From: Joao Martins joao.m.martins@oracle.com
[ Upstream commit ed8a2f4ddef2eaaf864ab1efbbca9788187036ab ]
On KVM GSI routing table updates, specially those where they have vIOMMUs with interrupt remapping enabled (to boot >255vcpus setups without relying on KVM_FEATURE_MSI_EXT_DEST_ID), a VMM may update the backing VF MSIs with a new VCPU affinity.
On AMD with AVIC enabled, the new vcpu affinity info is updated via: avic_pi_update_irte() irq_set_vcpu_affinity() amd_ir_set_vcpu_affinity() amd_iommu_{de}activate_guest_mode()
Where the IRTE[GATag] is updated with the new vcpu affinity. The GATag contains VM ID and VCPU ID, and is used by IOMMU hardware to signal KVM (via GALog) when interrupt cannot be delivered due to vCPU is in blocking state.
The issue is that amd_iommu_activate_guest_mode() will essentially only change IRTE fields on transitions from non-guest-mode to guest-mode and otherwise returns *with no changes to IRTE* on already configured guest-mode interrupts. To the guest this means that the VF interrupts remain affined to the first vCPU they were first configured, and guest will be unable to issue VF interrupts and receive messages like this from spurious interrupts (e.g. from waking the wrong vCPU in GALog):
[ 167.759472] __common_interrupt: 3.34 No irq handler for vector [ 230.680927] mlx5_core 0000:00:02.0: mlx5_cmd_eq_recover:247:(pid 3122): Recovered 1 EQEs on cmd_eq [ 230.681799] mlx5_core 0000:00:02.0: wait_func_handle_exec_timeout:1113:(pid 3122): cmd[0]: CREATE_CQ(0x400) recovered after timeout [ 230.683266] __common_interrupt: 3.34 No irq handler for vector
Given the fact that amd_ir_set_vcpu_affinity() uses amd_iommu_activate_guest_mode() underneath it essentially means that VCPU affinity changes of IRTEs are nops. Fix it by dropping the check for guest-mode at amd_iommu_activate_guest_mode(). Same thing is applicable to amd_iommu_deactivate_guest_mode() although, even if the IRTE doesn't change underlying DestID on the host, the VFIO IRQ handler will still be able to poke at the right guest-vCPU.
Fixes: b9c6ff94e43a ("iommu/amd: Re-factor guest virtual APIC (de-)activation code") Signed-off-by: Joao Martins joao.m.martins@oracle.com Reviewed-by: Suravee Suthikulpanit suravee.suthikulpanit@amd.com Link: https://lore.kernel.org/r/20230419201154.83880-2-joao.m.martins@oracle.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/amd/iommu.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index f216a86d9c817..0a061a196b531 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -3914,8 +3914,7 @@ 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;