xen/balloon: Share common memory reservation routines
Memory {increase|decrease}_reservation and VA mappings update/reset
code used in balloon driver can be made common, so other drivers can
also re-use the same functionality without open-coding.
Create a dedicated file for the shared code and export corresponding
symbols for other kernel modules.
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
diff --git a/drivers/xen/mem-reservation.c b/drivers/xen/mem-reservation.c
new file mode 100644
index 0000000..084799c
--- /dev/null
+++ b/drivers/xen/mem-reservation.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/******************************************************************************
+ * Xen memory reservation utilities.
+ *
+ * Copyright (c) 2003, B Dragovic
+ * Copyright (c) 2003-2004, M Williamson, K Fraser
+ * Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
+ * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
+ */
+
+#include <asm/xen/hypercall.h>
+
+#include <xen/interface/memory.h>
+#include <xen/mem-reservation.h>
+
+/*
+ * Use one extent per PAGE_SIZE to avoid to break down the page into
+ * multiple frame.
+ */
+#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
+
+#ifdef CONFIG_XEN_HAVE_PVMMU
+void __xenmem_reservation_va_mapping_update(unsigned long count,
+ struct page **pages,
+ xen_pfn_t *frames)
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ struct page *page = pages[i];
+ unsigned long pfn = page_to_pfn(page);
+
+ BUG_ON(!page);
+
+ /*
+ * We don't support PV MMU when Linux and Xen is using
+ * different page granularity.
+ */
+ BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
+
+ set_phys_to_machine(pfn, frames[i]);
+
+ /* Link back into the page tables if not highmem. */
+ if (!PageHighMem(page)) {
+ int ret;
+
+ ret = HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << PAGE_SHIFT),
+ mfn_pte(frames[i], PAGE_KERNEL),
+ 0);
+ BUG_ON(ret);
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_update);
+
+void __xenmem_reservation_va_mapping_reset(unsigned long count,
+ struct page **pages)
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ struct page *page = pages[i];
+ unsigned long pfn = page_to_pfn(page);
+
+ /*
+ * We don't support PV MMU when Linux and Xen are using
+ * different page granularity.
+ */
+ BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
+
+ if (!PageHighMem(page)) {
+ int ret;
+
+ ret = HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << PAGE_SHIFT),
+ __pte_ma(0), 0);
+ BUG_ON(ret);
+ }
+ __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+ }
+}
+EXPORT_SYMBOL_GPL(__xenmem_reservation_va_mapping_reset);
+#endif /* CONFIG_XEN_HAVE_PVMMU */
+
+/* @frames is an array of PFNs */
+int xenmem_reservation_increase(int count, xen_pfn_t *frames)
+{
+ struct xen_memory_reservation reservation = {
+ .address_bits = 0,
+ .extent_order = EXTENT_ORDER,
+ .domid = DOMID_SELF
+ };
+
+ /* XENMEM_populate_physmap requires a PFN based on Xen granularity. */
+ set_xen_guest_handle(reservation.extent_start, frames);
+ reservation.nr_extents = count;
+ return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+}
+EXPORT_SYMBOL_GPL(xenmem_reservation_increase);
+
+/* @frames is an array of GFNs */
+int xenmem_reservation_decrease(int count, xen_pfn_t *frames)
+{
+ struct xen_memory_reservation reservation = {
+ .address_bits = 0,
+ .extent_order = EXTENT_ORDER,
+ .domid = DOMID_SELF
+ };
+
+ /* XENMEM_decrease_reservation requires a GFN */
+ set_xen_guest_handle(reservation.extent_start, frames);
+ reservation.nr_extents = count;
+ return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
+}
+EXPORT_SYMBOL_GPL(xenmem_reservation_decrease);
