[PATCH 1/2] Drivers: hv: vmbus: add support to ignore certain PCIE devices

From: longli
Date: Mon Jun 07 2021 - 21:04:50 EST


From: Long Li <longli@xxxxxxxxxxxxx>

When Hyper-v presents a FlexIOV device to VMBUS, this device has its VMBUS
channel and a PCIE channel. The PCIE channel is not used in Linux and does
not have a backing PCIE device on Hyper-v. For such FlexIOV devices, add
the code to ignore those PCIE devices so they are not getting probed by the
PCI subsystem.

Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu@xxxxxxxxxx>
Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>
Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
---
drivers/hv/channel_mgmt.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index caf6d0c..6fd7ae5 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -26,6 +26,20 @@

static void init_vp_index(struct vmbus_channel *channel);

+/*
+ * Hyper-v presents FlexIOV devices on the PCIE.
+ * Those devices have no real PCI implementation in Hyper-V, and should be
+ * ignored and not presented to the PCI layer.
+ */
+static const guid_t vpci_ignore_instances[] = {
+ /*
+ * XStore Fastpath instance ID in VPCI introduced by FlexIOV
+ * {d4573da2-2caa-4711-a8f9-bbabf4ee9685}
+ */
+ GUID_INIT(0xd4573da2, 0x2caa, 0x4711, 0xa8, 0xf9,
+ 0xbb, 0xab, 0xf4, 0xee, 0x96, 0x85),
+};
+
const struct vmbus_device vmbus_devs[] = {
/* IDE */
{ .dev_type = HV_IDE,
@@ -487,6 +501,16 @@ void vmbus_free_channels(void)
}
}

+static bool ignore_pcie_device(guid_t *if_instance)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(vpci_ignore_instances); i++)
+ if (guid_equal(&vpci_ignore_instances[i], if_instance))
+ return true;
+ return false;
+}
+
/* Note: the function can run concurrently for primary/sub channels. */
static void vmbus_add_channel_work(struct work_struct *work)
{
@@ -958,6 +982,17 @@ static bool vmbus_is_valid_device(const guid_t *guid)
return false;
}

+static bool is_pcie_offer(struct vmbus_channel_offer_channel *offer)
+{
+ int i;
+
+ for (i = HV_IDE; i < HV_UNKNOWN; i++)
+ if (guid_equal(&offer->offer.if_type, &vmbus_devs[i].guid))
+ break;
+
+ return i == HV_PCIE;
+}
+
/*
* vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
*
@@ -1051,6 +1086,14 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
return;
}

+ /* Check to see if we should ignore this PCIe channel */
+ if (is_pcie_offer(offer) &&
+ ignore_pcie_device(&offer->offer.if_instance)) {
+ pr_info("Ignore instance %pUl over VPCI\n",
+ &offer->offer.if_instance);
+ return;
+ }
+
/* Allocate the channel object and save this offer. */
newchannel = alloc_channel();
if (!newchannel) {
--
1.8.3.1