Re: [Qemu-devel] [PATCH v4 10/17] hw/intc/arm_gic: Restrict priority view

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Fri, May 01, 2015 at 06:50:36PM +0100, Peter Maydell wrote:
> From: Fabian Aggeler <aggelerf@ethz.ch>
> 
> GICs with Security Extensions restrict the non-secure view of the
> interrupt priority and priority mask registers.
> 
> Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
> Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
> Message-id: 1429113742-8371-15-git-send-email-greg.bellows@linaro.org
> [PMM: minor code tweaks; fixed missing masking in gic_set_priority_mask
> and gic_set_priority]
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>


> ---
>  hw/intc/arm_gic.c      | 63 ++++++++++++++++++++++++++++++++++++++++++++++----
>  hw/intc/arm_gic_kvm.c  |  2 +-
>  hw/intc/gic_internal.h |  3 ++-
>  3 files changed, 61 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
> index e3bbe9e..7c0ddc8 100644
> --- a/hw/intc/arm_gic.c
> +++ b/hw/intc/arm_gic.c
> @@ -233,8 +233,16 @@ uint32_t gic_acknowledge_irq(GICState *s, int cpu)
>      return ret;
>  }
>  
> -void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val)
> +void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val,
> +                      MemTxAttrs attrs)
>  {
> +    if (s->security_extn && !attrs.secure) {
> +        if (!GIC_TEST_GROUP(irq, (1 << cpu))) {
> +            return; /* Ignore Non-secure access of Group0 IRQ */
> +        }
> +        val = 0x80 | (val >> 1); /* Non-secure view */
> +    }
> +
>      if (irq < GIC_INTERNAL) {
>          s->priority1[irq][cpu] = val;
>      } else {
> @@ -242,6 +250,51 @@ void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val)
>      }
>  }
>  
> +static uint32_t gic_get_priority(GICState *s, int cpu, int irq,
> +                                 MemTxAttrs attrs)
> +{
> +    uint32_t prio = GIC_GET_PRIORITY(irq, cpu);
> +
> +    if (s->security_extn && !attrs.secure) {
> +        if (!GIC_TEST_GROUP(irq, (1 << cpu))) {
> +            return 0; /* Non-secure access cannot read priority of Group0 IRQ */
> +        }
> +        prio = (prio << 1) & 0xff; /* Non-secure view */
> +    }
> +    return prio;
> +}
> +
> +static void gic_set_priority_mask(GICState *s, int cpu, uint8_t pmask,
> +                                  MemTxAttrs attrs)
> +{
> +    if (s->security_extn && !attrs.secure) {
> +        if (s->priority_mask[cpu] & 0x80) {
> +            /* Priority Mask in upper half */
> +            pmask = 0x80 | (pmask >> 1);
> +        } else {
> +            /* Non-secure write ignored if priority mask is in lower half */
> +            return;
> +        }
> +    }
> +    s->priority_mask[cpu] = pmask;
> +}
> +
> +static uint32_t gic_get_priority_mask(GICState *s, int cpu, MemTxAttrs attrs)
> +{
> +    uint32_t pmask = s->priority_mask[cpu];
> +
> +    if (s->security_extn && !attrs.secure) {
> +        if (pmask & 0x80) {
> +            /* Priority Mask in upper half, return Non-secure view */
> +            pmask = (pmask << 1) & 0xff;
> +        } else {
> +            /* Priority Mask in lower half, RAZ */
> +            pmask = 0;
> +        }
> +    }
> +    return pmask;
> +}
> +
>  static uint32_t gic_get_cpu_control(GICState *s, int cpu, MemTxAttrs attrs)
>  {
>      uint32_t ret = s->cpu_ctlr[cpu];
> @@ -451,7 +504,7 @@ static uint32_t gic_dist_readb(void *opaque, hwaddr offset, MemTxAttrs attrs)
>          irq = (offset - 0x400) + GIC_BASE_IRQ;
>          if (irq >= s->num_irq)
>              goto bad_reg;
> -        res = GIC_GET_PRIORITY(irq, cpu);
> +        res = gic_get_priority(s, cpu, irq, attrs);
>      } else if (offset < 0xc00) {
>          /* Interrupt CPU Target.  */
>          if (s->num_cpu == 1 && s->revision != REV_11MPCORE) {
> @@ -669,7 +722,7 @@ static void gic_dist_writeb(void *opaque, hwaddr offset,
>          irq = (offset - 0x400) + GIC_BASE_IRQ;
>          if (irq >= s->num_irq)
>              goto bad_reg;
> -        gic_set_priority(s, cpu, irq, value);
> +        gic_set_priority(s, cpu, irq, value, attrs);
>      } else if (offset < 0xc00) {
>          /* Interrupt CPU Target. RAZ/WI on uniprocessor GICs, with the
>           * annoying exception of the 11MPCore's GIC.
> @@ -820,7 +873,7 @@ static MemTxResult gic_cpu_read(GICState *s, int cpu, int offset,
>          *data = gic_get_cpu_control(s, cpu, attrs);
>          break;
>      case 0x04: /* Priority mask */
> -        *data = s->priority_mask[cpu];
> +        *data = gic_get_priority_mask(s, cpu, attrs);
>          break;
>      case 0x08: /* Binary Point */
>          if (s->security_extn && !attrs.secure) {
> @@ -870,7 +923,7 @@ static MemTxResult gic_cpu_write(GICState *s, int cpu, int offset,
>          gic_set_cpu_control(s, cpu, value, attrs);
>          break;
>      case 0x04: /* Priority mask */
> -        s->priority_mask[cpu] = (value & 0xff);
> +        gic_set_priority_mask(s, cpu, value, attrs);
>          break;
>      case 0x08: /* Binary Point */
>          if (s->security_extn && !attrs.secure) {
> diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
> index c5a2f81..54f18df 100644
> --- a/hw/intc/arm_gic_kvm.c
> +++ b/hw/intc/arm_gic_kvm.c
> @@ -251,7 +251,7 @@ static void translate_priority(GICState *s, int irq, int cpu,
>      if (to_kernel) {
>          *field = GIC_GET_PRIORITY(irq, cpu) & 0xff;
>      } else {
> -        gic_set_priority(s, cpu, irq, *field & 0xff);
> +        gic_set_priority(s, cpu, irq, *field & 0xff, MEMTXATTRS_UNSPECIFIED);
>      }
>  }
>  
> diff --git a/hw/intc/gic_internal.h b/hw/intc/gic_internal.h
> index 81c764c..119fb81 100644
> --- a/hw/intc/gic_internal.h
> +++ b/hw/intc/gic_internal.h
> @@ -82,7 +82,8 @@ uint32_t gic_acknowledge_irq(GICState *s, int cpu);
>  void gic_complete_irq(GICState *s, int cpu, int irq);
>  void gic_update(GICState *s);
>  void gic_init_irqs_and_distributor(GICState *s);
> -void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val);
> +void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val,
> +                      MemTxAttrs attrs);
>  
>  static inline bool gic_test_pending(GICState *s, int irq, int cm)
>  {
> -- 
> 1.9.1
>