From 4a937f96f3a29c58b7edd349d2e4dfac371efdf2 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 10 Sep 2013 12:58:35 +0200 Subject: [PATCH] KVM: protect kvm_usage_count with its own spinlock The VM list need not be protected by a raw spinlock. Separate the two so that kvm_lock can be made non-raw. Cc: kvm@vger.kernel.org Cc: gleb@redhat.com Cc: jan.kiszka@siemens.com Reviewed-by: Gleb Natapov Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/locking.txt | 6 +++++- virt/kvm/kvm_main.c | 19 ++++++++++--------- 2 files changed, 15 insertions(+), 10 deletions(-) diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt index a9f366e73c8e..ba9e1c2150c2 100644 --- a/Documentation/virtual/kvm/locking.txt +++ b/Documentation/virtual/kvm/locking.txt @@ -135,7 +135,11 @@ Name: kvm_lock Type: raw_spinlock Arch: any Protects: - vm_list - - hardware virtualization enable/disable + +Name: kvm_count_lock +Type: raw_spinlock_t +Arch: any +Protects: - hardware virtualization enable/disable Comment: 'raw' because hardware enabling/disabling must be atomic /wrt migration. diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 426051d66173..eb94343c2ed2 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -71,6 +71,7 @@ MODULE_LICENSE("GPL"); */ DEFINE_RAW_SPINLOCK(kvm_lock); +static DEFINE_RAW_SPINLOCK(kvm_count_lock); LIST_HEAD(vm_list); static cpumask_var_t cpus_hardware_enabled; @@ -2683,10 +2684,10 @@ static void hardware_enable_nolock(void *junk) static void hardware_enable(void) { - raw_spin_lock(&kvm_lock); + raw_spin_lock(&kvm_count_lock); if (kvm_usage_count) hardware_enable_nolock(NULL); - raw_spin_unlock(&kvm_lock); + raw_spin_unlock(&kvm_count_lock); } static void hardware_disable_nolock(void *junk) @@ -2701,10 +2702,10 @@ static void hardware_disable_nolock(void *junk) static void hardware_disable(void) { - raw_spin_lock(&kvm_lock); + raw_spin_lock(&kvm_count_lock); if (kvm_usage_count) hardware_disable_nolock(NULL); - raw_spin_unlock(&kvm_lock); + raw_spin_unlock(&kvm_count_lock); } static void hardware_disable_all_nolock(void) @@ -2718,16 +2719,16 @@ static void hardware_disable_all_nolock(void) static void hardware_disable_all(void) { - raw_spin_lock(&kvm_lock); + raw_spin_lock(&kvm_count_lock); hardware_disable_all_nolock(); - raw_spin_unlock(&kvm_lock); + raw_spin_unlock(&kvm_count_lock); } static int hardware_enable_all(void) { int r = 0; - raw_spin_lock(&kvm_lock); + raw_spin_lock(&kvm_count_lock); kvm_usage_count++; if (kvm_usage_count == 1) { @@ -2740,7 +2741,7 @@ static int hardware_enable_all(void) } } - raw_spin_unlock(&kvm_lock); + raw_spin_unlock(&kvm_count_lock); return r; } @@ -3130,7 +3131,7 @@ static int kvm_suspend(void) static void kvm_resume(void) { if (kvm_usage_count) { - WARN_ON(raw_spin_is_locked(&kvm_lock)); + WARN_ON(raw_spin_is_locked(&kvm_count_lock)); hardware_enable_nolock(NULL); } } -- 2.20.1