[v3] KVM: iommu: Overhaul device posted IRQs support

[PATCH v3 01/62] KVM: arm64: Explicitly treat routing entry type changes as changes

Posted by Sean Christopherson 4 months ago

Explicitly treat type differences as GSI routing changes, as comparing MSI
data between two entries could get a false negative, e.g. if userspace
changed the type but left the type-specific data as-

Note, the same bug was fixed in x86 by commit bcda70c56f3e ("KVM: x86:
Explicitly treat routing entry type changes as changes").

Fixes: 4bf3693d36af ("KVM: arm64: Unmap vLPIs affected by changes to GSI routing information")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/kvm/arm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index de2b4e9c9f9f..38a91bb5d4c7 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2764,7 +2764,8 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
 bool kvm_arch_irqfd_route_changed(struct kvm_kernel_irq_routing_entry *old,
 				  struct kvm_kernel_irq_routing_entry *new)
 {
-	if (new->type != KVM_IRQ_ROUTING_MSI)
+	if (old->type != KVM_IRQ_ROUTING_MSI ||
+	    new->type != KVM_IRQ_ROUTING_MSI)
 		return true;
 
 	return memcmp(&old->msi, &new->msi, sizeof(new->msi));
-- 
2.50.0.rc1.591.g9c95f17f64-goog

Re: [PATCH v3 01/62] KVM: arm64: Explicitly treat routing entry type changes as changes

Posted by Oliver Upton 3 months, 4 weeks ago

On Wed, Jun 11, 2025 at 03:45:04PM -0700, Sean Christopherson wrote:
> Explicitly treat type differences as GSI routing changes, as comparing MSI
> data between two entries could get a false negative, e.g. if userspace
> changed the type but left the type-specific data as-
> 
> Note, the same bug was fixed in x86 by commit bcda70c56f3e ("KVM: x86:
> Explicitly treat routing entry type changes as changes").

Yeah, I'll let you guess where I got the idea from...

> Fixes: 4bf3693d36af ("KVM: arm64: Unmap vLPIs affected by changes to GSI routing information")
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>

Thanks,
Oliver

Re: (subset) [PATCH v3 01/62] KVM: arm64: Explicitly treat routing entry type changes as changes

Posted by Marc Zyngier 3 months, 3 weeks ago

On Wed, 11 Jun 2025 15:45:04 -0700, Sean Christopherson wrote:
> Explicitly treat type differences as GSI routing changes, as comparing MSI
> data between two entries could get a false negative, e.g. if userspace
> changed the type but left the type-specific data as-
> 
> Note, the same bug was fixed in x86 by commit bcda70c56f3e ("KVM: x86:
> Explicitly treat routing entry type changes as changes").
> 
> [...]

Applied to fixes, thanks!

[01/62] KVM: arm64: Explicitly treat routing entry type changes as changes
        commit: 1fbe6861a6d9a942fb8ab8677ddf1ecb86b1af60

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.