From: Akshay Karle <[email protected]>
Subject: [RFC 1/2] kvm: host-side changes for tmem on KVM
Working at host:
Once the guest exits to the kvm host, the host determines that the guest exited
to perform some tmem operation(done at kvm_emulate_hypercall)and then
we use zcache to implement this required operations(performed by
kvm_pv_tmem_op).
---
Diffstat for host patch:
arch/x86/include/asm/kvm_host.h | 1
arch/x86/kvm/x86.c | 4 +
drivers/staging/zcache/zcache-main.c | 98 ++++++++++++++++++++++++++++++++---
3 files changed, 95 insertions(+), 8 deletions(-)
diff -Napur vanilla/linux-3.1.5/arch/x86/include/asm/kvm_host.h
linux-3.1.5//arch/x86/include/asm/kvm_host.h
--- vanilla/linux-3.1.5/arch/x86/include/asm/kvm_host.h 2011-12-09
22:27:05.000000000 +0530
+++ linux-3.1.5//arch/x86/include/asm/kvm_host.h 2012-03-05
14:09:41.648006153 +0530
@@ -668,6 +668,7 @@ int emulator_write_phys(struct kvm_vcpu
const void *val, int bytes);
int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
gpa_t addr, unsigned long *ret);
+int kvm_pv_tmem_op(struct kvm_vcpu *vcpu, gpa_t addr, unsigned long *ret);
u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
extern bool tdp_enabled;
diff -Napur vanilla/linux-3.1.5/arch/x86/kvm/x86.c
linux-3.1.5//arch/x86/kvm/x86.c
--- vanilla/linux-3.1.5/arch/x86/kvm/x86.c 2011-12-09 22:27:05.000000000
+0530
+++ linux-3.1.5//arch/x86/kvm/x86.c 2012-03-05 14:09:41.652006083 +0530
@@ -5267,6 +5267,10 @@ int kvm_emulate_hypercall(struct kvm_vcp
case KVM_HC_MMU_OP:
r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
break;
+ case KVM_HC_TMEM:
+ r = kvm_pv_tmem_op(vcpu, a0, &ret);
+ ret = ret - 1000;
+ break;
default:
ret = -KVM_ENOSYS;
break;
diff -Napur vanilla/linux-3.1.5/drivers/staging/zcache/zcache-main.c
linux-3.1.5//drivers/staging/zcache/zcache-main.c
--- vanilla/linux-3.1.5/drivers/staging/zcache/zcache-main.c 2011-12-09
22:27:05.000000000 +0530
+++ linux-3.1.5//drivers/staging/zcache/zcache-main.c 2012-03-05
14:10:31.264006031 +0530
@@ -30,6 +30,7 @@
#include <linux/atomic.h>
#include <linux/math64.h>
#include "tmem.h"
+#include "kvm-tmem.h"
#include "../zram/xvmalloc.h" /* if built in drivers/staging */
@@ -669,7 +670,6 @@ static struct zv_hdr *zv_create(struct x
int chunks = (alloc_size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
int ret;
- BUG_ON(!irqs_disabled());
BUG_ON(chunks >= NCHUNKS);
ret = xv_malloc(xvpool, alloc_size,
&page, &offset, ZCACHE_GFP_MASK);
@@ -1313,7 +1313,6 @@ static int zcache_compress(struct page *
unsigned char *wmem = __get_cpu_var(zcache_workmem);
char *from_va;
- BUG_ON(!irqs_disabled());
if (unlikely(dmem == NULL || wmem == NULL))
goto out; /* no buffer, so can't compress */
from_va = kmap_atomic(from, KM_USER0);
@@ -1533,7 +1532,6 @@ static int zcache_put_page(int cli_id, i
struct tmem_pool *pool;
int ret = -1;
- BUG_ON(!irqs_disabled());
pool = zcache_get_pool_by_id(cli_id, pool_id);
if (unlikely(pool == NULL))
goto out;
@@ -1898,6 +1896,67 @@ struct frontswap_ops zcache_frontswap_re
#endif
/*
+ * tmem op to support tmem in kvm guests
+ */
+
+int kvm_pv_tmem_op(struct kvm_vcpu *vcpu, gpa_t addr, unsigned long *ret)
+{
+ struct tmem_ops op;
+ struct tmem_oid oid;
+ uint64_t pfn;
+ struct page *page;
+ int r;
+
+ r = kvm_read_guest(vcpu->kvm, addr, &op, sizeof(op));
+ if (r < 0)
+ return r;
+
+ switch (op.cmd) {
+ case TMEM_NEW_POOL:
+ *ret = zcache_new_pool(op.u.new.cli_id, op.u.new.flags);
+ break;
+ case TMEM_DESTROY_POOL:
+ *ret = zcache_destroy_pool(op.u.gen.cli_id, op.pool_id);
+ break;
+ case TMEM_NEW_PAGE:
+ break;
+ case TMEM_PUT_PAGE:
+ pfn = gfn_to_pfn(vcpu->kvm, op.u.gen.pfn);
+ page = pfn_to_page(pfn);
+ oid.oid[0] = op.u.gen.oid[0];
+ oid.oid[1] = op.u.gen.oid[1];
+ oid.oid[2] = op.u.gen.oid[2];
+ VM_BUG_ON(!PageLocked(page));
+ *ret = zcache_put_page(op.u.gen.cli_id, op.pool_id,
+ &oid, op.u.gen.index, page);
+ break;
+ case TMEM_GET_PAGE:
+ pfn = gfn_to_pfn(vcpu->kvm, op.u.gen.pfn);
+ page = pfn_to_page(pfn);
+ oid.oid[0] = op.u.gen.oid[0];
+ oid.oid[1] = op.u.gen.oid[1];
+ oid.oid[2] = op.u.gen.oid[2];
+ *ret = zcache_get_page(TMEM_CLI, op.pool_id,
+ &oid, op.u.gen.index, page);
+ break;
+ case TMEM_FLUSH_PAGE:
+ oid.oid[0] = op.u.gen.oid[0];
+ oid.oid[1] = op.u.gen.oid[1];
+ oid.oid[2] = op.u.gen.oid[2];
+ *ret = zcache_flush_page(op.u.gen.cli_id, op.pool_id,
+ &oid, op.u.gen.index);
+ break;
+ case TMEM_FLUSH_OBJECT:
+ oid.oid[0] = op.u.gen.oid[0];
+ oid.oid[1] = op.u.gen.oid[1];
+ oid.oid[2] = op.u.gen.oid[2];
+ *ret = zcache_flush_object(op.u.gen.cli_id, op.pool_id, &oid);
+ break;
+ }
+ return 0;
+}
+
+/*
* zcache initialization
* NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR
* NOTHING HAPPENS!
@@ -1934,10 +1993,19 @@ static int __init no_frontswap(char *s)
__setup("nofrontswap", no_frontswap);
+static int kvm_tmem_enabled = 0;
+
+static int __init enable_kvm_tmem(char *s)
+{
+ kvm_tmem_enabled = 1;
+ return 1;
+}
+
+__setup("kvmtmem", enable_kvm_tmem);
+
static int __init zcache_init(void)
{
int ret = 0;
-
#ifdef CONFIG_SYSFS
ret = sysfs_create_group(mm_kobj, &zcache_attr_group);
if (ret) {
@@ -1946,7 +2014,7 @@ static int __init zcache_init(void)
}
#endif /* CONFIG_SYSFS */
#if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP)
- if (zcache_enabled) {
+ if (zcache_enabled || kvm_tmem_enabled) {
unsigned int cpu;
tmem_register_hostops(&zcache_hostops);
@@ -1966,11 +2034,25 @@ static int __init zcache_init(void)
sizeof(struct tmem_objnode), 0, 0, NULL);
zcache_obj_cache = kmem_cache_create("zcache_obj",
sizeof(struct tmem_obj), 0, 0, NULL);
- ret = zcache_new_client(LOCAL_CLIENT);
- if (ret) {
- pr_err("zcache: can't create client\n");
+ if(kvm_tmem_enabled) {
+ ret = zcache_new_client(TMEM_CLI);
+ if(ret) {
+ pr_err("zcache: can't create client\n");
+ goto out;
+ }
+ zbud_init();
+ register_shrinker(&zcache_shrinker);
+ pr_info("zcache: transcendent memory enabled using kernel "
+ "for kvm guests\n");
goto out;
}
+ else {
+ ret = zcache_new_client(LOCAL_CLIENT);
+ if (ret) {
+ pr_err("zcache: can't create client\n");
+ goto out;
+ }
+ }
#endif
#ifdef CONFIG_CLEANCACHE
if (zcache_enabled && use_cleancache) {
--
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