drm/amdgpu: Surface svm_default_granularity, a RW module parameter

Enables users to update SVM's default granularity, used in
buffer migration and handling of recoverable page faults.
Param value is set in terms of log(numPages(buffer)),
e.g. 9 for a 2 MIB buffer

Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index e095572458cde4524e767e26e7eaae7fafb4fd87..dcd59040c449d5c5d922ee92e455e6bf33ff1b44 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -237,6 +237,7 @@ extern int sched_policy;
 extern bool debug_evictions;
 extern bool no_system_mem_limit;
 extern int halt_if_hws_hang;
+extern uint amdgpu_svm_default_granularity;
 #else
 static const int __maybe_unused sched_policy = KFD_SCHED_POLICY_HWS;
 static const bool __maybe_unused debug_evictions; /* = false */

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 8dee7c62c801da1f030df40f3a6b3b24d433c441..86cff30d5c4e99f9525c0a4445fbd76c7612b07d 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -169,6 +169,16 @@ uint amdgpu_sdma_phase_quantum = 32;
 char *amdgpu_disable_cu;
 char *amdgpu_virtual_display;
 bool enforce_isolation;
+
+/* Specifies the default granularity for SVM, used in buffer
+ * migration and restoration of backing memory when handling
+ * recoverable page faults.
+ *
+ * The value is given as log(numPages(buffer)); for a 2 MiB
+ * buffer it computes to be 9
+ */
+uint amdgpu_svm_default_granularity = 9;
+
 /*
  * OverDrive(bit 14) disabled by default
  * GFX DCS(bit 19) disabled by default
@@ -320,6 +330,13 @@ module_param_named(pcie_gen2, amdgpu_pcie_gen2, int, 0444);
 MODULE_PARM_DESC(msi, "MSI support (1 = enable, 0 = disable, -1 = auto)");
 module_param_named(msi, amdgpu_msi, int, 0444);
 
+/**
+ * DOC: svm_default_granularity (uint)
+ * Used in buffer migration and handling of recoverable page faults
+ */
+MODULE_PARM_DESC(svm_default_granularity, "SVM's default granularity in log(2^Pages), default 9 = 2^9 = 2 MiB");
+module_param_named(svm_default_granularity, amdgpu_svm_default_granularity, uint, 0644);
+
 /**
  * DOC: lockup_timeout (string)
  * Set GPU scheduler timeout value in ms.

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index 9ae9abc6eb433466018df0762e62241dc09f01fb..d6530febabad7fa3f02e5b07f1c9a1794d73cf33 100644 (file)
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -868,6 +868,12 @@ struct svm_range_list {
        struct task_struct              *faulting_task;
        /* check point ts decides if page fault recovery need be dropped */
        uint64_t                        checkpoint_ts[MAX_GPU_INSTANCE];
+
+       /* Default granularity to use in buffer migration
+        * and restoration of backing memory while handling
+        * recoverable page faults
+        */
+       uint8_t default_granularity;
 };
 
 /* Process data */

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 40c94c4cdd96d2c93b14914c1d8c7bd7510ea69e..04e746923697459956af019b2d1bbd0ab9fdf4a8 100644 (file)
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -309,12 +309,13 @@ static void svm_range_free(struct svm_range *prange, bool do_unmap)
 }
 
 static void
-svm_range_set_default_attributes(int32_t *location, int32_t *prefetch_loc,
-                                uint8_t *granularity, uint32_t *flags)
+svm_range_set_default_attributes(struct svm_range_list *svms, int32_t *location,
+                                int32_t *prefetch_loc, uint8_t *granularity,
+                                uint32_t *flags)
 {
        *location = KFD_IOCTL_SVM_LOCATION_UNDEFINED;
        *prefetch_loc = KFD_IOCTL_SVM_LOCATION_UNDEFINED;
-       *granularity = 9;
+       *granularity = svms->default_granularity;
        *flags =
                KFD_IOCTL_SVM_FLAG_HOST_ACCESS | KFD_IOCTL_SVM_FLAG_COHERENT;
 }
@@ -358,7 +359,7 @@ svm_range *svm_range_new(struct svm_range_list *svms, uint64_t start,
                bitmap_copy(prange->bitmap_access, svms->bitmap_supported,
                            MAX_GPU_INSTANCE);
 
-       svm_range_set_default_attributes(&prange->preferred_loc,
+       svm_range_set_default_attributes(svms, &prange->preferred_loc,
                                         &prange->prefetch_loc,
                                         &prange->granularity, &prange->flags);
 
@@ -2703,9 +2704,10 @@ svm_range_get_range_boundaries(struct kfd_process *p, int64_t addr,
        *is_heap_stack = vma_is_initial_heap(vma) || vma_is_initial_stack(vma);
 
        start_limit = max(vma->vm_start >> PAGE_SHIFT,
-                     (unsigned long)ALIGN_DOWN(addr, 2UL << 8));
+                     (unsigned long)ALIGN_DOWN(addr, 1UL << p->svms.default_granularity));
        end_limit = min(vma->vm_end >> PAGE_SHIFT,
-                   (unsigned long)ALIGN(addr + 1, 2UL << 8));
+                   (unsigned long)ALIGN(addr + 1, 1UL << p->svms.default_granularity));
+
        /* First range that starts after the fault address */
        node = interval_tree_iter_first(&p->svms.objects, addr + 1, ULONG_MAX);
        if (node) {
@@ -3249,6 +3251,12 @@ int svm_range_list_init(struct kfd_process *p)
                if (KFD_IS_SVM_API_SUPPORTED(p->pdds[i]->dev->adev))
                        bitmap_set(svms->bitmap_supported, i, 1);
 
+        /* Value of default granularity cannot exceed 0x1B, the
+         * number of pages supported by a 4-level paging table
+         */
+       svms->default_granularity = min_t(u8, amdgpu_svm_default_granularity, 0x1B);
+       pr_debug("Default SVM Granularity to use: %d\n", svms->default_granularity);
+
        return 0;
 }
 
@@ -3776,7 +3784,7 @@ svm_range_get_attr(struct kfd_process *p, struct mm_struct *mm,
        node = interval_tree_iter_first(&svms->objects, start, last);
        if (!node) {
                pr_debug("range attrs not found return default values\n");
-               svm_range_set_default_attributes(&location, &prefetch_loc,
+               svm_range_set_default_attributes(svms, &location, &prefetch_loc,
                                                 &granularity, &flags_and);
                flags_or = flags_and;
                if (p->xnack_enabled)