On 1/21/21 10:32 AM, Thomas Huth wrote:
...snip...
+#include <asm/facility.h>
+
+static int share_pages(void *p, int count)
+{
+ int i = 0;
+
+ for (i = 0; i < count; i++, p += PAGE_SIZE)
+ if (uv_set_shared((unsigned long)p))
+ return i;
Just a matter of taste, but you could replace the "return i" here also
with a "break" since you're returning i below anyway.
right a single out point is always better.
+ return i;
+}
+
+static void unshare_pages(void *p, int count)
+{
+ int i;
+
+ for (i = count; i > 0; i--, p += PAGE_SIZE)
+ uv_remove_shared((unsigned long)p);
+}
+
+void *alloc_io_pages(int size, int flags)
I still think the naming or size parameter is confusing here. If I read
something like alloc_io_pages(), I'd expect a "num_pages" parameter. So
if you want to keep the "size" in bytes, I'd suggest to rename the
function to "alloc_io_mem" instead.
OK, I rename the function, allowing the user to keep a simple interface
without having to calculate the page order.
+{
+ int order = (size >> PAGE_SHIFT);
I think this is wrong. According to the description of alloc_pages_flag,
it allocates "1ull << order" pages.
So you likely want to do this instead here:
int order = get_order(size >> PAGE_SHIFT);
you are absolutely right.
+ void *p;
+ int n;
+
+ assert(size);
+
+ p = alloc_pages_flags(order, AREA_DMA31 | flags);
+ if (!p || !test_facility(158))
+ return p;
+
+ n = share_pages(p, 1 << order);
+ if (n == 1 << order)
+ return p;
+
+ unshare_pages(p, n);
+ free_pages(p);
+ return NULL;
+}
+
+void free_io_pages(void *p, int size)
+{
+ int order = size >> PAGE_SHIFT;
dito?
yes :(
+ assert(IS_ALIGNED((uintptr_t)p, PAGE_SIZE));
+
+ if (test_facility(158))
+ unshare_pages(p, 1 << order);
+ free_pages(p);
+}
diff --git a/lib/s390x/malloc_io.h b/lib/s390x/malloc_io.h
new file mode 100644
index 0000000..494dfe9
--- /dev/null
+++ b/lib/s390x/malloc_io.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
GPL-2.0-only please.
almmost... I use:
/* SPDX-License-Identifier: GPL-2.0-or-later */
as in other files updated by janosch if this is not a problem.
+/*
+ * I/O allocations
+ *
+ * Copyright (c) 2021 IBM Corp
+ *
+ * Authors:
+ * Pierre Morel <pmorel@xxxxxxxxxxxxx>
+ *
+ */
+#ifndef _S390X_MALLOC_IO_H_
+#define _S390X_MALLOC_IO_H_
+
+/*
+ * Allocates a page aligned page bound range of contiguous real or
+ * absolute memory in the DMA31 region large enough to contain size
+ * bytes.
+ * If Protected Virtualization facility is present, shares the pages
+ * with the host.
+ * If all the pages for the specified size cannot be reserved,
+ * the function rewinds the partial allocation and a NULL pointer
+ * is returned.
+ *
+ * @size: the minimal size allocated in byte.
+ * @flags: the flags used for the underlying page allocator.
+ *
+ * Errors:
+ * The allocation will assert the size parameter, will fail if the
+ * underlying page allocator fail or in the case of protected
+ * virtualisation if the sharing of the pages fails.
I think "virtualization" (with an z) is more common than "virtualisation".
OK
Thanks,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
