KVM: use the correct RCU API for PROVE_RCU=y

The RCU/SRCU API have already changed for proving RCU usage.

I got the following dmesg when PROVE_RCU=y because we used incorrect API.
This patch coverts rcu_deference() to srcu_dereference() or family API.

===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
arch/x86/kvm/mmu.c:3020 invoked rcu_dereference_check() without protection!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
2 locks held by qemu-system-x86/8550:
 #0:  (&kvm->slots_lock){+.+.+.}, at: [<ffffffffa011a6ac>] kvm_set_memory_region+0x29/0x50 [kvm]
 #1:  (&(&kvm->mmu_lock)->rlock){+.+...}, at: [<ffffffffa012262d>] kvm_arch_commit_memory_region+0xa6/0xe2 [kvm]

stack backtrace:
Pid: 8550, comm: qemu-system-x86 Not tainted 2.6.34-rc4-tip-01028-g939eab1 #27
Call Trace:
 [<ffffffff8106c59e>] lockdep_rcu_dereference+0xaa/0xb3
 [<ffffffffa012f6c1>] kvm_mmu_calculate_mmu_pages+0x44/0x7d [kvm]
 [<ffffffffa012263e>] kvm_arch_commit_memory_region+0xb7/0xe2 [kvm]
 [<ffffffffa011a5d7>] __kvm_set_memory_region+0x636/0x6e2 [kvm]
 [<ffffffffa011a6ba>] kvm_set_memory_region+0x37/0x50 [kvm]
 [<ffffffffa015e956>] vmx_set_tss_addr+0x46/0x5a [kvm_intel]
 [<ffffffffa0126592>] kvm_arch_vm_ioctl+0x17a/0xcf8 [kvm]
 [<ffffffff810a8692>] ? unlock_page+0x27/0x2c
 [<ffffffff810bf879>] ? __do_fault+0x3a9/0x3e1
 [<ffffffffa011b12f>] kvm_vm_ioctl+0x364/0x38d [kvm]
 [<ffffffff81060cfa>] ? up_read+0x23/0x3d
 [<ffffffff810f3587>] vfs_ioctl+0x32/0xa6
 [<ffffffff810f3b19>] do_vfs_ioctl+0x495/0x4db
 [<ffffffff810e6b2f>] ? fget_light+0xc2/0x241
 [<ffffffff810e416c>] ? do_sys_open+0x104/0x116
 [<ffffffff81382d6d>] ? retint_swapgs+0xe/0x13
 [<ffffffff810f3ba6>] sys_ioctl+0x47/0x6a
 [<ffffffff810021db>] system_call_fastpath+0x16/0x1b

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d6351a34b297..4901ec5061ba 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -834,7 +834,7 @@ EXPORT_SYMBOL_GPL(kvm_is_error_hva);
 struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn)
 {
         int i;
-        struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
+        struct kvm_memslots *slots = kvm_memslots(kvm);
 
         for (i = 0; i < slots->nmemslots; ++i) {
                 struct kvm_memory_slot *memslot = &slots->memslots[i];
@@ -856,7 +856,7 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 {
         int i;
-        struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
+        struct kvm_memslots *slots = kvm_memslots(kvm);
 
         gfn = unalias_gfn_instantiation(kvm, gfn);
         for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
@@ -900,7 +900,7 @@ out:
 int memslot_id(struct kvm *kvm, gfn_t gfn)
 {
         int i;
-        struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
+        struct kvm_memslots *slots = kvm_memslots(kvm);
         struct kvm_memory_slot *memslot = NULL;
 
         gfn = unalias_gfn(kvm, gfn);
@@ -1994,7 +1994,9 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
                      int len, const void *val)
 {
         int i;
-        struct kvm_io_bus *bus = rcu_dereference(kvm->buses[bus_idx]);
+        struct kvm_io_bus *bus;
+
+        bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
         for (i = 0; i < bus->dev_count; i++)
                 if (!kvm_iodevice_write(bus->devs[i], addr, len, val))
                         return 0;
@@ -2006,8 +2008,9 @@ int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
                     int len, void *val)
 {
         int i;
-        struct kvm_io_bus *bus = rcu_dereference(kvm->buses[bus_idx]);
+        struct kvm_io_bus *bus;
 
+        bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
         for (i = 0; i < bus->dev_count; i++)
                 if (!kvm_iodevice_read(bus->devs[i], addr, len, val))
                         return 0;