[XEN v5 04/11] xen/Arm: vGICv3: Adapt emulation of GICR_TYPER for AArch32

[Ayan Kumar Halder <ayan.kumar.halder@amd.com>]

Refer ARM DDI 0487I.a ID081822, G8-9650, G8.2.113
Aff3 does not exist on AArch32.
Also, refer ARM DDI 0406C.d ID040418, B4-1644, B4.1.106
Aff3 does not exist on Armv7 (ie arm32).

Thus, access to aff3 has been protected with "#ifdef CONFIG_ARM_64".
Also, v->arch.vmpidr is a 32 bit register on AArch32. So, we have assigned it to
'uint64_t vmpidr' to perform the shifts.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Acked-by: Julien Grall <jgrall@amazon.com>
---

Changes from :-
v1 - Assigned v->arch.vmpidr to "uint64_t vmpdir". Then, we can use 
MPIDR_AFFINITY_LEVEL macros to extract the affinity value.

v2 - 1. "MPIDR_AFFINITY_LEVEL(vmpidr, 3)" is contained within
"#ifdef CONFIG_ARM_64".
2. Updated commit message.

v3 - 1. Added an inline comment to explain type widening for v->arch.vmpidr.
2. Updated the commit message. Added Rb.

v4 - 1. Added Ack.

 xen/arch/arm/vgic-v3.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 3f4509dcd3..e0b636b95f 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -191,12 +191,20 @@ static int __vgic_v3_rdistr_rd_mmio_read(struct vcpu *v, mmio_info_t *info,
     case VREG64(GICR_TYPER):
     {
         uint64_t typer, aff;
+        /*
+         * This is to enable shifts greater than 32 bits which would have
+         * otherwise caused overflow (as v->arch.vmpidr is 32 bit on AArch32).
+         */
+        uint64_t vmpidr = v->arch.vmpidr;
 
         if ( !vgic_reg64_check_access(dabt) ) goto bad_width;
-        aff = (MPIDR_AFFINITY_LEVEL(v->arch.vmpidr, 3) << 56 |
-               MPIDR_AFFINITY_LEVEL(v->arch.vmpidr, 2) << 48 |
-               MPIDR_AFFINITY_LEVEL(v->arch.vmpidr, 1) << 40 |
-               MPIDR_AFFINITY_LEVEL(v->arch.vmpidr, 0) << 32);
+        aff = (
+#ifdef CONFIG_ARM_64
+               MPIDR_AFFINITY_LEVEL(vmpidr, 3) << 56 |
+#endif
+               MPIDR_AFFINITY_LEVEL(vmpidr, 2) << 48 |
+               MPIDR_AFFINITY_LEVEL(vmpidr, 1) << 40 |
+               MPIDR_AFFINITY_LEVEL(vmpidr, 0) << 32);
         typer = aff;
         /* We use the VCPU ID as the redistributor ID in bits[23:8] */
         typer |= v->vcpu_id << GICR_TYPER_PROC_NUM_SHIFT;
-- 
2.17.1