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PCI/P2PDMA: Simplify distance calculation
Merge __calc_map_type_and_dist() and calc_map_type_and_dist_warn() into calc_map_type_and_dist() to simplify the code a bit. This now means we add the devfn strings to the acs_buf unconditionally even if the buffer is not printed, but that is not a lot of overhead and keeps the code much simpler. Link: https://lore.kernel.org/r/20210614055310.3960791-1-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
This commit is contained in:
Christoph Hellwig
Bjorn Helgaas
parent
3ec0c3ec2d
commit
d1b8dc09dd
@ -388,79 +388,6 @@ static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b,
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return false;
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}
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static enum pci_p2pdma_map_type
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__calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
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int *dist, bool *acs_redirects, struct seq_buf *acs_list)
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{
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struct pci_dev *a = provider, *b = client, *bb;
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int dist_a = 0;
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int dist_b = 0;
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int acs_cnt = 0;
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if (acs_redirects)
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*acs_redirects = false;
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/*
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* Note, we don't need to take references to devices returned by
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* pci_upstream_bridge() seeing we hold a reference to a child
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* device which will already hold a reference to the upstream bridge.
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*/
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while (a) {
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dist_b = 0;
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if (pci_bridge_has_acs_redir(a)) {
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seq_buf_print_bus_devfn(acs_list, a);
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acs_cnt++;
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}
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bb = b;
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while (bb) {
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if (a == bb)
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goto check_b_path_acs;
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bb = pci_upstream_bridge(bb);
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dist_b++;
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}
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a = pci_upstream_bridge(a);
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dist_a++;
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}
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if (dist)
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*dist = dist_a + dist_b;
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return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
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check_b_path_acs:
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bb = b;
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while (bb) {
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if (a == bb)
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break;
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if (pci_bridge_has_acs_redir(bb)) {
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seq_buf_print_bus_devfn(acs_list, bb);
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acs_cnt++;
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}
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bb = pci_upstream_bridge(bb);
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}
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if (dist)
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*dist = dist_a + dist_b;
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if (acs_cnt) {
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if (acs_redirects)
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*acs_redirects = true;
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return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
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}
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return PCI_P2PDMA_MAP_BUS_ADDR;
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}
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static unsigned long map_types_idx(struct pci_dev *client)
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{
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return (pci_domain_nr(client->bus) << 16) |
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@ -502,63 +429,96 @@ static unsigned long map_types_idx(struct pci_dev *client)
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* PCI_P2PDMA_MAP_THRU_HOST_BRIDGE with the distance set to the number of
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* ports per above. If the device is not in the whitelist, return
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* PCI_P2PDMA_MAP_NOT_SUPPORTED.
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*
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* If any ACS redirect bits are set, then acs_redirects boolean will be set
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* to true and their PCI device names will be appended to the acs_list
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* seq_buf. This seq_buf is used to print a warning informing the user how
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* to disable ACS using a command line parameter. (See
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* calc_map_type_and_dist_warn() below)
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*/
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static enum pci_p2pdma_map_type
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calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
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int *dist, bool *acs_redirects, struct seq_buf *acs_list)
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{
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enum pci_p2pdma_map_type map_type;
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map_type = __calc_map_type_and_dist(provider, client, dist,
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acs_redirects, acs_list);
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if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) {
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if (!cpu_supports_p2pdma() &&
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!host_bridge_whitelist(provider, client, acs_redirects))
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map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
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}
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if (provider->p2pdma)
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xa_store(&provider->p2pdma->map_types, map_types_idx(client),
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xa_mk_value(map_type), GFP_KERNEL);
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return map_type;
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}
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static enum pci_p2pdma_map_type
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calc_map_type_and_dist_warn(struct pci_dev *provider, struct pci_dev *client,
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int *dist)
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int *dist, bool verbose)
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{
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enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
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struct pci_dev *a = provider, *b = client, *bb;
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bool acs_redirects = false;
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struct seq_buf acs_list;
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bool acs_redirects;
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int acs_cnt = 0;
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int dist_a = 0;
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int dist_b = 0;
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char buf[128];
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int ret;
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seq_buf_init(&acs_list, buf, sizeof(buf));
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ret = calc_map_type_and_dist(provider, client, dist, &acs_redirects,
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&acs_list);
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if (acs_redirects) {
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/*
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* Note, we don't need to take references to devices returned by
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* pci_upstream_bridge() seeing we hold a reference to a child
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* device which will already hold a reference to the upstream bridge.
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*/
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while (a) {
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dist_b = 0;
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if (pci_bridge_has_acs_redir(a)) {
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seq_buf_print_bus_devfn(&acs_list, a);
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acs_cnt++;
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}
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bb = b;
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while (bb) {
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if (a == bb)
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goto check_b_path_acs;
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bb = pci_upstream_bridge(bb);
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dist_b++;
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}
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a = pci_upstream_bridge(a);
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dist_a++;
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}
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*dist = dist_a + dist_b;
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goto map_through_host_bridge;
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check_b_path_acs:
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bb = b;
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while (bb) {
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if (a == bb)
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break;
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if (pci_bridge_has_acs_redir(bb)) {
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seq_buf_print_bus_devfn(&acs_list, bb);
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acs_cnt++;
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}
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bb = pci_upstream_bridge(bb);
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}
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*dist = dist_a + dist_b;
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if (!acs_cnt) {
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map_type = PCI_P2PDMA_MAP_BUS_ADDR;
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goto done;
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}
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if (verbose) {
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acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */
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pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
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pci_name(provider));
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/* Drop final semicolon */
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acs_list.buffer[acs_list.len-1] = 0;
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pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
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acs_list.buffer);
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}
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acs_redirects = true;
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if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED) {
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pci_warn(client, "cannot be used for peer-to-peer DMA as the client and provider (%s) do not share an upstream bridge or whitelisted host bridge\n",
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pci_name(provider));
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map_through_host_bridge:
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if (!cpu_supports_p2pdma() &&
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!host_bridge_whitelist(provider, client, acs_redirects)) {
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if (verbose)
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pci_warn(client, "cannot be used for peer-to-peer DMA as the client and provider (%s) do not share an upstream bridge or whitelisted host bridge\n",
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pci_name(provider));
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map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
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}
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return ret;
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done:
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if (provider->p2pdma)
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xa_store(&provider->p2pdma->map_types, map_types_idx(client),
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xa_mk_value(map_type), GFP_KERNEL);
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return map_type;
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}
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/**
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@ -599,12 +559,8 @@ int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
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return -1;
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}
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if (verbose)
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map = calc_map_type_and_dist_warn(provider, pci_client,
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&distance);
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else
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map = calc_map_type_and_dist(provider, pci_client,
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&distance, NULL, NULL);
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map = calc_map_type_and_dist(provider, pci_client, &distance,
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verbose);
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pci_dev_put(pci_client);
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