[PATCH] vfio/pci: Revert nvlink removal uAPI breakage

From: Alex Williamson
Date: Tue May 04 2021 - 11:52:17 EST


Revert the uAPI changes from the below commit with notice that these
regions and capabilities are no longer provided.

Fixes: b392a1989170 ("vfio/pci: remove vfio_pci_nvlink2")
Reported-by: Greg Kurz <groug@xxxxxxxx>
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---

Greg (Kurz), please double check this resolves the issue. Thanks!

include/uapi/linux/vfio.h | 46 +++++++++++++++++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 34b1f53a3901..ef33ea002b0b 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -333,10 +333,21 @@ struct vfio_region_info_cap_type {
#define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG (3)

/* 10de vendor PCI sub-types */
-/* subtype 1 was VFIO_REGION_SUBTYPE_NVIDIA_NVLINK2_RAM, don't use */
+/*
+ * NVIDIA GPU NVlink2 RAM is coherent RAM mapped onto the host address space.
+ *
+ * Deprecated, region no longer provided
+ */
+#define VFIO_REGION_SUBTYPE_NVIDIA_NVLINK2_RAM (1)

/* 1014 vendor PCI sub-types */
-/* subtype 1 was VFIO_REGION_SUBTYPE_IBM_NVLINK2_ATSD, don't use */
+/*
+ * IBM NPU NVlink2 ATSD (Address Translation Shootdown) register of NPU
+ * to do TLB invalidation on a GPU.
+ *
+ * Deprecated, region no longer provided
+ */
+#define VFIO_REGION_SUBTYPE_IBM_NVLINK2_ATSD (1)

/* sub-types for VFIO_REGION_TYPE_GFX */
#define VFIO_REGION_SUBTYPE_GFX_EDID (1)
@@ -630,9 +641,36 @@ struct vfio_device_migration_info {
*/
#define VFIO_REGION_INFO_CAP_MSIX_MAPPABLE 3

-/* subtype 4 was VFIO_REGION_INFO_CAP_NVLINK2_SSATGT, don't use */
+/*
+ * Capability with compressed real address (aka SSA - small system address)
+ * where GPU RAM is mapped on a system bus. Used by a GPU for DMA routing
+ * and by the userspace to associate a NVLink bridge with a GPU.
+ *
+ * Deprecated, capability no longer provided
+ */
+#define VFIO_REGION_INFO_CAP_NVLINK2_SSATGT 4
+
+struct vfio_region_info_cap_nvlink2_ssatgt {
+ struct vfio_info_cap_header header;
+ __u64 tgt;
+};

-/* subtype 5 was VFIO_REGION_INFO_CAP_NVLINK2_LNKSPD, don't use */
+/*
+ * Capability with an NVLink link speed. The value is read by
+ * the NVlink2 bridge driver from the bridge's "ibm,nvlink-speed"
+ * property in the device tree. The value is fixed in the hardware
+ * and failing to provide the correct value results in the link
+ * not working with no indication from the driver why.
+ *
+ * Deprecated, capability no longer provided
+ */
+#define VFIO_REGION_INFO_CAP_NVLINK2_LNKSPD 5
+
+struct vfio_region_info_cap_nvlink2_lnkspd {
+ struct vfio_info_cap_header header;
+ __u32 link_speed;
+ __u32 __pad;
+};

/**
* VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,