From 3e230516034d29e84ca023fe95e284af5cd5a065 Mon Sep 17 00:00:00 2001
From: Aleksey Smolenchuk <lxe@lxe.co>
Date: Tue, 21 Oct 2025 09:51:30 -0700
Subject: [PATCH] nvidia-uvm: Add support for kernel 6.18 get_dev_pagemap API
 change

The get_dev_pagemap() function signature changed in Linux kernel 6.18
to take only a single pfn parameter, removing the lock parameter.

This commit adds a conftest check to detect the API version and
conditionally calls get_dev_pagemap() with the appropriate number
of arguments.
---
 kernel-open/conftest.sh                        | 18 ++++++++++++++++++
 kernel-open/nvidia-uvm/nvidia-uvm.Kbuild       |  1 +
 .../nvidia-uvm/uvm_va_range_device_p2p.c       |  4 ++++
 3 files changed, 23 insertions(+)

diff --git a/kernel-open/conftest.sh b/kernel-open/conftest.sh
index cfa387129..731ed18bd 100755
--- a/kernel-open/conftest.sh
+++ b/kernel-open/conftest.sh
@@ -4871,6 +4871,24 @@ compile_test() {
             compile_check_conftest "$CODE" "NV_MEMORY_DEVICE_COHERENT_PRESENT" "" "types"
         ;;
 
+        get_dev_pagemap_single_arg)
+            #
+            # Determine if get_dev_pagemap() takes single argument.
+            #
+            # The get_dev_pagemap() function was updated to take only pfn argument
+            # and the lock parameter was removed in kernel v6.18.
+            #
+            CODE="
+            #include <linux/mm.h>
+            #include <linux/memremap.h>
+            void conftest_get_dev_pagemap(void) {
+                struct dev_pagemap *pgmap;
+                unsigned long pfn = 0;
+                pgmap = get_dev_pagemap(pfn);
+            }"
+
+            compile_check_conftest "$CODE" "NV_GET_DEV_PAGEMAP_SINGLE_ARG" "" "types"
+        ;;
 
         # When adding a new conftest entry, please use the correct format for
         # specifying the relevant upstream Linux kernel commit.  Please
diff --git a/kernel-open/nvidia-uvm/nvidia-uvm.Kbuild b/kernel-open/nvidia-uvm/nvidia-uvm.Kbuild
index 485f0f85d..db5e160ef 100644
--- a/kernel-open/nvidia-uvm/nvidia-uvm.Kbuild
+++ b/kernel-open/nvidia-uvm/nvidia-uvm.Kbuild
@@ -61,6 +61,7 @@ NV_CONFTEST_TYPE_COMPILE_TESTS += mmu_notifier_ops_arch_invalidate_secondary_tlb
 NV_CONFTEST_TYPE_COMPILE_TESTS += migrate_vma_added_flags
 NV_CONFTEST_TYPE_COMPILE_TESTS += migrate_device_range
 NV_CONFTEST_TYPE_COMPILE_TESTS += handle_mm_fault_has_pt_regs_arg
+NV_CONFTEST_TYPE_COMPILE_TESTS += get_dev_pagemap_single_arg
 NV_CONFTEST_TYPE_COMPILE_TESTS += mempolicy_has_unified_nodes
 NV_CONFTEST_TYPE_COMPILE_TESTS += mempolicy_has_home_node
 NV_CONFTEST_TYPE_COMPILE_TESTS += mpol_preferred_many_present
diff --git a/kernel-open/nvidia-uvm/uvm_va_range_device_p2p.c b/kernel-open/nvidia-uvm/uvm_va_range_device_p2p.c
index 8a5c87bd3..27bb087c5 100644
--- a/kernel-open/nvidia-uvm/uvm_va_range_device_p2p.c
+++ b/kernel-open/nvidia-uvm/uvm_va_range_device_p2p.c
@@ -360,7 +360,11 @@ static NV_STATUS alloc_device_p2p_mem(uvm_gpu_t *gpu,
         // a reference to them, so take one now if using DEVICE_COHERENT pages.
         if (gpu->parent->cdmm_enabled) {
             get_page(page);
+#if defined(NV_GET_DEV_PAGEMAP_SINGLE_ARG)
+            get_dev_pagemap(page_to_pfn(page));
+#else
             get_dev_pagemap(page_to_pfn(page), NULL);
+#endif
         }
 #else
         // CDMM P2PDMA will never be enabled for this case