From: Anup Patel apatel@ventanamicro.com
[ Upstream commit be82abe6a76ba8e76f25312566182b0f13c4fbf9 ]
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 bmeng.cn@gmail.com Signed-off-by: Anup Patel apatel@ventanamicro.com Reviewed-by: Atish Patra atishp@rivosinc.com Tested-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com Tested-by: Bin Meng bmeng.cn@gmail.com Signed-off-by: Anup Patel anup@brainfault.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/riscv/kvm/vcpu.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index 7461f964d20a..3894777bfa87 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -673,9 +673,11 @@ 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) { /*