| Message ID | 20240417074528.16506-1-yongxuan.wang@sifive.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | RISCV: KVM: Avoid lock inversion in SBI_EXT_HSM_HART_START | expand |
On Wed, Apr 17, 2024 at 1:15 PM Yong-Xuan Wang <yongxuan.wang@sifive.com> wrote: > > Documentation/virt/kvm/locking.rst advises that kvm->lock should be > acquired outside vcpu->mutex and kvm->srcu. However, when KVM/RISC-V > handling SBI_EXT_HSM_HART_START, the lock ordering is vcpu->mutex, > kvm->srcu then kvm->lock. > > The use of kvm->lock over there ensures that only one VCPU can update > the reset context and call SBI_EXT_HSM_HART_START for the target VCPU > simultaneously. This patchset divides it into 2 separate spinlock, and > replace vcpu->power_off with vcpu->mp_state. > > --- > v2: > - rename the hsm_start_lock to mp_state_lock > - replace vcpu->power_off with vcpu->mp_state in PATCH1 > - add vcpu->reset_cntx_lock in PATCH2 > > Yong-Xuan Wang (2): > RISCV: KVM: Introduce mp_state_lock to avoid lock inversion in > SBI_EXT_HSM_HART_START > RISCV: KVM: Introduce vcpu->reset_cntx_lock Queued this series for Linux-6.10 Thanks, Anup > > arch/riscv/include/asm/kvm_host.h | 8 +++- > arch/riscv/kvm/vcpu.c | 62 ++++++++++++++++++++++++------- > arch/riscv/kvm/vcpu_sbi.c | 7 +++- > arch/riscv/kvm/vcpu_sbi_hsm.c | 26 +++++++++---- > 4 files changed, 78 insertions(+), 25 deletions(-) > > -- > 2.17.1 > > > -- > kvm-riscv mailing list > kvm-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kvm-riscv
Documentation/virt/kvm/locking.rst advises that kvm->lock should be acquired outside vcpu->mutex and kvm->srcu. However, when KVM/RISC-V handling SBI_EXT_HSM_HART_START, the lock ordering is vcpu->mutex, kvm->srcu then kvm->lock. The use of kvm->lock over there ensures that only one VCPU can update the reset context and call SBI_EXT_HSM_HART_START for the target VCPU simultaneously. This patchset divides it into 2 separate spinlock, and replace vcpu->power_off with vcpu->mp_state. --- v2: - rename the hsm_start_lock to mp_state_lock - replace vcpu->power_off with vcpu->mp_state in PATCH1 - add vcpu->reset_cntx_lock in PATCH2 Yong-Xuan Wang (2): RISCV: KVM: Introduce mp_state_lock to avoid lock inversion in SBI_EXT_HSM_HART_START RISCV: KVM: Introduce vcpu->reset_cntx_lock arch/riscv/include/asm/kvm_host.h | 8 +++- arch/riscv/kvm/vcpu.c | 62 ++++++++++++++++++++++++------- arch/riscv/kvm/vcpu_sbi.c | 7 +++- arch/riscv/kvm/vcpu_sbi_hsm.c | 26 +++++++++---- 4 files changed, 78 insertions(+), 25 deletions(-)