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| author | Anup Patel <apatel@ventanamicro.com> | 2022-07-11 09:36:32 +0530 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2022-07-11 09:36:32 +0530 |
| commit | be82abe6a76ba8e76f25312566182b0f13c4fbf9 (patch) | |
| tree | 66d4c7e41c5055d0fa865316547b3085dce1ec64 /arch/riscv | |
| parent | 88573389aaa34640b9ecde15622c68e8737d8f8c (diff) | |
| download | linux-be82abe6a76ba8e76f25312566182b0f13c4fbf9.tar.gz linux-be82abe6a76ba8e76f25312566182b0f13c4fbf9.tar.bz2 linux-be82abe6a76ba8e76f25312566182b0f13c4fbf9.zip | |
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 <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>
Diffstat (limited to 'arch/riscv')
| -rw-r--r-- | arch/riscv/kvm/vcpu.c | 2 |
1 files changed, 2 insertions, 0 deletions
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) { /* |