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Subject[PATCH 4/10] KVM: fix rcu usage in init_rmode_* functions
fix:
[ 3494.671786] stack backtrace:
[ 3494.671789] Pid: 10527, comm: qemu-system-x86 Not tainted 2.6.38-rc6+ #23
[ 3494.671790] Call Trace:
[ 3494.671796] [<ffffffff8107d15f>] ? lockdep_rcu_dereference+0x9d/0xa5
[ 3494.671826] [<ffffffffa03498be>] ? kvm_memslots+0x6b/0x73 [kvm]
[ 3494.671834] [<ffffffffa03499be>] ? gfn_to_memslot+0x16/0x4f [kvm]
[ 3494.671843] [<ffffffffa0349a0d>] ? gfn_to_hva+0x16/0x27 [kvm]
[ 3494.671851] [<ffffffffa034c1c4>] ? kvm_write_guest_page+0x31/0x83 [kvm]
[ 3494.671861] [<ffffffffa034c230>] ? kvm_clear_guest_page+0x1a/0x1c [kvm]
[ 3494.671867] [<ffffffffa015e321>] ? vmx_set_tss_addr+0x83/0x122 [kvm_intel]

and:
[ 8328.789599] stack backtrace:
[ 8328.789601] Pid: 18736, comm: qemu-system-x86 Not tainted 2.6.38-rc6+ #23
[ 8328.789603] Call Trace:
[ 8328.789609] [<ffffffff8107d15f>] ? lockdep_rcu_dereference+0x9d/0xa5
[ 8328.789621] [<ffffffffa03988be>] ? kvm_memslots+0x6b/0x73 [kvm]
[ 8328.789628] [<ffffffffa03989be>] ? gfn_to_memslot+0x16/0x4f [kvm]
[ 8328.789635] [<ffffffffa0398a0d>] ? gfn_to_hva+0x16/0x27 [kvm]
[ 8328.789643] [<ffffffffa039b1c4>] ? kvm_write_guest_page+0x31/0x83 [kvm]
[ 8328.789699] [<ffffffffa039b230>] ? kvm_clear_guest_page+0x1a/0x1c [kvm]
[ 8328.789713] [<ffffffffa0206d0e>] ? vmx_create_vcpu+0x316/0x3c8 [kvm_intel]

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/vmx.c | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e2b8c6b..d871ced 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2399,9 +2399,10 @@ static int init_rmode_tss(struct kvm *kvm)
{
gfn_t fn = rmode_tss_base(kvm) >> PAGE_SHIFT;
u16 data = 0;
- int ret = 0;
- int r;
+ int r, idx, ret = 0;

+ idx = srcu_read_lock(&kvm->srcu);
+ fn = rmode_tss_base(kvm) >> PAGE_SHIFT;
r = kvm_clear_guest_page(kvm, fn, 0, PAGE_SIZE);
if (r < 0)
goto out;
@@ -2425,12 +2426,13 @@ static int init_rmode_tss(struct kvm *kvm)

ret = 1;
out:
+ srcu_read_unlock(&kvm->srcu, idx);
return ret;
}

static int init_rmode_identity_map(struct kvm *kvm)
{
- int i, r, ret;
+ int i, idx, r, ret;
pfn_t identity_map_pfn;
u32 tmp;

@@ -2445,6 +2447,7 @@ static int init_rmode_identity_map(struct kvm *kvm)
return 1;
ret = 0;
identity_map_pfn = kvm->arch.ept_identity_map_addr >> PAGE_SHIFT;
+ idx = srcu_read_lock(&kvm->srcu);
r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE);
if (r < 0)
goto out;
@@ -2460,6 +2463,7 @@ static int init_rmode_identity_map(struct kvm *kvm)
kvm->arch.ept_identity_pagetable_done = true;
ret = 1;
out:
+ srcu_read_unlock(&kvm->srcu, idx);
return ret;
}

--
1.7.4


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