data.prev_ga_tag field now that all usage is
> superfluous.

This can be moved much earlier (maybe even after patch 10 from a cursory 
look), can't it?  I'd do that to clarify what has been cleaned up at 
which point.

Paolo

> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>   arch/x86/kvm/svm/avic.c             |  2 --
>   drivers/iommu/amd/amd_iommu_types.h |  1 -
>   drivers/iommu/amd/iommu.c           | 10 ----------
>   include/linux/amd-iommu.h           |  1 -
>   4 files changed, 14 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 9024b9fbca53..7f0f6a9cd2e8 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -943,9 +943,7 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
>   		/**
>   		 * Here, pi is used to:
>   		 * - Tell IOMMU to use legacy mode for this interrupt.
> -		 * - Retrieve ga_tag of prior interrupt remapping data.
>   		 */
> -		pi.prev_ga_tag = 0;
>   		pi.is_guest_mode = false;
>   		ret = irq_set_vcpu_affinity(host_irq, &pi);
>   	} else {
> diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
> index 23caea22f8dc..319a1b650b3b 100644
> --- a/drivers/iommu/amd/amd_iommu_types.h
> +++ b/drivers/iommu/amd/amd_iommu_types.h
> @@ -1060,7 +1060,6 @@ struct irq_2_irte {
>   };
>   
>   struct amd_ir_data {
> -	u32 cached_ga_tag;
>   	struct amd_iommu *iommu;
>   	struct irq_2_irte irq_2_irte;
>   	struct msi_msg msi_entry;
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 635774642b89..3c40bc9980b7 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -3858,23 +3858,13 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
>   	ir_data->cfg = irqd_cfg(data);
>   	pi_data->ir_data = ir_data;
>   
> -	pi_data->prev_ga_tag = ir_data->cached_ga_tag;
>   	if (pi_data->is_guest_mode) {
>   		ir_data->ga_root_ptr = (vcpu_pi_info->pi_desc_addr >> 12);
>   		ir_data->ga_vector = vcpu_pi_info->vector;
>   		ir_data->ga_tag = pi_data->ga_tag;
>   		ret = amd_iommu_activate_guest_mode(ir_data);
> -		if (!ret)
> -			ir_data->cached_ga_tag = pi_data->ga_tag;
>   	} else {
>   		ret = amd_iommu_deactivate_guest_mode(ir_data);
> -
> -		/*
> -		 * This communicates the ga_tag back to the caller
> -		 * so that it can do all the necessary clean up.
> -		 */
> -		if (!ret)
> -			ir_data->cached_ga_tag = 0;
>   	}
>   
>   	return ret;
> diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
> index 4f433ef39188..deeefc92a5cf 100644
> --- a/include/linux/amd-iommu.h
> +++ b/include/linux/amd-iommu.h
> @@ -19,7 +19,6 @@ struct amd_iommu;
>    */
>   struct amd_iommu_pi_data {
>   	u32 ga_tag;
> -	u32 prev_ga_tag;
>   	bool is_guest_mode;
>   	struct vcpu_data *vcpu_data;
>   	void *ir_data;