From: Anup Patel <Anup.Patel@wdc.com>
To: Palmer Dabbelt <palmer@sifive.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Paolo Bonzini <pbonzini@redhat.com>, Radim K <rkrcmar@redhat.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alexander Graf <graf@amazon.com>,
Atish Patra <Atish.Patra@wdc.com>,
Alistair Francis <Alistair.Francis@wdc.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
Christoph Hellwig <hch@infradead.org>,
Anup Patel <anup@brainfault.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Anup Patel <Anup.Patel@wdc.com>
Subject: [PATCH v9 20/22] RISC-V: KVM: Fix race-condition in kvm_riscv_vcpu_sync_interrupts()
Date: Wed, 16 Oct 2019 16:12:12 +0000 [thread overview]
Message-ID: <20191016160649.24622-21-anup.patel@wdc.com> (raw)
In-Reply-To: <20191016160649.24622-1-anup.patel@wdc.com>
Currently, we sync-up Guest VSIP and VSIE CSRs with HW state upon
VM-exit. This helps us track enable/disable state of interrupts
and VSIP.SSIP bit updates by Guest.
Unfortunately, the implementation of kvm_riscv_vcpu_sync_interrupts()
is racey when running SMP Guest on SMP Host because it can happen
that IRQ_S_SOFT is already queued from other Host CPU and we might
accidentally clear a valid pending IRQ_S_SOFT.
To fix this, we use test_and_set_bit() to update irqs_pending_mask
in kvm_riscv_vcpu_sync_interrupts() instead of directly calling
kvm_riscv_vcpu_set/unset_interrupt() functions.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
arch/riscv/kvm/vcpu.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index f1a218d3a8cf..844542dd13e4 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -662,15 +662,22 @@ void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu)
void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
{
- vcpu->arch.guest_csr.vsip = csr_read(CSR_VSIP);
- vcpu->arch.guest_csr.vsie = csr_read(CSR_VSIE);
+ unsigned long vsip;
+ struct kvm_vcpu_arch *v = &vcpu->arch;
+ struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
- /* Guest can directly update VSIP software interrupt bits */
- if (vcpu->arch.guest_csr.vsip ^ READ_ONCE(vcpu->arch.irqs_pending)) {
- if (vcpu->arch.guest_csr.vsip & (1UL << IRQ_S_SOFT))
- kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_S_SOFT);
- else
- kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_S_SOFT);
+ /* Read current VSIP and VSIE CSRs */
+ vsip = csr_read(CSR_VSIP);
+ csr->vsie = csr_read(CSR_VSIE);
+
+ /* Sync-up VSIP.SSIP bit changes does by Guest */
+ if ((csr->vsip ^ vsip) & (1UL << IRQ_S_SOFT)) {
+ if (!test_and_set_bit(IRQ_S_SOFT, &v->irqs_pending_mask)) {
+ if (vsip & (1UL << IRQ_S_SOFT))
+ set_bit(IRQ_S_SOFT, &v->irqs_pending);
+ else
+ clear_bit(IRQ_S_SOFT, &v->irqs_pending);
+ }
}
}
--
2.17.1
next prev parent reply other threads:[~2019-10-16 16:12 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 16:08 [PATCH v9 00/22] KVM RISC-V Support Anup Patel
2019-10-16 16:08 ` [PATCH v9 01/22] RISC-V: Add bitmap reprensenting ISA features common across CPUs Anup Patel
2019-10-17 8:48 ` Anup Patel
2019-10-25 23:30 ` Paul Walmsley
2019-10-16 16:08 ` [PATCH v9 02/22] RISC-V: Add hypervisor extension related CSR defines Anup Patel
2019-10-16 16:08 ` [PATCH v9 03/22] RISC-V: Add initial skeletal KVM support Anup Patel
2019-11-20 8:04 ` Paul Walmsley
2019-10-16 16:08 ` [PATCH v9 04/22] RISC-V: KVM: Implement VCPU create, init and destroy functions Anup Patel
2019-10-16 16:09 ` [PATCH v9 05/22] RISC-V: KVM: Implement VCPU interrupts and requests handling Anup Patel
2019-10-16 16:09 ` [PATCH v9 06/22] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls Anup Patel
2019-10-16 16:09 ` [PATCH v9 07/22] RISC-V: KVM: Implement VCPU world-switch Anup Patel
2019-10-16 16:09 ` [PATCH v9 08/22] RISC-V: KVM: Handle MMIO exits for VCPU Anup Patel
2019-10-16 16:10 ` [PATCH v9 09/22] RISC-V: KVM: Handle WFI " Anup Patel
2019-10-16 16:10 ` [PATCH v9 10/22] RISC-V: KVM: Implement VMID allocator Anup Patel
2019-10-16 16:10 ` [PATCH v9 11/22] RISC-V: KVM: Implement stage2 page table programming Anup Patel
2019-10-16 16:10 ` [PATCH v9 12/22] RISC-V: KVM: Implement MMU notifiers Anup Patel
2019-10-16 16:10 ` [PATCH v9 13/22] RISC-V: KVM: Add timer functionality Anup Patel
2019-12-04 16:08 ` Daniel Lezcano
2019-10-16 16:10 ` [PATCH v9 14/22] RISC-V: KVM: FP lazy save/restore Anup Patel
2019-10-16 16:11 ` [PATCH v9 15/22] RISC-V: KVM: Implement ONE REG interface for FP registers Anup Patel
2019-10-16 16:11 ` [PATCH v9 16/22] RISC-V: KVM: Add SBI v0.1 support Anup Patel
2019-10-16 16:11 ` [PATCH v9 17/22] RISC-V: KVM: Forward unhandled SBI calls to userspace Anup Patel
2019-10-16 16:11 ` [PATCH v9 18/22] RISC-V: KVM: Simplify stage2 page table programming Anup Patel
2019-10-21 17:31 ` Paolo Bonzini
2019-10-22 5:12 ` Anup Patel
2019-10-16 16:12 ` [PATCH v9 19/22] RISC-V: KVM: Remove per-CPU vsip_shadow variable Anup Patel
2019-10-21 17:28 ` Paolo Bonzini
2019-10-22 5:09 ` Anup Patel
2019-10-16 16:12 ` Anup Patel [this message]
2019-10-21 17:27 ` [PATCH v9 20/22] RISC-V: KVM: Fix race-condition in kvm_riscv_vcpu_sync_interrupts() Paolo Bonzini
2019-10-22 5:07 ` Anup Patel
2019-10-16 16:12 ` [PATCH v9 21/22] RISC-V: KVM: Document RISC-V specific parts of KVM API Anup Patel
2019-10-16 16:12 ` [PATCH v9 22/22] RISC-V: KVM: Add MAINTAINERS entry Anup Patel
2019-10-25 23:10 ` [PATCH v9 00/22] KVM RISC-V Support Paul Walmsley
2019-10-26 3:22 ` Anup Patel
2019-10-26 5:33 ` Christoph Hellwig
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