| Message ID | 20260901080610.91993-1-pengpeng@iscas.ac.cn |
|---|---|
| State | New |
| Headers | show |
| Series | RISC-V: KVM: Preserve LCOFIP when checking pending interrupts | expand |
Hi, On 9/1/26 4:06 PM, Pengpeng Hou wrote: > KVM injects the guest counter-overflow interrupt into HVIP bit 13 and > records the same bit in irqs_pending. The guest enables it through VSIE > LCOFIE, also at bit 13. > > kvm_riscv_vcpu_has_interrupts() shifts the complete VSIP valid mask by > VSIP_TO_HVIP_SHIFT before matching it against irqs_pending. That maps > SSIP, STIP, and SEIP to VSSIP, VSTIP, and VSEIP, but incorrectly moves > LCOFIP from bit 13 to bit 14. The following high-interrupt term excludes > all local interrupt bits, so it cannot recover LCOFIP. > > As a result, kvm_arch_vcpu_runnable() can report false for a vCPU waiting > in WFI even though an enabled PMU overflow interrupt is pending. > > Keep LCOFIP in place while shifting the three interrupt classes that have > distinct VS-level bit positions. This makes a vCPU halted in WFI runnable > when its PMU overflow interrupt is pending. > > Fixes: 16b0bde9a37c ("RISC-V: KVM: Add perf sampling support for guests") > Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn> i suppose it's a vsip/hvip conversion bug but currently only lcofi will trigger this. a fix for the conversion: https://lore.kernel.org/linux-riscv/20260804134018.85497-1-yang.yicong@picoheart.com/ > --- > arch/riscv/kvm/vcpu.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index e062ca1..c6eb3bd 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -487,12 +487,14 @@ int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) > bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, u64 mask) > { > unsigned long flags; > - unsigned long ie; > + unsigned long ie, vsie; > bool ret; > > raw_spin_lock_irqsave(&vcpu->arch.irqs_pending_lock, flags); > - ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK) > - << VSIP_TO_HVIP_SHIFT) & (unsigned long)mask; > + vsie = vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK; > + ie = ((vsie & ~SIP_LCOFIP) << VSIP_TO_HVIP_SHIFT) | > + (vsie & SIP_LCOFIP); > + ie &= (unsigned long)mask; > ie |= vcpu->arch.guest_csr.vsie & ~IRQ_LOCAL_MASK & > (unsigned long)mask; > ret = vcpu->arch.irqs_pending[0] & ie; > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c index e062ca1..c6eb3bd 100644 --- a/arch/riscv/kvm/vcpu.c +++ b/arch/riscv/kvm/vcpu.c @@ -487,12 +487,14 @@ int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq) bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, u64 mask) { unsigned long flags; - unsigned long ie; + unsigned long ie, vsie; bool ret; raw_spin_lock_irqsave(&vcpu->arch.irqs_pending_lock, flags); - ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK) - << VSIP_TO_HVIP_SHIFT) & (unsigned long)mask; + vsie = vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK; + ie = ((vsie & ~SIP_LCOFIP) << VSIP_TO_HVIP_SHIFT) | + (vsie & SIP_LCOFIP); + ie &= (unsigned long)mask; ie |= vcpu->arch.guest_csr.vsie & ~IRQ_LOCAL_MASK & (unsigned long)mask; ret = vcpu->arch.irqs_pending[0] & ie;
KVM injects the guest counter-overflow interrupt into HVIP bit 13 and records the same bit in irqs_pending. The guest enables it through VSIE LCOFIE, also at bit 13. kvm_riscv_vcpu_has_interrupts() shifts the complete VSIP valid mask by VSIP_TO_HVIP_SHIFT before matching it against irqs_pending. That maps SSIP, STIP, and SEIP to VSSIP, VSTIP, and VSEIP, but incorrectly moves LCOFIP from bit 13 to bit 14. The following high-interrupt term excludes all local interrupt bits, so it cannot recover LCOFIP. As a result, kvm_arch_vcpu_runnable() can report false for a vCPU waiting in WFI even though an enabled PMU overflow interrupt is pending. Keep LCOFIP in place while shifting the three interrupt classes that have distinct VS-level bit positions. This makes a vCPU halted in WFI runnable when its PMU overflow interrupt is pending. Fixes: 16b0bde9a37c ("RISC-V: KVM: Add perf sampling support for guests") Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn> --- arch/riscv/kvm/vcpu.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)