PCI: hv: Add vPCI version protocol negotiation

Hyper-V vPCI offers different protocol versions.  Add the infra for
negotiating the one to use.

Signed-off-by: Jork Loeser <jloeser@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index cf70fbc8e92913cafdb83749f8d30854e6315f9a..4a8a21e37b8efc8ba95b7a219260387e666d190b 100644 (file)
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -64,22 +64,37 @@
  * major version.
  */
 
-#define PCI_MAKE_VERSION(major, minor) ((u32)(((major) << 16) | (major)))
+#define PCI_MAKE_VERSION(major, minor) ((u32)(((major) << 16) | (minor)))
 #define PCI_MAJOR_VERSION(version) ((u32)(version) >> 16)
 #define PCI_MINOR_VERSION(version) ((u32)(version) & 0xff)
 
-enum {
-       PCI_PROTOCOL_VERSION_1_1 = PCI_MAKE_VERSION(1, 1),
-       PCI_PROTOCOL_VERSION_CURRENT = PCI_PROTOCOL_VERSION_1_1
+enum pci_protocol_version_t {
+       PCI_PROTOCOL_VERSION_1_1 = PCI_MAKE_VERSION(1, 1),      /* Win10 */
 };
 
 #define CPU_AFFINITY_ALL       -1ULL
+
+/*
+ * Supported protocol versions in the order of probing - highest go
+ * first.
+ */
+static enum pci_protocol_version_t pci_protocol_versions[] = {
+       PCI_PROTOCOL_VERSION_1_1,
+};
+
+/*
+ * Protocol version negotiated by hv_pci_protocol_negotiation().
+ */
+static enum pci_protocol_version_t pci_protocol_version;
+
 #define PCI_CONFIG_MMIO_LENGTH 0x2000
 #define CFG_PAGE_OFFSET 0x1000
 #define CFG_PAGE_SIZE (PCI_CONFIG_MMIO_LENGTH - CFG_PAGE_OFFSET)
 
 #define MAX_SUPPORTED_MSI_MESSAGES 0x400
 
+#define STATUS_REVISION_MISMATCH 0xC0000059
+
 /*
  * Message Types
  */
@@ -1849,6 +1864,7 @@ static int hv_pci_protocol_negotiation(struct hv_device *hdev)
        struct hv_pci_compl comp_pkt;
        struct pci_packet *pkt;
        int ret;
+       int i;
 
        /*
         * Initiate the handshake with the host and negotiate
@@ -1865,26 +1881,44 @@ static int hv_pci_protocol_negotiation(struct hv_device *hdev)
        pkt->compl_ctxt = &comp_pkt;
        version_req = (struct pci_version_request *)&pkt->message;
        version_req->message_type.type = PCI_QUERY_PROTOCOL_VERSION;
-       version_req->protocol_version = PCI_PROTOCOL_VERSION_CURRENT;
 
-       ret = vmbus_sendpacket(hdev->channel, version_req,
-                              sizeof(struct pci_version_request),
-                              (unsigned long)pkt, VM_PKT_DATA_INBAND,
-                              VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-       if (ret)
-               goto exit;
+       for (i = 0; i < ARRAY_SIZE(pci_protocol_versions); i++) {
+               version_req->protocol_version = pci_protocol_versions[i];
+               ret = vmbus_sendpacket(hdev->channel, version_req,
+                               sizeof(struct pci_version_request),
+                               (unsigned long)pkt, VM_PKT_DATA_INBAND,
+                               VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+               if (ret) {
+                       dev_err(&hdev->device,
+                               "PCI Pass-through VSP failed sending version reqquest: %#x",
+                               ret);
+                       goto exit;
+               }
 
-       wait_for_completion(&comp_pkt.host_event);
+               wait_for_completion(&comp_pkt.host_event);
 
-       if (comp_pkt.completion_status < 0) {
-               dev_err(&hdev->device,
-                       "PCI Pass-through VSP failed version request %x\n",
-                       comp_pkt.completion_status);
-               ret = -EPROTO;
-               goto exit;
+               if (comp_pkt.completion_status >= 0) {
+                       pci_protocol_version = pci_protocol_versions[i];
+                       dev_info(&hdev->device,
+                               "PCI VMBus probing: Using version %#x\n",
+                               pci_protocol_version);
+                       goto exit;
+               }
+
+               if (comp_pkt.completion_status != STATUS_REVISION_MISMATCH) {
+                       dev_err(&hdev->device,
+                               "PCI Pass-through VSP failed version request: %#x",
+                               comp_pkt.completion_status);
+                       ret = -EPROTO;
+                       goto exit;
+               }
+
+               reinit_completion(&comp_pkt.host_event);
        }
 
-       ret = 0;
+       dev_err(&hdev->device,
+               "PCI pass-through VSP failed to find supported version");
+       ret = -EPROTO;
 
 exit:
        kfree(pkt);