53 lines
1.8 KiB
Diff
53 lines
1.8 KiB
Diff
From: Josh Cartwright <joshc@ni.com>
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Date: Thu, 11 Feb 2016 11:54:01 -0600
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Subject: KVM: arm/arm64: downgrade preempt_disable()d region to migrate_disable()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz
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kvm_arch_vcpu_ioctl_run() disables the use of preemption when updating
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the vgic and timer states to prevent the calling task from migrating to
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another CPU. It does so to prevent the task from writing to the
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incorrect per-CPU GIC distributor registers.
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On -rt kernels, it's possible to maintain the same guarantee with the
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use of migrate_{disable,enable}(), with the added benefit that the
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migrate-disabled region is preemptible. Update
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kvm_arch_vcpu_ioctl_run() to do so.
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Cc: Christoffer Dall <christoffer.dall@linaro.org>
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Reported-by: Manish Jaggi <Manish.Jaggi@caviumnetworks.com>
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Signed-off-by: Josh Cartwright <joshc@ni.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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virt/kvm/arm/arm.c | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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--- a/virt/kvm/arm/arm.c
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+++ b/virt/kvm/arm/arm.c
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@@ -700,7 +700,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
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* involves poking the GIC, which must be done in a
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* non-preemptible context.
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*/
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- preempt_disable();
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+ migrate_disable();
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kvm_pmu_flush_hwstate(vcpu);
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@@ -749,7 +749,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
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kvm_timer_sync_hwstate(vcpu);
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kvm_vgic_sync_hwstate(vcpu);
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local_irq_enable();
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- preempt_enable();
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+ migrate_enable();
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continue;
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}
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@@ -827,7 +827,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
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/* Exit types that need handling before we can be preempted */
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handle_exit_early(vcpu, run, ret);
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- preempt_enable();
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+ migrate_enable();
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ret = handle_exit(vcpu, run, ret);
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}
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