Adding upstream version 6.8.9.upstream/6.8.9

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 68 insertions, 0 deletions

diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index ada3868c02..c28f073c1d 100644
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/acpi.h>
 #include <linux/export.h>
+#include <linux/mm.h>
 
 #include <xen/hvc-console.h>
 
@@ -72,3 +73,70 @@ void __init mem_map_via_hcall(struct boot_params *boot_params_p)
 	}
 	boot_params_p->e820_entries = memmap.nr_entries;
 }
+
+/*
+ * Reserve e820 UNUSABLE regions to inflate the memory balloon.
+ *
+ * On PVH dom0 the host memory map is used, RAM regions available to dom0 are
+ * located as the same place as in the native memory map, but since dom0 gets
+ * less memory than the total amount of host RAM the ranges that can't be
+ * populated are converted from RAM -> UNUSABLE.  Use such regions (up to the
+ * ratio signaled in EXTRA_MEM_RATIO) in order to inflate the balloon driver at
+ * boot.  Doing so prevents the guest (even if just temporary) from using holes
+ * in the memory map in order to map grants or foreign addresses, and
+ * hopefully limits the risk of a clash with a device MMIO region.  Ideally the
+ * hypervisor should notify us which memory ranges are suitable for creating
+ * foreign mappings, but that's not yet implemented.
+ */
+void __init xen_reserve_extra_memory(struct boot_params *bootp)
+{
+	unsigned int i, ram_pages = 0, extra_pages;
+
+	for (i = 0; i < bootp->e820_entries; i++) {
+		struct boot_e820_entry *e = &bootp->e820_table[i];
+
+		if (e->type != E820_TYPE_RAM)
+			continue;
+		ram_pages += PFN_DOWN(e->addr + e->size) - PFN_UP(e->addr);
+	}
+
+	/* Max amount of extra memory. */
+	extra_pages = EXTRA_MEM_RATIO * ram_pages;
+
+	/*
+	 * Convert UNUSABLE ranges to RAM and reserve them for foreign mapping
+	 * purposes.
+	 */
+	for (i = 0; i < bootp->e820_entries && extra_pages; i++) {
+		struct boot_e820_entry *e = &bootp->e820_table[i];
+		unsigned long pages;
+
+		if (e->type != E820_TYPE_UNUSABLE)
+			continue;
+
+		pages = min(extra_pages,
+			PFN_DOWN(e->addr + e->size) - PFN_UP(e->addr));
+
+		if (pages != (PFN_DOWN(e->addr + e->size) - PFN_UP(e->addr))) {
+			struct boot_e820_entry *next;
+
+			if (bootp->e820_entries ==
+			    ARRAY_SIZE(bootp->e820_table))
+				/* No space left to split - skip region. */
+				continue;
+
+			/* Split entry. */
+			next = e + 1;
+			memmove(next, e,
+				(bootp->e820_entries - i) * sizeof(*e));
+			bootp->e820_entries++;
+			next->addr = PAGE_ALIGN(e->addr) + PFN_PHYS(pages);
+			e->size = next->addr - e->addr;
+			next->size -= e->size;
+		}
+		e->type = E820_TYPE_RAM;
+		extra_pages -= pages;
+
+		xen_add_extra_mem(PFN_UP(e->addr), pages);
+	}
+}