diff options
Diffstat (limited to 'features/rt/KVM-arm-arm64-downgrade-preempt_disable-d-region-to-.patch')
| -rw-r--r-- | features/rt/KVM-arm-arm64-downgrade-preempt_disable-d-region-to-.patch | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/features/rt/KVM-arm-arm64-downgrade-preempt_disable-d-region-to-.patch b/features/rt/KVM-arm-arm64-downgrade-preempt_disable-d-region-to-.patch new file mode 100644 index 00000000..b42375b5 --- /dev/null +++ b/features/rt/KVM-arm-arm64-downgrade-preempt_disable-d-region-to-.patch @@ -0,0 +1,58 @@ +From 67396da80e5247521bb3a295c0a17ea970b143d6 Mon Sep 17 00:00:00 2001 +From: Josh Cartwright <joshc@ni.com> +Date: Thu, 11 Feb 2016 11:54:01 -0600 +Subject: [PATCH 175/191] KVM: arm/arm64: downgrade preempt_disable()d region + to migrate_disable() + +kvm_arch_vcpu_ioctl_run() disables the use of preemption when updating +the vgic and timer states to prevent the calling task from migrating to +another CPU. It does so to prevent the task from writing to the +incorrect per-CPU GIC distributor registers. + +On -rt kernels, it's possible to maintain the same guarantee with the +use of migrate_{disable,enable}(), with the added benefit that the +migrate-disabled region is preemptible. Update +kvm_arch_vcpu_ioctl_run() to do so. + +Cc: Christoffer Dall <christoffer.dall@linaro.org> +Reported-by: Manish Jaggi <Manish.Jaggi@caviumnetworks.com> +Signed-off-by: Josh Cartwright <joshc@ni.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + arch/arm64/kvm/arm.c | 6 +++--- + 1 file changed, 3 insertions(+), 3 deletions(-) + +diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c +index 7f06ba76698d..f9318256d6fb 100644 +--- a/arch/arm64/kvm/arm.c ++++ b/arch/arm64/kvm/arm.c +@@ -737,7 +737,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) + * involves poking the GIC, which must be done in a + * non-preemptible context. + */ +- preempt_disable(); ++ migrate_disable(); + + kvm_pmu_flush_hwstate(vcpu); + +@@ -786,7 +786,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) + kvm_timer_sync_user(vcpu); + kvm_vgic_sync_hwstate(vcpu); + local_irq_enable(); +- preempt_enable(); ++ migrate_enable(); + continue; + } + +@@ -858,7 +858,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) + /* Exit types that need handling before we can be preempted */ + handle_exit_early(vcpu, ret); + +- preempt_enable(); ++ migrate_enable(); + + /* + * The ARMv8 architecture doesn't give the hypervisor +-- +2.19.1 + |