[PATCH RFC v2 24/50] samples/kvm: Remove MPS_SETUP support from sample provider

[Ackerley Tng via B4 Relay <devnull+ackerleytng.google.com@kernel.org>]

From: Ackerley Tng <ackerleytng@google.com>

MPS_SETUP is a subset of the functionality provided by MPS_NEW_CHILD.
A single file covering the entire region can be created by carving out
the full range with MPS_NEW_CHILD.

Retain MPS_NEW_CHILD as it enables testing alternative provider
functionality when there are separate sub-pools of memory carved out
from the root.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
 samples/kvm/mem_provider_sample.c | 72 ---------------------------------------
 samples/kvm/mem_provider_sample.h | 29 ++--------------
 2 files changed, 3 insertions(+), 98 deletions(-)

diff --git a/samples/kvm/mem_provider_sample.c b/samples/kvm/mem_provider_sample.c
index 4e8f306ba1154..abb8e35cd5357 100644
--- a/samples/kvm/mem_provider_sample.c
+++ b/samples/kvm/mem_provider_sample.c
@@ -61,7 +61,6 @@ struct mps_info {
 	unsigned long base_pfn;
 	unsigned long npages;
 	struct page *cma_pages;		/* from alloc_contig_pages(), or NULL */
-	bool fixed;			/* a SETUP file over addr=/len= */
 	bool mmap_capable;
 	bool fixed_wb;			/* holds a ref on the fixed-region WB alias */
 
@@ -87,11 +86,6 @@ static struct mps_root {
 	struct page *cma_pages;
 	unsigned long *allocated;	/* pages allocated to a child */
 	struct list_head children;
-	/*
-	 * The addr=/len= region is used either by one SETUP file or by the
-	 * root, never by both, so that its frames have one owner.
-	 */
-	bool fixed_setup;
 	/* Files over the fixed region that may be mapped into userspace. */
 	unsigned int fixed_wb_users;
 } mps_root;
@@ -289,8 +283,6 @@ static int mps_file_release(struct inode *inode, struct file *file)
 	}
 	if (addr && len && !info->cma_pages) {
 		mutex_lock(&mps_root.lock);
-		if (info->fixed)
-			mps_root.fixed_setup = false;
 		if (info->fixed_wb)
 			mps_fixed_wb_put();
 		mutex_unlock(&mps_root.lock);
@@ -373,66 +365,6 @@ static struct page *mps_alloc_region(unsigned long npages)
 	return pages;
 }
 
-static long mps_ctl_setup(void __user *uarg)
-{
-	struct mps_setup setup;
-	unsigned long base_pfn, npages;
-	struct page *pages = NULL;
-	struct mps_info *info;
-	struct file *file;
-	int fd;
-
-	if (copy_from_user(&setup, uarg, sizeof(setup)))
-		return -EFAULT;
-	if ((setup.flags & ~MPS_FLAG_MMAP_CAPABLE) || setup.pad)
-		return -EINVAL;
-
-	if (addr && len) {
-		/* The fixed region has one owner: this file or the root. */
-		mutex_lock(&mps_root.lock);
-		if (mps_root.fixed_setup || mps_root.npages) {
-			mutex_unlock(&mps_root.lock);
-			return -EBUSY;
-		}
-		fd = mps_new_file(addr >> PAGE_SHIFT, len >> PAGE_SHIFT,
-				  setup.flags, &info, &file);
-		if (fd >= 0 && mps_over_fixed_mappable(info)) {
-			if (mps_fixed_wb_get()) {
-				put_unused_fd(fd);
-				fput(file);
-				fd = -ENOMEM;
-			} else {
-				info->fixed_wb = true;
-			}
-		}
-		if (fd >= 0) {
-			info->fixed = true;
-			mps_root.fixed_setup = true;
-		}
-		mutex_unlock(&mps_root.lock);
-		if (fd >= 0)
-			fd_install(fd, file);
-		return fd;
-	}
-
-	if (!setup.size || !PAGE_ALIGNED(setup.size))
-		return -EINVAL;
-	npages = setup.size >> PAGE_SHIFT;
-	pages = mps_alloc_region(npages);
-	if (!pages)
-		return -ENOMEM;
-	base_pfn = page_to_pfn(pages);
-
-	fd = mps_new_file(base_pfn, npages, setup.flags, &info, &file);
-	if (fd < 0) {
-		free_contig_range(base_pfn, npages);
-		return fd;
-	}
-	info->cma_pages = pages;
-	fd_install(fd, file);
-	return fd;
-}
-
 /* ---- Root and children -------------------------------------------------- */
 
 /* Create the root on the first NEW_CHILD, from addr=/len= or of @size. */
@@ -446,8 +378,6 @@ static int mps_root_ensure(u64 size)
 		return 0;
 
 	if (addr && len) {
-		if (mps_root.fixed_setup)
-			return -EBUSY;
 		mps_root.base_pfn = addr >> PAGE_SHIFT;
 		npages = len >> PAGE_SHIFT;
 	} else {
@@ -596,8 +526,6 @@ static long mps_ctl_ioctl(struct file *file, unsigned int cmd,
 	void __user *uarg = (void __user *)arg;
 
 	switch (cmd) {
-	case MPS_SETUP:
-		return mps_ctl_setup(uarg);
 	case MPS_NEW_CHILD:
 		return mps_ctl_new_child(uarg);
 	case MPS_CTL_SET_PRESENT:
diff --git a/samples/kvm/mem_provider_sample.h b/samples/kvm/mem_provider_sample.h
index 1afea136328f5..3b0928b6478ca 100644
--- a/samples/kvm/mem_provider_sample.h
+++ b/samples/kvm/mem_provider_sample.h
@@ -14,38 +14,17 @@
  * the ioctls below make.
  */
 
-/* Flags for struct mps_setup and struct mps_new_child */
+/* Flags for struct mps_new_child */
 /* The host may map the pages; otherwise they are NO_USER_MAP */
 #define MPS_FLAG_MMAP_CAPABLE	(1u << 0)
 
-/*
- * ioctl on /dev/mem_provider_sample: create a provider fd.
- *
- * If the module was loaded with addr= and len=, the fd covers that fixed
- * range, which has no struct page, and @size is ignored.  The fixed range
- * then has one owner.  SETUP fails with -EBUSY while a SETUP file uses it,
- * or once the first MPS_NEW_CHILD has made it the root of the children, which
- * lasts until the module is unloaded.  MPS_NEW_CHILD fails with -EBUSY while
- * a SETUP file uses it.  Otherwise the fd covers @size bytes from
- * alloc_contig_pages().
- */
-struct mps_setup {
-	__u32 flags;	/* MPS_FLAG_* */
-	__u32 pad;
-	__u64 size;	/* bytes, page aligned */
-};
-
 #define MPS_IOCTL_BASE		'P'
-#define MPS_SETUP \
-	_IOW(MPS_IOCTL_BASE, 1, struct mps_setup)
 
 /*
  * ---- A tree of owners --------------------------------------------------
  *
  * The control device owns one region, the root.  NEW_CHILD carves part of
- * it into a new provider fd for one VM.  The owner can MOVE pages between
- * children, DONATE pages to the root, so that no child has them, and
- * RECLAIM them.  Each change revokes the range, so KVM and iommufd follow.
+ * it into a new provider fd for one VM.
  *
  * The owner changes a child's pages through the control device
  * (CTL_SET_PRESENT).  A child fd is read-only to its holder: a VMM can
@@ -54,9 +33,7 @@ struct mps_setup {
 
 /*
  * ioctl on /dev/mem_provider_sample: carve [@offset, @offset + @len) of the
- * root into a new child fd.  The child gets every page of the range that no
- * other child has and that is not donated.  Ranges of children may overlap,
- * which is how a page can MOVE between them.  Returns the child fd.
+ * root into a new child fd. Returns the child fd.
  */
 struct mps_new_child {
 	__u32 flags;	/* MPS_FLAG_* */

-- 
2.56.0.257.gf7497c7d27-goog