From: Oliver Upton <oupton@google.com> To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>, Ricardo Koller <ricarkol@google.com>, Jing Zhang <jingzhangos@google.com>, Raghavendra Rao Anata <rananta@google.com>, James Morse <james.morse@arm.com>, Alexandru Elisei <alexandru.elisei@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Oliver Upton <oupton@google.com> Subject: [PATCH 1/4] KVM: arm64: Fix read-side race on updates to vcpu reset state Date: Wed, 18 Aug 2021 08:50:44 +0000 [thread overview] Message-ID: <20210818085047.1005285-2-oupton@google.com> (raw) In-Reply-To: <20210818085047.1005285-1-oupton@google.com> KVM correctly serializes writes to a vCPU's reset state, however since we do not take the KVM lock on the read side it is entirely possible to read state from two different reset requests. Cure the race for now by taking the KVM lock when reading the reset_state structure. Fixes: 358b28f09f0a ("arm/arm64: KVM: Allow a VCPU to fully reset itself") Signed-off-by: Oliver Upton <oupton@google.com> --- arch/arm64/kvm/reset.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 18ffc6ad67b8..3507e64ff8ad 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -210,10 +210,16 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu) */ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) { + struct vcpu_reset_state reset_state; int ret; bool loaded; u32 pstate; + mutex_lock(&vcpu->kvm->lock); + memcpy(&reset_state, &vcpu->arch.reset_state, sizeof(reset_state)); + vcpu->arch.reset_state.reset = false; + mutex_unlock(&vcpu->kvm->lock); + /* Reset PMU outside of the non-preemptible section */ kvm_pmu_vcpu_reset(vcpu); @@ -276,8 +282,8 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) * Additional reset state handling that PSCI may have imposed on us. * Must be done after all the sys_reg reset. */ - if (vcpu->arch.reset_state.reset) { - unsigned long target_pc = vcpu->arch.reset_state.pc; + if (reset_state.reset) { + unsigned long target_pc = reset_state.pc; /* Gracefully handle Thumb2 entry point */ if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) { @@ -286,13 +292,11 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) } /* Propagate caller endianness */ - if (vcpu->arch.reset_state.be) + if (reset_state.be) kvm_vcpu_set_be(vcpu); *vcpu_pc(vcpu) = target_pc; - vcpu_set_reg(vcpu, 0, vcpu->arch.reset_state.r0); - - vcpu->arch.reset_state.reset = false; + vcpu_set_reg(vcpu, 0, reset_state.r0); } /* Reset timer */ -- 2.33.0.rc1.237.g0d66db33f3-goog
WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oupton@google.com> To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>, Raghavendra Rao Anata <rananta@google.com> Subject: [PATCH 1/4] KVM: arm64: Fix read-side race on updates to vcpu reset state Date: Wed, 18 Aug 2021 08:50:44 +0000 [thread overview] Message-ID: <20210818085047.1005285-2-oupton@google.com> (raw) In-Reply-To: <20210818085047.1005285-1-oupton@google.com> KVM correctly serializes writes to a vCPU's reset state, however since we do not take the KVM lock on the read side it is entirely possible to read state from two different reset requests. Cure the race for now by taking the KVM lock when reading the reset_state structure. Fixes: 358b28f09f0a ("arm/arm64: KVM: Allow a VCPU to fully reset itself") Signed-off-by: Oliver Upton <oupton@google.com> --- arch/arm64/kvm/reset.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 18ffc6ad67b8..3507e64ff8ad 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -210,10 +210,16 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu) */ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) { + struct vcpu_reset_state reset_state; int ret; bool loaded; u32 pstate; + mutex_lock(&vcpu->kvm->lock); + memcpy(&reset_state, &vcpu->arch.reset_state, sizeof(reset_state)); + vcpu->arch.reset_state.reset = false; + mutex_unlock(&vcpu->kvm->lock); + /* Reset PMU outside of the non-preemptible section */ kvm_pmu_vcpu_reset(vcpu); @@ -276,8 +282,8 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) * Additional reset state handling that PSCI may have imposed on us. * Must be done after all the sys_reg reset. */ - if (vcpu->arch.reset_state.reset) { - unsigned long target_pc = vcpu->arch.reset_state.pc; + if (reset_state.reset) { + unsigned long target_pc = reset_state.pc; /* Gracefully handle Thumb2 entry point */ if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) { @@ -286,13 +292,11 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) } /* Propagate caller endianness */ - if (vcpu->arch.reset_state.be) + if (reset_state.be) kvm_vcpu_set_be(vcpu); *vcpu_pc(vcpu) = target_pc; - vcpu_set_reg(vcpu, 0, vcpu->arch.reset_state.r0); - - vcpu->arch.reset_state.reset = false; + vcpu_set_reg(vcpu, 0, reset_state.r0); } /* Reset timer */ -- 2.33.0.rc1.237.g0d66db33f3-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2021-08-18 8:51 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-18 8:50 [PATCH 0/4] KVM: arm64: Fix some races in CPU_ON PSCI call Oliver Upton 2021-08-18 8:50 ` Oliver Upton 2021-08-18 8:50 ` Oliver Upton [this message] 2021-08-18 8:50 ` [PATCH 1/4] KVM: arm64: Fix read-side race on updates to vcpu reset state Oliver Upton 2021-08-18 10:06 ` Marc Zyngier 2021-08-18 10:06 ` Marc Zyngier 2021-08-18 8:50 ` [PATCH 2/4] KVM: arm64: Handle PSCI resets before userspace touches vCPU state Oliver Upton 2021-08-18 8:50 ` Oliver Upton 2021-08-18 10:38 ` Marc Zyngier 2021-08-18 10:38 ` Marc Zyngier 2021-08-18 8:50 ` [PATCH 3/4] KVM: arm64: Enforce reserved bits for PSCI target affinities Oliver Upton 2021-08-18 8:50 ` Oliver Upton 2021-08-18 11:12 ` Marc Zyngier 2021-08-18 11:12 ` Marc Zyngier 2021-08-18 8:50 ` [PATCH 4/4] selftests: KVM: Introduce psci_cpu_on_test Oliver Upton 2021-08-18 8:50 ` Oliver Upton 2021-08-18 14:42 ` Andrew Jones 2021-08-18 14:42 ` Andrew Jones 2021-08-18 11:32 ` [PATCH 0/4] KVM: arm64: Fix some races in CPU_ON PSCI call Marc Zyngier 2021-08-18 11:32 ` Marc Zyngier
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20210818085047.1005285-2-oupton@google.com \ --to=oupton@google.com \ --cc=alexandru.elisei@arm.com \ --cc=james.morse@arm.com \ --cc=jingzhangos@google.com \ --cc=kvm@vger.kernel.org \ --cc=kvmarm@lists.cs.columbia.edu \ --cc=maz@kernel.org \ --cc=pshier@google.com \ --cc=rananta@google.com \ --cc=ricarkol@google.com \ --cc=suzuki.poulose@arm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.