vfio/pci: Revert nvlink removal uAPI breakage

Started by Alex Williamson on May 4, 2021 · 4 messages from 4 authors · Last reply May 5, 2021

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STALE2015d LANDED

Status: Landed in mainline as 77b8aeb9da04 on 2021-05-05.

open the first message on its own page

Message details and related content
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 <redacted>
Signed-off-by: Alex Williamson <redacted>
---

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,

Message details and related content
On Tue, 04 May 2021 09:52:02 -0600
Alex Williamson [off-list ref] wrote:
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 <redacted>
Signed-off-by: Alex Williamson <redacted>
---

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

 include/uapi/linux/vfio.h |   46 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 4 deletions(-)
I had already hacked up a QEMU patch that moved the definitions into
local headers, but this one is less of a hassle. (Code compiles fine
after doing a headers update.)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message details and related content
On Tue, 04 May 2021 09:52:02 -0600
Alex Williamson [off-list ref] wrote:
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 <redacted>
Signed-off-by: Alex Williamson <redacted>
---

Greg (Kurz), please double check this resolves the issue.  Thanks!
It does. Feel free to add:

Reviewed-by: Greg Kurz <redacted>

and

Tested-by: Greg Kurz <redacted>

Thanks for the quick fix.

Cheers,

--
Greg
quoted hunk
 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.

32 more quoted lines

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