This patch adds support for guest-side frontswap. This is the part which communicates
with the host regarding frontswap TMEM actions.
Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
---
arch/x86/kvm/tmem/Kconfig | 9 +++
arch/x86/kvm/tmem/Makefile | 1 +
arch/x86/kvm/tmem/frontswap.c | 139 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 149 insertions(+), 0 deletions(-)
create mode 100644 arch/x86/kvm/tmem/frontswap.c
diff --git a/arch/x86/kvm/tmem/Kconfig b/arch/x86/kvm/tmem/Kconfig
index 4734db2..ae46299 100644
--- a/arch/x86/kvm/tmem/Kconfig
+++ b/arch/x86/kvm/tmem/Kconfig
@@ -31,4 +31,13 @@ config KVM_TMEM_GUEST_CLEANCACHE
as the TMEM target, which means that cleanswap may be used across
VMs (and even hosts).
+config KVM_TMEM_GUEST_FRONTSWAP
+ bool "Guest-side frontswap support
+ depends on FRONTSWAP
+ select KVM_TMEM_GUEST
+ ---help---
+ This option enables guest to use frontswap with the KVM host acting
+ as the TMEM target, which means that frontswap may be used across
+ VMs (and even hosts).
+
endif # KVM_TMEM
diff --git a/arch/x86/kvm/tmem/Makefile b/arch/x86/kvm/tmem/Makefile
index b972c2b..40c0561 100644
--- a/arch/x86/kvm/tmem/Makefile
+++ b/arch/x86/kvm/tmem/Makefile
@@ -3,3 +3,4 @@ ccflags-y += -Idrivers/staging/zcache/
obj-$(CONFIG_KVM_TMEM_HOST) += host.o
obj-$(CONFIG_KVM_TMEM_GUEST) += guest.o
obj-$(CONFIG_KVM_TMEM_GUEST_CLEANCACHE) += cleancache.o
+obj-$(CONFIG_KVM_TMEM_GUEST_FRONTSWAP) += frontswap.o
diff --git a/arch/x86/kvm/tmem/frontswap.c b/arch/x86/kvm/tmem/frontswap.c
new file mode 100644
index 0000000..b63ac83
--- /dev/null
+++ b/arch/x86/kvm/tmem/frontswap.c
@@ -0,0 +1,139 @@
+/*
+ * KVM TMEM frontswap guest side interface
+ *
+ * Copyright (c) 2012 Sasha Levin
+ *
+ * Based on the equivalent Xen code.
+ *
+ */
+
+#include <linux/kvm_types.h>
+#include <linux/mm.h>
+#include <linux/frontswap.h>
+#include <linux/kvm_para.h>
+
+#include "tmem.h"
+#include "guest.h"
+
+#include <zcache.h>
+
+/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
+static int tmem_frontswap_poolid;
+
+/*
+ * Swizzling increases objects per swaptype, increasing tmem concurrency
+ * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
+ */
+#define SWIZ_BITS 4
+#define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
+#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
+#define iswiz(_ind) (_ind >> SWIZ_BITS)
+
+static inline struct tmem_oid oswiz(unsigned type, __u32 ind)
+{
+ struct tmem_oid oid = { .oid = { 0 } };
+
+ oid.oid[0] = _oswiz(type, ind);
+
+ return oid;
+}
+
+/* returns 0 if the page was successfully put into frontswap, -1 if not */
+static int tmem_frontswap_store(unsigned type, pgoff_t offset,
+ struct page *page)
+{
+ __u32 ind = (__u32)offset;
+ unsigned long pfn = page_to_pfn(page);
+ int pool = tmem_frontswap_poolid;
+
+ if (pool < 0)
+ return -1;
+
+ return kvm_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);
+}
+
+/*
+ * returns 0 if the page was successfully gotten from frontswap, -1 if
+ * was not present (should never happen!)
+ */
+static int tmem_frontswap_load(unsigned type, pgoff_t offset,
+ struct page *page)
+{
+ __u32 ind = (__u32)offset;
+ unsigned long pfn = page_to_pfn(page);
+ int pool = tmem_frontswap_poolid;
+
+ if (pool < 0)
+ return -1;
+
+ return kvm_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);
+}
+
+/* flush a single page from frontswap */
+static void tmem_frontswap_invalidate_page(unsigned type, pgoff_t offset)
+{
+ __u64 ind64 = (__u64)offset;
+ __u32 ind = (__u32)offset;
+ int pool = tmem_frontswap_poolid;
+
+ if (pool < 0)
+ return;
+
+ kvm_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind64));
+}
+
+/* flush all pages from the passed swaptype */
+static void tmem_frontswap_invalidate_area(unsigned type)
+{
+ int pool = tmem_frontswap_poolid;
+ int ind;
+
+ if (pool < 0)
+ return;
+ for (ind = SWIZ_MASK; ind >= 0; ind--)
+ kvm_tmem_flush_object(pool, oswiz(type, ind));
+ kvm_tmem_destroy_pool((u32)pool);
+}
+
+static void tmem_frontswap_init(unsigned ignored)
+{
+ /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
+ if (tmem_frontswap_poolid < 0)
+ tmem_frontswap_poolid =
+ kvm_tmem_new_pool(KVM_CLIENT, TMEM_POOL_PERSIST, PAGE_SIZE);
+}
+
+static int use_kvmfrontswap = 1;
+
+static int __init no_kvmfrontswap(char *s)
+{
+ use_kvmfrontswap = 0;
+ return 1;
+}
+
+__setup("nokvmfrontswap", no_kvmfrontswap);
+
+static struct frontswap_ops tmem_frontswap_ops = {
+ .store = tmem_frontswap_store,
+ .load = tmem_frontswap_load,
+ .invalidate_page = tmem_frontswap_invalidate_page,
+ .invalidate_area = tmem_frontswap_invalidate_area,
+ .init = tmem_frontswap_init
+};
+
+static int kvm_tmem_frontswap_init(void)
+{
+ struct frontswap_ops old_ops;
+
+ if (!use_kvmfrontswap || !kvm_para_available())
+ return 0;
+
+ old_ops = frontswap_register_ops(&tmem_frontswap_ops);
+
+ tmem_frontswap_poolid = -1;
+ printk(KERN_INFO "frontswap enabled, RAM provided by KVM TMEM %s\n",
+ old_ops.init?"(WARNING: frontswap_ops overridden)":"");
+ return 0;
+}
+
+module_init(kvm_tmem_frontswap_init);
--
1.7.8.6
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
