drm/nouveau/compote: add page fault handler

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>

1 files changed, 122 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/compote/compote-pfault.c b/drivers/gpu/drm/nouveau/compote/compote-pfault.c
index f46c13fad44d..41c4becceb53 100644
--- a/drivers/gpu/drm/nouveau/compote/compote-pfault.c
+++ b/drivers/gpu/drm/nouveau/compote/compote-pfault.c
@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
+#include <linux/hmm.h>
 #include <linux/fs.h>
 #include <uapi/drm/compote-uapi.h>
 #include "compote.h"
@@ -82,10 +83,130 @@ static inline void compote_file_pfault_read(struct compote_file *cfile,
 	pfault->info = nvif_rd32(&cfile->nvpfault_buffer, index + 0x1c);
 }
 
+static bool compote_nvkm_vma_unref(struct nvkm_vma *nvvma)
+{
+	mutex_lock(&nvvma->mutex);
+	if ((--nvvma->refcount) <= 0) {
+		nvkm_vm_put(nvvma);
+		kfree(nvvma->dmas);
+		kfree(nvvma->pfns);
+		mutex_unlock(&nvvma->mutex);
+		kfree(nvvma);
+		return false;
+	}
+	mutex_unlock(&nvvma->mutex);
+	return true;
+}
+
 static int compote_pfault_handler(struct compote_file *cfile,
 				  const struct compote_pfault *pfault)
 {
-	return -EINVAL;
+	bool write = compote_pfault_access(pfault) == 1;
+	struct mm_struct *mm = cfile->mm;
+	struct vm_area_struct *vma;
+	unsigned long addr, end;
+	struct hmm_range range;
+	struct nvkm_vma *nvvma;
+	struct nvkm_vm *nvvm;
+	uint32_t access;
+	int ret;
+
+	addr = pfault->addr;
+	end = addr + PAGE_SIZE;
+
+again:
+	down_read(&mm->mmap_sem);
+	vma = find_vma_intersection(mm, addr, end);
+	if (!vma) {
+		up_read(&mm->mmap_sem);
+		return -EFAULT;
+	}
+
+	if (!(vma->vm_flags & VM_READ)) {
+		up_read(&mm->mmap_sem);
+		return -EFAULT;
+	}
+	access = NV_MEM_ACCESS_RO;
+	if (write && !(vma->vm_flags & VM_WRITE)) {
+		up_read(&mm->mmap_sem);
+		return -EFAULT;
+	} else {
+		access |= NV_MEM_ACCESS_WO;
+	}
+
+	nvvm = cfile->nvclient.vm;
+	access = NV_MEM_ACCESS_RW;
+	nvvma = nvkm_vm_find(nvvm, addr, end);
+	if (nvvma == NULL) {
+		nvvma = kzalloc(sizeof(*nvvma), GFP_KERNEL);
+		if (nvvma == NULL) {
+			ret = -ENOMEM;
+			goto error;
+		}
+		mutex_init(&nvvma->mutex);
+		nvvma->dmas = kzalloc(sizeof(dma_addr_t), GFP_KERNEL);
+		if (nvvma->dmas == NULL) {
+			kfree(nvvma);
+			ret = -ENOMEM;
+			goto error;
+		}
+		nvvma->pfns = kzalloc(sizeof(long), GFP_KERNEL);
+		if (nvvma->pfns == NULL) {
+			kfree(nvvma->dmas);
+			kfree(nvvma);
+			ret = -ENOMEM;
+			goto error;
+		}
+		nvvma->refcount = 1;
+		ret = nvkm_vm_get_fix(nvvm, addr, PAGE_SIZE, 12, access, nvvma);
+		if (ret) {
+			compote_nvkm_vma_unref(nvvma);
+			goto error;
+		}
+	}
+
+	if (!nvvma || !nvvma->pfns) {
+		ret = -EINVAL;
+		goto error;
+	}
+
+	if ((nvvma->pfns[0] & HMM_PFN_VALID)) {
+		if (!compote_nvkm_vma_unref(nvvma)) {
+			up_read(&mm->mmap_sem);
+			goto again;
+		}
+		nvvma->pfns[0] = 0;
+	}
+	ret = hmm_vma_fault(vma, &range, addr, end, nvvma->pfns, write, false);
+	if (ret == -EAGAIN) {
+		compote_nvkm_vma_unref(nvvma);
+		up_read(&mm->mmap_sem);
+		goto again;
+	}
+	if (ret) {
+		compote_nvkm_vma_unref(nvvma);
+		goto error;
+	}
+
+	mutex_lock(&nvvma->mutex);
+	if (!hmm_vma_range_done(vma, &range)) {
+		nvvma->pfns[0] = 0;
+		mutex_unlock(&nvvma->mutex);
+		up_read(&mm->mmap_sem);
+		goto again;
+	}
+	if (!(nvvma->pfns[0] & HMM_PFN_VALID)) {
+		mutex_unlock(&nvvma->mutex);
+		up_read(&mm->mmap_sem);
+		goto again;
+	}
+	nvvma->refcount++;
+	ret = compote_nvkm_vma_map(cfile, nvvma, addr, PAGE_SIZE);
+	mutex_unlock(&nvvma->mutex);
+
+error:
+	up_read(&mm->mmap_sem);
+	return ret;
 }
 
 static int compote_file_pfault_process(struct nvif_notify *notify)