system-arm: Fix GICv3 in multi-cluster configuration

Current way of initializing GICv3 in the gem5 bootloader doesn't
work when there is a PE labelled with non-zero Aff1, Aff2 or Aff3
in the MPIDR_EL1 register
(For example in a multi-cluster configuration).

This is because the bootloader is considering Aff0 only

mrs x0, mpidr_el1
// extract the primary CPU.
ldr x1, =0xff00ffffff
and    x2, x0, #0xff // use Aff0 as cpuid for now...

With this patch we are solving the issue, by considering
every affinity number. Now the primary cpu is the cpu with

Aff3..Aff0 = 0.

The bootloader was also using Aff0 (stored in x2, see above)
to let every CPU index their own redistributor memory mapped frames.
In this model every secondary CPU was in charge of initializing
their own redistributor registers.

This can't be used anymore as we have a tuple of affinity
numbers now rather than a single flat index.

We are addressing the issue by letting the primary cpu initialize
every redistributor in the system. This is done by iterating
over consecutive frames and by reading GICR_TYPER.Last, which
is set to 1 if the current frame is the last one.

Change-Id: I2bcad286c2282bf1c47618e5391bf1c2e2b27013
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59393
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

system/arm/bootloader/arm64/boot.S

@@ -74,23 +74,26 @@ _start:
         // extract the primary CPU.
         ldr x1, =0xff00ffffff
 #ifdef GICV3
-        and	x2, x0, #0xff // use Aff0 as cpuid for now...
         tst	x0, x1 // check for cpuid==zero
-        b.ne	1f // secondary CPU
+        b.ne	2f // secondary CPU
 
         ldr	x1, =GIC_DIST_BASE // GICD_CTLR
         mov	w0, #7 // EnableGrp0 | EnableGrp1NS | EnableGrp1S
         str	w0, [x1]
 
 
-1:      ldr	x1, =GIC_REDIST_BASE + 0x10000 + 0x80 // GICR_IGROUPR0
-        // 128K for each redistributor, 256K strided...
-        mov	x3, #1 << 18 // GICv4
-        mul	x3, x3, x2
-        add	x1, x1, x3
+        ldr	x1, =GIC_REDIST_BASE
+        mov	x2, #1 << 18 // GICv4
         mov	w0, #~0 // Grp1 interrupts
-        str	w0, [x1], #4
-        b.ne	2f // Only local interrupts for secondary CPUs
+1:      add	x5, x1, #0x10000 // SGI base
+        str	w0, [x5, #0x80] // GICR_IGROUPR0
+        ldr	w4, [x1, #0x8] // GICR_TYPER
+        add	x1, x1, x2 // Point to next redistributor
+        // Check GICR_TYPER.Last, which is set to 1
+        // if this is the last redistributor
+        ands	w4, w4, #0x10
+        b.eq	1b // Branch back if not last redistributor
+
         ldr	x1, =GIC_DIST_BASE + 0x84 // GICD_IGROUPR
         str	w0, [x1], #4
         str	w0, [x1], #4