On 1/22/21 2:57 PM, Janosch Frank wrote:
On 1/22/21 2:27 PM, Pierre Morel wrote:
To centralize the memory allocation for I/O we define
the alloc_io_mem/free_io_mem functions which share the I/O
memory with the host in case the guest runs with
protected virtualization.
These functions allocate on a page integral granularity to
ensure a dedicated sharing of the allocated objects.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Acked-by: Janosch Frank <frankja@xxxxxxxxxx>
---
lib/s390x/malloc_io.c | 71 +++++++++++++++++++++++++++++++++++++++++++
lib/s390x/malloc_io.h | 45 +++++++++++++++++++++++++++
s390x/Makefile | 1 +
3 files changed, 117 insertions(+)
create mode 100644 lib/s390x/malloc_io.c
create mode 100644 lib/s390x/malloc_io.h
diff --git a/lib/s390x/malloc_io.c b/lib/s390x/malloc_io.c
new file mode 100644
index 0000000..b01222e
--- /dev/null
+++ b/lib/s390x/malloc_io.c
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * I/O page allocation
+ *
+ * Copyright (c) 2021 IBM Corp
+ *
+ * Authors:
+ * Pierre Morel <pmorel@xxxxxxxxxxxxx>
+ *
+ * Using this interface provide host access to the allocated pages in
+ * case the guest is a secure guest.
s/secure/protected/
OK
+ * This is needed for I/O buffers.
+ *
+ */
+#include <libcflat.h>
+#include <asm/page.h>
+#include <asm/uv.h>
+#include <malloc_io.h>
+#include <alloc_page.h>
+#include <asm/facility.h>
+#include <bitops.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))
+ break;
+ 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_mem(int size, int flags)
+{
+ int order = get_order(size >> PAGE_SHIFT);
+ void *p;
+ int n;
+
+ assert(size);
+
+ p = alloc_pages_flags(order, AREA_DMA31 | flags);
Pardon my lack of IO knowledge but do we also need to restrict the data
to below 2g or only the IO control structures?
Not that it currently matters much for a unit test with 256mb of memory...
it depends, if you know how work most scatter-gather it is easy:
INSTR-> ORB -> CCW -> DATA
first level metadata: yes
- Intruction point with 31bit to ORB
- ORB point with 31b to CCW
- CCW point with 31b to data
first level of data, the one pointed by the CCW: yes
This is all what is used in this patch.
To be developed in the future:
INSTR-> ORB -> CCW -> [M]IDA -> DATA
second level metadata:
they are pointed to by CCW...
- IDA : yes
- MIDA: yes
second level data (indirect buffering)
- IDA format 1: 31b address: yes
- IDA format 2: 64b address: no
- MIDA : 64b address: no
Or to sum up only data accessed with indirect addressing by IDA format 2
and MIDA can be anywhere.
+ 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_mem(void *p, int size)
+{
+ int order = get_order(size >> PAGE_SHIFT);
+
+ 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..cc5fad7
--- /dev/null
+++ b/lib/s390x/malloc_io.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * 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 Virtualisation facility is present, shares the pages
s/Virtualisation/Virtualization/
But I can fix this and the nitpick above up when picking.
:) Thomas made me change this in the last round.
As far as I know "z" is used in the uS ans "s" in England (and France).
regards,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
