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authorSean Christopherson <seanjc@google.com>2022-04-15 00:43:43 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2022-04-21 13:16:11 -0400
commit2031f2876896d82aca7e82f84accd9181b9587fb (patch)
tree3738b7477aeb1e7436fa3a01a0a3ff63d0266952 /arch/s390/kvm
parentfdd6f6ac2e489b9b256cd05a880d13bfdbac7c2e (diff)
KVM: Add helpers to wrap vcpu->srcu_idx and yell if it's abused
Add wrappers to acquire/release KVM's SRCU lock when stashing the index in vcpu->src_idx, along with rudimentary detection of illegal usage, e.g. re-acquiring SRCU and thus overwriting vcpu->src_idx. Because the SRCU index is (currently) either 0 or 1, illegal nesting bugs can go unnoticed for quite some time and only cause problems when the nested lock happens to get a different index. Wrap the WARNs in PROVE_RCU=y, and make them ONCE, otherwise KVM will likely yell so loudly that it will bring the kernel to its knees. Signed-off-by: Sean Christopherson <seanjc@google.com> Tested-by: Fabiano Rosas <farosas@linux.ibm.com> Message-Id: <20220415004343.2203171-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/s390/kvm')
-rw-r--r--arch/s390/kvm/interrupt.c4
-rw-r--r--arch/s390/kvm/kvm-s390.c8
-rw-r--r--arch/s390/kvm/vsie.c4
3 files changed, 8 insertions, 8 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 9b30beac904d..af96dc0549a4 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -1334,11 +1334,11 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
hrtimer_start(&vcpu->arch.ckc_timer, sltime, HRTIMER_MODE_REL);
VCPU_EVENT(vcpu, 4, "enabled wait: %llu ns", sltime);
no_timer:
- srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+ kvm_vcpu_srcu_read_unlock(vcpu);
kvm_vcpu_halt(vcpu);
vcpu->valid_wakeup = false;
__unset_cpu_idle(vcpu);
- vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_vcpu_srcu_read_lock(vcpu);
hrtimer_cancel(&vcpu->arch.ckc_timer);
return 0;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 156d1c25a3c1..da3dabda1a12 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4237,14 +4237,14 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
* We try to hold kvm->srcu during most of vcpu_run (except when run-
* ning the guest), so that memslots (and other stuff) are protected
*/
- vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_vcpu_srcu_read_lock(vcpu);
do {
rc = vcpu_pre_run(vcpu);
if (rc)
break;
- srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+ kvm_vcpu_srcu_read_unlock(vcpu);
/*
* As PF_VCPU will be used in fault handler, between
* guest_enter and guest_exit should be no uaccess.
@@ -4281,12 +4281,12 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
__enable_cpu_timer_accounting(vcpu);
guest_exit_irqoff();
local_irq_enable();
- vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_vcpu_srcu_read_lock(vcpu);
rc = vcpu_post_run(vcpu, exit_reason);
} while (!signal_pending(current) && !guestdbg_exit_pending(vcpu) && !rc);
- srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+ kvm_vcpu_srcu_read_unlock(vcpu);
return rc;
}
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index acda4b6fc851..dada78b92691 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -1091,7 +1091,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
handle_last_fault(vcpu, vsie_page);
- srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+ kvm_vcpu_srcu_read_unlock(vcpu);
/* save current guest state of bp isolation override */
guest_bp_isolation = test_thread_flag(TIF_ISOLATE_BP_GUEST);
@@ -1133,7 +1133,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
if (!guest_bp_isolation)
clear_thread_flag(TIF_ISOLATE_BP_GUEST);
- vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_vcpu_srcu_read_lock(vcpu);
if (rc == -EINTR) {
VCPU_EVENT(vcpu, 3, "%s", "machine check");