From 5e0dd79ae85e1e5581059d9e1c52662c5b90e7df Mon Sep 17 00:00:00 2001
From: Josh Cartwright <joshc@ni.com>
Date: Thu, 11 Feb 2016 11:54:01 -0600
Subject: [PATCH] KVM: arm/arm64: downgrade preempt_disable()d region to
migrate_disable()
References: SLE Realtime Extension
Patch-mainline: Queued in subsystem maintainer repository
Git-commit: d13ac2a9d436b53b0178817f1568b1fc17031597
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mel Gorman <mgorman@suse.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 5c8bdb6d3f53..2a16f694bcd5 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -773,7 +773,7 @@ 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);
@@ -822,7 +822,7 @@ 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;
}
@@ -894,7 +894,7 @@ 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