[PATCH v2 05/15] xen/arm: vgic-v3: Correctly implement read into GICR_NSACR

[Julien Grall <julien.grall@linaro.org>]

The 32-bit register GICR_NSACR is RAZ/WI on non-secure state. Therefore
we should not inject a data abort to the guest.

Signed-off-by: Julien Grall <julien.grall@linaro.org>

---
    This patch should be backport to Xen 4.5. The current implementation will
    inject a data abort into the guest.

    Changes in v2:
        - Patch added
---
 xen/arch/arm/vgic-v3.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 1145972..2c14717 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -530,8 +530,9 @@ static int vgic_v3_rdistr_sgi_mmio_read(struct vcpu *v, mmio_info_t *info,
         vgic_unlock_rank(v, rank, flags);
         return 1;
     case GICR_NSACR:
-        if ( dabt.size != DABT_WORD ) goto bad_width;
-        return 1;
+        /* We do not implement security extensions for guests, read zero */
+        goto read_as_zero_32;
+
     default:
         printk(XENLOG_G_ERR
                "%pv: vGICR: SGI: read r%d offset %#08x\n not found",
-- 
2.1.4