linux-kernel - Re: [PATCH] KVM: SVM: Update destination when updating pi irte

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Message-ID: <ZGOnPMTEKqRq89jt@google.com>
Date:   Tue, 16 May 2023 08:54:36 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     "dengqiao.joey" <dengqiao.joey@...edance.com>
Cc:     pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: SVM: Update destination when updating pi irte

On Tue, May 16, 2023, dengqiao.joey wrote:
> Destination of irte will be cleard by IOMMU driver when updating irte.
> It will only be set correctly in vcpu_load. IOMMU will deliver the
> doorbell message to the wrong physical cpu before vcpu_load is executed.
> That means vcpu can not recognize interrupt delivery during the time of
> non-root mode.

I suspect this is actually a bug in amd_iommu_activate_guest_mode().  Does the
below fix the issue?  If so, can you give a Tested-by and/or Reviewed-by on the
posted patch[*]?

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 5a505ba5467e..fbe77ee2d26c 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3484,8 +3484,7 @@ int amd_iommu_activate_guest_mode(void *data)
 	struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
 	u64 valid;
 
-	if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) ||
-	    !entry || entry->lo.fields_vapic.guest_mode)
+	if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) || !entry)
 		return 0;
 
 	valid = entry->lo.fields_vapic.valid;

[*] https://lore.kernel.org/all/20230419201154.83880-2-joao.m.martins@oracle.com