[UNIKRAFT/BALLOON v2 6/7] plat/xen/balloon: Xen balloon hypervisor calls implementation

[CezarCraciunoiu <cezar.craciunoiu@xxxxxxxxx>]

From: Cezar Craciunoiu <cezar.craciunoiu@xxxxxxxxx>

The Xen implementation just prepares the arguments for the functions and
drivers of the Xen hypervisor.

As Xen reserves and keeps separate memory zones for it's VM's, it is harder
to observe the behaviour of the balloon. To add to this, Xen already has
a working balloon that takes memory from the host, which makes things a bit
harder to test.

Signed-off-by: Cezar Craciunoiu <cezar.craciunoiu@xxxxxxxxx>
---
 plat/xen/Makefile.uk |   1 +
 plat/xen/balloon.c   | 135 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)
 create mode 100644 plat/xen/balloon.c

diff --git a/plat/xen/Makefile.uk b/plat/xen/Makefile.uk
index 2a8cdbf..76b7488 100644
--- a/plat/xen/Makefile.uk
+++ b/plat/xen/Makefile.uk
@@ -41,6 +41,7 @@ LIBXENPLAT_CINCLUDES-y         += 
-I$(UK_PLAT_COMMON_BASE)/include
 LIBXENPLAT_SRCS-y              += $(UK_PLAT_XEN_DEF_LDS)
 LIBXENPLAT_SRCS-y              += $(LIBXENPLAT_BASE)/hypervisor.c
 LIBXENPLAT_SRCS-y              += $(LIBXENPLAT_BASE)/memory.c
+LIBXENPLAT_SRCS-y              += $(LIBXENPLAT_BASE)/balloon.c
 LIBXENPLAT_SRCS-y              += $(LIBXENPLAT_BASE)/io.c
 LIBXENPLAT_SRCS-y              += $(UK_PLAT_COMMON_BASE)/lcpu.c|common
 LIBXENPLAT_SRCS-y              += $(UK_PLAT_COMMON_BASE)/memory.c|common
diff --git a/plat/xen/balloon.c b/plat/xen/balloon.c
new file mode 100644
index 0000000..7cc231f
--- /dev/null
+++ b/plat/xen/balloon.c
@@ -0,0 +1,135 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Authors: Cason Schindler & Jack Raney <cason.j.schindler@xxxxxxxxx>
+ *          Cezar Craciunoiu <cezar.craciunoiu@xxxxxxxxx>
+ *
+ * Copyright (c) 2019, The University of Texas at Austin. All rights reserved.
+ *               2020, University Politehnica of Bucharest. All rights 
reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
+ */
+#include <uk/plat/common/sections.h>
+
+#include <common/gnttab.h>
+#if (defined __X86_32__) || (defined __X86_64__)
+#include <xen-x86/setup.h>
+#include <xen-x86/mm_pv.h>
+#include <xen-x86/mm.h>
+#elif (defined __ARM_32__) || (defined __ARM_64__)
+#include <xen-arm/setup.h>
+#include <xen-arm/mm.h>
+#endif
+
+#include <xen/memory.h>
+#include <uk/plat/balloon.h>
+#include <common/hypervisor.h>
+
+#include <errno.h>
+#include <stddef.h>
+
+/**
+ * Set up and call Xen hypercall to ask for memory back from Xen.
+ */
+static int xenmem_reservation_increase(int count, xen_pfn_t *frames, int order)
+{
+       struct xen_memory_reservation res = {
+#if __XEN_INTERFACE_VERSION__ >= 0x00030209
+               .memflags = 0;
+#else
+               .address_bits = 0,
+#endif
+               .extent_order = order,
+               .domid        = DOMID_SELF
+       };
+
+       set_xen_guest_handle(res.extent_start, frames);
+       res.nr_extents = count;
+
+       /* Needs physical frame number */
+       return HYPERVISOR_memory_op(XENMEM_populate_physmap, &res);
+}
+
+/**
+ * Set up and call Xen hypercall to give memory to Xen.
+ */
+static int xenmem_reservation_decrease(int count, xen_pfn_t *frames, int order)
+{
+       struct xen_memory_reservation res = {
+#if __XEN_INTERFACE_VERSION__ >= 0x00030209
+               .mem_flags = 0,
+#else
+               .address_bits = 0,
+#endif
+               .extent_order = order,
+               .domid        = DOMID_SELF
+       };
+
+       set_xen_guest_handle(res.extent_start, frames);
+       res.nr_extents = count;
+
+       /* Needs guest frame number */
+       return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &res);
+}
+
+/**
+ * When we inflate we will be decreasing the memory available to the VM
+ * We will give the extent of extent order = order starting at va to the host.
+ */
+int ukplat_inflate(void *va, int order)
+{
+       xen_pfn_t pfn = virt_to_pfn(va);
+
+       if (va == NULL)
+               return -EINVAL;
+
+       return xenmem_reservation_decrease(1, &pfn, order);
+}
+
+/**
+ * When we deflate we will be increasing the memory available to the VM
+ * We will ask for 1 extent of extent order = order back from the host.
+ * It will map the extent to the address va.
+ */
+int ukplat_deflate(void *va, int order)
+{
+       /* Make sure we are sending the correct frame number. Should be a GFN */
+       xen_pfn_t pfn = virt_to_pfn(va);
+
+       if (va == NULL)
+               return -EINVAL;
+
+       return xenmem_reservation_increase(1, &pfn, order);
+}
+
+/**
+ * Sets behaviour for Xen.
+ */
+void ukplat_balloon_set(char *balloon_type)
+{
+       *balloon_type = 0;
+}
-- 
2.20.1