Re: [PATCH v4] PCI: Accept AtomicOps already enabled by the hypervisor

[sashiko-bot@kernel.org]

> From: Nikola Prica <nikola.prica@amd.com>
> 
> pci_enable_atomic_ops_to_root() currently fails when no Root Port is
> visible. That is common in passthrough guests (ESXi, Hyper-V): the
> endpoint is assigned to the VM, but the guest topology has no Root
> Port above it.
> 
> In those setups the hypervisor may already have enabled AtomicOp
> Requester Enable on the device. If PCI_EXP_DEVCTL2_ATOMIC_REQ is set,
> treat AtomicOps as already enabled and return success instead of
> failing the Root Port walk.
> 
> After 1ae8c4ce1570 ("PCI: Enable AtomicOps only if Root Port
> supports them"), pci_enable_atomic_ops_to_root() always fails if the
> Root Port is not visible.  On systems where the Root Port is not
> visible but *does* support AtomicOps, this is a regression: prior to
> 1ae8c4ce1570, it enabled AtomicOps in the endpoint and returned
> success.
> 
> Fixes: 1ae8c4ce1570 ("PCI: Enable AtomicOps only if Root Port supports them")
> Reviewed-by: Christian König <christian.koenig@amd.com>
> Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
> Tested-by: Gerd Bayer <gbayer@linux.ibm.com>
> Signed-off-by: Nikola Prica <nikola.prica@amd.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260921111903.978687-1-nikprica@amd.com?part=1