linux-kernel - Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set for non-vCPU IRTE

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Message-ID: <686dced1-17e6-4ba4-99c3-a7b8672b0e0d@amd.com>
Date: Fri, 11 Apr 2025 14:04:27 +0530
From: Sairaj Kodilkar <sarunkod@....com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini
	<pbonzini@...hat.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>,
	Vasant Hegde <vasant.hegde@....com>, Naveen N Rao <naveen.rao@....com>,
	"Suthikulpanit, Suravee" <suravee.suthikulpanit@....com>
Subject: Re: [PATCH 05/67] iommu/amd: Return an error if vCPU affinity is set
 for non-vCPU IRTE

On 4/5/2025 1:08 AM, Sean Christopherson wrote:
> Return -EINVAL instead of success if amd_ir_set_vcpu_affinity() is
> invoked without use_vapic; lying to KVM about whether or not the IRTE was
> configured to post IRQs is all kinds of bad.
> 
> Fixes: d98de49a53e4 ("iommu/amd: Enable vAPIC interrupt remapping mode by default")
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>   drivers/iommu/amd/iommu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index cd5116d8c3b2..b3a01b7757ee 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -3850,7 +3850,7 @@ static int amd_ir_set_vcpu_affinity(struct irq_data *data, void *vcpu_info)
>   	 * we should not modify the IRTE
>   	 */
>   	if (!dev_data || !dev_data->use_vapic)
> -		return 0;
> +		return -EINVAL;
>   

Hi Sean,
you can update following functions as well to return error when
IOMMU is using legacy interrupt mode.
1. amd_iommu_update_ga
2. amd_iommu_activate_guest_mode
3. amd_iommu_deactivate_guest_mode

Currently these functions return 0 to the kvm layer when they fail to
set the IRTE.

Regards
Sairaj Kodilkar