[Xen-devel] [PATCH v2] 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>

---

Changes in v2:
- rebase on staging

diff --git a/xen/arch/arm/vgic-v2.c b/xen/arch/arm/vgic-v2.c
index 2c73133..3079901 100644
--- a/xen/arch/arm/vgic-v2.c
+++ b/xen/arch/arm/vgic-v2.c
@@ -494,11 +494,10 @@ static int vgic_v2_distr_mmio_write(struct vcpu *v, 
mmio_info_t *info,
         return 0;
 
     case VRANGE32(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 VRANGE32(GICD_IPRIORITYR, GICD_IPRIORITYRN):
     {
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 985e866..6011e9e 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -621,11 +621,10 @@ static int __vgic_v3_distr_common_mmio_write(const char 
*name, struct vcpu *v,
         return 0;
 
     case VRANGE32(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 VRANGE32(GICD_IPRIORITYR, GICD_IPRIORITYRN):
     {

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