Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] pci/p2pdma: pcim_p2pdma_set_ats_per_mapping() silently fails for pure clients --
commit 39432dea495f68fb0a21d0daa1f31ba24e130b39 Author: Leon Romanovsky <[email protected]> PCI/P2PDMA: Evaluate the ATS path for clients with ATS enabled P2PDMA assumes every client issues Untranslated Requests. A device with ATS enabled may translate any address it is handed, including a bus address, and Translation Blocking can reject its Translated Requests on a route the Untranslated answer called usable. This commit takes the Address Type from its ATS Enable bit and avoids handing such a client bus addresses unless the client declared per-mapping ATS. > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 6a63901c65fb6..9c0943fdb3e36 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c [ ... ] > @@ -1633,6 +1674,9 @@ pci_p2pdma_map_type_tlp(struct p2pdma_provider > *provider, struct device *dev, > cache_index = map_types_idx(client); > > rcu_read_lock(); > + /* The declaration belongs to the client, the cache to the provider. */ > + p2pdma = rcu_dereference(client->p2pdma); > + per_mapping = p2pdma && p2pdma->ats_per_mapping; [Severity: High] Does this code handle pure P2PDMA clients correctly? Since pure clients (devices initiating P2P transfers but not providing memory) have no mechanism or reason to call pcim_p2pdma_init(), client->p2pdma will be NULL for them. This means when they call pcim_p2pdma_set_ats_per_mapping(), it silently returns and drops the configuration: drivers/pci/p2pdma.c:pcim_p2pdma_set_ats_per_mapping() { ... p2p = rcu_dereference_protected(pdev->p2pdma, 1); if (!p2p) /* * ats_per_mapping is a performance optimization, ... */ return; p2p->ats_per_mapping = true; } Because client->p2pdma is NULL, per_mapping will always evaluate to false here in pci_p2pdma_map_type_tlp(). This leads to pci_p2pdma_client_map_type() incorrectly overriding the map type, which could return PCI_P2PDMA_MAP_NOT_SUPPORTED and break P2P transfers that should have been permitted. How should pure clients register their ATS per-mapping capability if they do not initialize pdev->p2pdma? > p2pdma = rcu_dereference(pdev->p2pdma); > > if (p2pdma) -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=17
