[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/4] xen/arm: do not use is_running to decide whether we can write directly to the LR registers
During context switch is_running is set for the next vcpu before the gic state is actually saved. This leads to possible nasty races when interrupts need to be injected after is_running is set to the next vcpu but before the currently running gic state has been saved from the previous vcpu. Introduce a new gic_running internal variable to precisely determine which one is the vcpu currently using the gic. Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> --- xen/arch/arm/gic.c | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c index 0ecc0f1..88f2d3a 100644 --- a/xen/arch/arm/gic.c +++ b/xen/arch/arm/gic.c @@ -53,6 +53,7 @@ static irq_desc_t irq_desc[NR_IRQS]; static DEFINE_PER_CPU(irq_desc_t[NR_LOCAL_IRQS], local_irq_desc); static DEFINE_PER_CPU(uint64_t, lr_mask); static gic_callback_fn_t gic_callbacks[NR_IRQS]; +static struct vcpu *gic_running; unsigned nr_lrs; @@ -70,6 +71,7 @@ void gic_save_state(struct vcpu *v) for ( i=0; i<nr_lrs; i++) v->arch.gic_lr[i] = GICH[GICH_LR + i]; v->arch.lr_mask = this_cpu(lr_mask); + gic_running = NULL; spin_unlock_irq(&gic.lock); /* Disable until next VCPU scheduled */ GICH[GICH_HCR] = 0; @@ -81,12 +83,16 @@ void gic_restore_state(struct vcpu *v) int i; if ( is_idle_vcpu(v) ) + { + gic_running = v; return; + } spin_lock_irq(&gic.lock); this_cpu(lr_mask) = v->arch.lr_mask; for ( i=0; i<nr_lrs; i++) GICH[GICH_LR + i] = v->arch.gic_lr[i]; + gic_running = v; spin_unlock_irq(&gic.lock); GICH[GICH_HCR] = GICH_HCR_EN; isb(); @@ -481,7 +487,7 @@ void gic_set_guest_irq(struct vcpu *v, unsigned int virtual_irq, spin_lock_irqsave(&gic.lock, flags); - if ( v->is_running && list_empty(&v->arch.vgic.lr_pending) ) + if ( v == gic_running && list_empty(&v->arch.vgic.lr_pending) ) { i = find_first_zero_bit(&this_cpu(lr_mask), nr_lrs); if (i < nr_lrs) { -- 1.7.2.5 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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