PCI/P2PDMA: Allow P2PDMA on AMD Zen and newer CPUs

Allow P2PDMA if the CPU vendor is AMD and family is 0x17 (Zen) or greater.

[bhelgaas: commit log, simplify #if/#else/#endif]
Link: https://lore.kernel.org/r/20200729231844.4653-1-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Huang Rui <ray.huang@amd.com>

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index e8e444e..1ec61fc 100644 (file)
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -273,6 +273,19 @@ static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
        seq_buf_printf(buf, "%s;", pci_name(pdev));
 }
 
+static bool cpu_supports_p2pdma(void)
+{
+#ifdef CONFIG_X86
+       struct cpuinfo_x86 *c = &cpu_data(0);
+
+       /* Any AMD CPU whose family ID is Zen or newer supports p2pdma */
+       if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17)
+               return true;
+#endif
+
+       return false;
+}
+
 static const struct pci_p2pdma_whitelist_entry {
        unsigned short vendor;
        unsigned short device;
@@ -280,11 +293,6 @@ static const struct pci_p2pdma_whitelist_entry {
                REQ_SAME_HOST_BRIDGE    = 1 << 0,
        } flags;
 } pci_p2pdma_whitelist[] = {
-       /* AMD ZEN */
-       {PCI_VENDOR_ID_AMD,     0x1450, 0},
-       {PCI_VENDOR_ID_AMD,     0x15d0, 0},
-       {PCI_VENDOR_ID_AMD,     0x1630, 0},
-
        /* Intel Xeon E5/Core i7 */
        {PCI_VENDOR_ID_INTEL,   0x3c00, REQ_SAME_HOST_BRIDGE},
        {PCI_VENDOR_ID_INTEL,   0x3c01, REQ_SAME_HOST_BRIDGE},
@@ -473,7 +481,8 @@ upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
                                              acs_redirects, acs_list);
 
        if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) {
-               if (!host_bridge_whitelist(provider, client))
+               if (!cpu_supports_p2pdma() &&
+                   !host_bridge_whitelist(provider, client))
                        map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
        }