From be82abe6a76ba8e76f25312566182b0f13c4fbf9 Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Mon, 11 Jul 2022 09:36:32 +0530 Subject: RISC-V: KVM: Fix SRCU deadlock caused by kvm_riscv_check_vcpu_requests() The kvm_riscv_check_vcpu_requests() is called with SRCU read lock held and for KVM_REQ_SLEEP request it will block the VCPU without releasing SRCU read lock. This causes KVM ioctls (such as KVM_IOEVENTFD) from other VCPUs of the same Guest/VM to hang/deadlock if there is any synchronize_srcu() or synchronize_srcu_expedited() in the path. To fix the above in kvm_riscv_check_vcpu_requests(), we should do SRCU read unlock before blocking the VCPU and do SRCU read lock after VCPU wakeup. Fixes: cce69aff689e ("RISC-V: KVM: Implement VCPU interrupts and requests handling") Reported-by: Bin Meng Signed-off-by: Anup Patel Reviewed-by: Atish Patra Tested-by: Heinrich Schuchardt Tested-by: Bin Meng Signed-off-by: Anup Patel --- arch/riscv/kvm/vcpu.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/riscv/kvm') diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index 7f4ad5e4373a..f3455dc013fa 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -781,9 +781,11 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu) if (kvm_request_pending(vcpu)) { if (kvm_check_request(KVM_REQ_SLEEP, vcpu)) { + kvm_vcpu_srcu_read_unlock(vcpu); rcuwait_wait_event(wait, (!vcpu->arch.power_off) && (!vcpu->arch.pause), TASK_INTERRUPTIBLE); + kvm_vcpu_srcu_read_lock(vcpu); if (vcpu->arch.power_off || vcpu->arch.pause) { /* -- cgit v1.2.3