| Message ID | 1484765648-32493-1-git-send-email-julien.grall@arm.com |
|---|---|
| State | New |
| Headers | show |
On Wed, 18 Jan 2017, Julien Grall wrote: > >From the GICv3 spec (IHI069C) section 4.1.1: > "The effects of reading ICC_IAR0_EL1 and ICC_IAR1_EL1 on the state of a > returned INTID are not guaranteed to be visible until after the execution > of a DSB". > > Because of the GIC is an external component, a dsb sy is required. > Without it the sysreg read may not have been made visible on the > redistributor. > > Signed-off-by: Julien Grall <julien.grall@arm.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> > --- > > This patch should be backported up to Xen 4.6. > --- > xen/arch/arm/gic-v3.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c > index 57ed9d9..955591b 100644 > --- a/xen/arch/arm/gic-v3.c > +++ b/xen/arch/arm/gic-v3.c > @@ -459,7 +459,11 @@ static void gicv3_dir_irq(struct irq_desc *irqd) > > static unsigned int gicv3_read_irq(void) > { > - return READ_SYSREG32(ICC_IAR1_EL1); > + unsigned int irq = READ_SYSREG32(ICC_IAR1_EL1); > + > + dsb(sy); > + > + return irq; > } > > static inline uint64_t gicv3_mpidr_to_affinity(int cpu) > -- > 1.9.1 >
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c index 57ed9d9..955591b 100644 --- a/xen/arch/arm/gic-v3.c +++ b/xen/arch/arm/gic-v3.c @@ -459,7 +459,11 @@ static void gicv3_dir_irq(struct irq_desc *irqd) static unsigned int gicv3_read_irq(void) { - return READ_SYSREG32(ICC_IAR1_EL1); + unsigned int irq = READ_SYSREG32(ICC_IAR1_EL1); + + dsb(sy); + + return irq; } static inline uint64_t gicv3_mpidr_to_affinity(int cpu)
From the GICv3 spec (IHI069C) section 4.1.1: "The effects of reading ICC_IAR0_EL1 and ICC_IAR1_EL1 on the state of a returned INTID are not guaranteed to be visible until after the execution of a DSB". Because of the GIC is an external component, a dsb sy is required. Without it the sysreg read may not have been made visible on the redistributor. Signed-off-by: Julien Grall <julien.grall@arm.com> --- This patch should be backported up to Xen 4.6. --- xen/arch/arm/gic-v3.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)