[Xen-devel] [PATCH] ignore writes to GICD_ICACTIVER ... GICD_ICACTIVERN

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Injecting a fault to the guest just because it is writing to one of the
GICD_ICACTIVER registers, which are part of the GICv2 and GICv3 specs,
is harsh. Additionally it causes recent linux kernels to fail to boot on
Xen.

Ignore writes to GICD_ICACTIVER ... GICD_ICACTIVERN instead, to solve
the boot issue and for backportability. However implementing the
registers properly might a better long term solution.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

diff --git a/xen/arch/arm/vgic-v2.c b/xen/arch/arm/vgic-v2.c
index b5a8f29..bf9f239 100644
--- a/xen/arch/arm/vgic-v2.c
+++ b/xen/arch/arm/vgic-v2.c
@@ -315,11 +315,10 @@ static int vgic_v2_distr_mmio_write(struct vcpu *v, 
mmio_info_t *info)
         return 0;
 
     case GICD_ICACTIVER ... GICD_ICACTIVERN:
-        if ( dabt.size != DABT_WORD ) goto bad_width;
-        printk(XENLOG_G_ERR
+        gdprintk(XENLOG_DEBUG,
                "%pv: vGICD: unhandled word write %#"PRIregister" to 
ICACTIVER%d\n",
                v, *r, gicd_reg - GICD_ICACTIVER);
-        return 0;
+        goto write_ignore_32;
 
     case GICD_ITARGETSR ... GICD_ITARGETSR + 7:
         /* SGI/PPI target is read only */
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 45a46c3..e115027 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -412,11 +412,10 @@ static int __vgic_v3_distr_common_mmio_write(const char 
*name, struct vcpu *v,
         return 0;
 
     case GICD_ICACTIVER ... GICD_ICACTIVERN:
-        if ( dabt.size != DABT_WORD ) goto bad_width;
-        printk(XENLOG_G_ERR
+        gdprintk(XENLOG_DEBUG,
                "%pv: %s: unhandled word write %#"PRIregister" to 
ICACTIVER%d\n",
                v, name, *r, reg - GICD_ICACTIVER);
-        return 0;
+        goto write_ignore_32;
 
     case GICD_IPRIORITYR ... GICD_IPRIORITYRN:
         if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto bad_width;

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