---
Changes in v3:
* Use PFN_PHYS
* Replace kzalloc with kmalloc
* Declare arch_xen_balloon_init prototype in balloon.h
* Rename resources (s/memory/RAM/)
* Clarify (I think) comment when populating hostmem_resource
* Print open-ended interval on insert_resource() error
* Constify declaration of struct e820_entry *entry
arch/x86/xen/enlighten.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++
arch/x86/xen/setup.c | 6 ++--
drivers/xen/balloon.c | 65 ++++++++++++++++++++++++++++++++------
include/xen/balloon.h | 5 +++
4 files changed, 144 insertions(+), 13 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d669e9d..c9081c6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1,8 +1,12 @@
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+#include <linux/bootmem.h>
+#endif
#include <linux/cpu.h>
#include <linux/kexec.h>
#include <xen/features.h>
#include <xen/page.h>
+#include <xen/interface/memory.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
@@ -331,3 +335,80 @@ void xen_arch_unregister_cpu(int num)
}
EXPORT_SYMBOL(xen_arch_unregister_cpu);
#endif
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+void __init arch_xen_balloon_init(struct resource *hostmem_resource)
+{
+ struct xen_memory_map memmap;
+ int rc;
+ unsigned int i, last_guest_ram;
+ phys_addr_t max_addr = PFN_PHYS(max_pfn);
+ struct e820_table *xen_e820_table;
+ const struct e820_entry *entry;
+ struct resource *res;
+
+ if (!xen_initial_domain())
+ return;
+
+ xen_e820_table = kmalloc(sizeof(*xen_e820_table), GFP_KERNEL);
+ if (!xen_e820_table)
+ return;
+
+ memmap.nr_entries = ARRAY_SIZE(xen_e820_table->entries);
+ set_xen_guest_handle(memmap.buffer, xen_e820_table->entries);
+ rc = HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap);
+ if (rc) {
+ pr_warn("%s: Can't read host e820 (%d)\n", __func__, rc);
+ goto out;
+ }
+
+ last_guest_ram = 0;
+ for (i = 0; i < memmap.nr_entries; i++) {
+ if (xen_e820_table->entries[i].addr >= max_addr)
+ break;
+ if (xen_e820_table->entries[i].type == E820_TYPE_RAM)
+ last_guest_ram = i;
+ }
+
+ entry = &xen_e820_table->entries[last_guest_ram];
+ if (max_addr >= entry->addr + entry->size)
+ goto out; /* No unallocated host RAM. */
+
+ hostmem_resource->start = max_addr;
+ hostmem_resource->end = entry->addr + entry->size;
+
+ /*
+ * Mark non-RAM regions between the end of dom0 RAM and end of host RAM
+ * as unavailable. The rest of that region can be used for hotplug-based
+ * ballooning.
+ */
+ for (; i < memmap.nr_entries; i++) {
+ entry = &xen_e820_table->entries[i];
+
+ if (entry->type == E820_TYPE_RAM)
+ continue;
+
+ if (entry->addr >= hostmem_resource->end)
+ break;
+
+ res = kzalloc(sizeof(*res), GFP_KERNEL);
+ if (!res)
+ goto out;
+
+ res->name = "Unavailable host RAM";
+ res->start = entry->addr;
+ res->end = (entry->addr + entry->size < hostmem_resource->end) ?
+ entry->addr + entry->size : hostmem_resource->end;
+ rc = insert_resource(hostmem_resource, res);
+ if (rc) {
+ pr_warn("%s: Can't insert [%llx - %llx) (%d)\n",
+ __func__, res->start, res->end, rc);
+ kfree(res);
+ goto out;
+ }
+ }
+
+ out:
+ kfree(xen_e820_table);
+}
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index c114ca7..6e0d208 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -808,7 +808,6 @@ char * __init xen_memory_setup(void)
addr = xen_e820_table.entries[0].addr;
size = xen_e820_table.entries[0].size;
while (i < xen_e820_table.nr_entries) {
- bool discard = false;
chunk_size = size;
type = xen_e820_table.entries[i].type;
@@ -824,11 +823,10 @@ char * __init xen_memory_setup(void)
xen_add_extra_mem(pfn_s, n_pfns);
xen_max_p2m_pfn = pfn_s + n_pfns;
} else
- discard = true;
+ type = E820_TYPE_UNUSABLE;
}
- if (!discard)
- xen_align_and_add_e820_region(addr, chunk_size, type);
+ xen_align_and_add_e820_region(addr, chunk_size, type);
addr += chunk_size;
size -= chunk_size;
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index f77e499..065f0b6 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -257,10 +257,25 @@ static void release_memory_resource(struct resource
*resource)
kfree(resource);
}
+/*
+ * Host memory not allocated to dom0. We can use this range for hotplug-based
+ * ballooning.
+ *
+ * It's a type-less resource. Setting IORESOURCE_MEM will make resource
+ * management algorithms (arch_remove_reservations()) look into guest e820,
+ * which we don't want.
+ */
+static struct resource hostmem_resource = {
+ .name = "Host RAM",
+};
+
+void __attribute__((weak)) __init arch_xen_balloon_init(struct resource *res)
+{}
+
static struct resource *additional_memory_resource(phys_addr_t size)
{
- struct resource *res;
- int ret;
+ struct resource *res, *res_hostmem;
+ int ret = -ENOMEM;
res = kzalloc(sizeof(*res), GFP_KERNEL);
if (!res)
@@ -269,13 +284,42 @@ static struct resource
*additional_memory_resource(phys_addr_t size)
res->name = "System RAM";
res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
- ret = allocate_resource(&iomem_resource, res,
- size, 0, -1,
- PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
- if (ret < 0) {
- pr_err("Cannot allocate new System RAM resource\n");
- kfree(res);
- return NULL;
+ res_hostmem = kzalloc(sizeof(*res), GFP_KERNEL);
+ if (res_hostmem) {
+ /* Try to grab a range from hostmem */
+ res_hostmem->name = "Host memory";
+ ret = allocate_resource(&hostmem_resource, res_hostmem,
+ size, 0, -1,
+ PAGES_PER_SECTION * PAGE_SIZE, NULL,
NULL);
+ }
+
+ if (!ret) {
+ /*
+ * Insert this resource into iomem. Because hostmem_resource
+ * tracks portion of guest e820 marked as UNUSABLE noone else
+ * should try to use it.
+ */
+ res->start = res_hostmem->start;
+ res->end = res_hostmem->end;
+ ret = insert_resource(&iomem_resource, res);
+ if (ret < 0) {
+ pr_err("Can't insert iomem_resource [%llx - %llx]\n",
+ res->start, res->end);
+ release_memory_resource(res_hostmem);
+ res_hostmem = NULL;
+ res->start = res->end = 0;
+ }
+ }
+
+ if (ret) {
+ ret = allocate_resource(&iomem_resource, res,
+ size, 0, -1,
+ PAGES_PER_SECTION * PAGE_SIZE, NULL,
NULL);
+ if (ret < 0) {
+ pr_err("Cannot allocate new System RAM resource\n");
+ kfree(res);
+ return NULL;
+ }
}
#ifdef CONFIG_SPARSEMEM
@@ -287,6 +331,7 @@ static struct resource
*additional_memory_resource(phys_addr_t size)
pr_err("New System RAM resource outside addressable RAM (%lu
> %lu)\n",
pfn, limit);
release_memory_resource(res);
+ release_memory_resource(res_hostmem);
return NULL;
}
}
@@ -765,6 +810,8 @@ static int __init balloon_init(void)
set_online_page_callback(&xen_online_page);
register_memory_notifier(&xen_memory_nb);
register_sysctl_table(xen_root);
+
+ arch_xen_balloon_init(&hostmem_resource);
#endif
#ifdef CONFIG_XEN_PV
diff --git a/include/xen/balloon.h b/include/xen/balloon.h
index 4914b93..61f410f 100644
--- a/include/xen/balloon.h
+++ b/include/xen/balloon.h
@@ -44,3 +44,8 @@ static inline void xen_balloon_init(void)
{
}
#endif
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+struct resource;
+void arch_xen_balloon_init(struct resource *hostmem_resource);
+#endif
