Hi Andre,
On 05/03/18 16:03, Andre Przywara wrote:
Normally there is only one GICv3 redistributor region, and we use
that for DomU guests using a GICv3.
Explain the background in a comment and why we need to keep the number
of hardware regions for Dom0.
Signed-off-by: Andre Przywara <andre.przyw...@linaro.org>
Acked-by: Julien Grall <julien.gr...@arm.com>
Cheers,
---
Changelog RFC ... v1:
- Keep GUEST_GICV3_RDIST_REGIONS symbol around, just extend comments
xen/arch/arm/vgic-v3.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 2ad8a6be62..d5b34a7d0f 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -1632,6 +1632,16 @@ static int vgic_v3_vcpu_init(struct vcpu *v)
static inline unsigned int vgic_v3_rdist_count(struct domain *d)
{
+ /*
+ * Normally there is only one GICv3 redistributor region.
+ * The GICv3 DT binding provisions for multiple regions, since there are
+ * platforms out there which need those (multi-socket systems).
+ * For Dom0 we have to live with the MMIO layout the hardware provides,
+ * so we have to copy the multiple regions - as the first region may not
+ * provide enough space to hold all redistributors we need.
+ * However DomU get a constructed memory map, so we can go with
+ * the architected single redistributor region.
+ */
return is_hardware_domain(d) ? vgic_v3_hw.nr_rdist_regions :
GUEST_GICV3_RDIST_REGIONS;
}
@@ -1692,7 +1702,7 @@ static int vgic_v3_domain_init(struct domain *d)
{
d->arch.vgic.dbase = GUEST_GICV3_GICD_BASE;
- /* XXX: Only one Re-distributor region mapped for the guest */
+ /* A single Re-distributor region is mapped for the guest. */
BUILD_BUG_ON(GUEST_GICV3_RDIST_REGIONS != 1);
d->arch.vgic.rdist_stride = GUEST_GICV3_RDIST_STRIDE;
--
Julien Grall
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