xen/arm: gic: Make sure the number of interrupt lines is valid before using it

GICv2 and GICv3 supports up to 1020 interrupts. However, the value computed
from GICD_TYPER.ITLinesNumber can be up to 1024. On GICv3, we will end up to
write in reserved registers that are right after the IROUTERs one as the
value is not capped early enough.

Cap the number of interrupts as soon as we compute it so we know we can
safely using it afterwards.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reported-by: Jan-Peter Larsson <Jan-Peter.Larsson@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-Acked-by: Juergen Gross <jgross@suse.com>
(cherry picked from commit 30f5047b2c4e577436b505ba7627f34c3be02014)

diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index d2dcafb6a335921af66bf1e40212d064c1c2c0ec..d01b9c6aab334244a3b70c9c890beca3b898e820 100644 (file)
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -353,6 +353,10 @@ static void __init gicv2_dist_init(void)
 
     type = readl_gicd(GICD_TYPER);
     nr_lines = 32 * ((type & GICD_TYPE_LINES) + 1);
+    /* Only 1020 interrupts are supported */
+    nr_lines = min(1020U, nr_lines);
+    gicv2_info.nr_lines = nr_lines;
+
     gic_cpus = 1 + ((type & GICD_TYPE_CPUS) >> 5);
     printk("GICv2: %d lines, %d cpu%s%s (IID %8.8x).\n",
            nr_lines, gic_cpus, (gic_cpus == 1) ? "" : "s",
@@ -377,9 +381,6 @@ static void __init gicv2_dist_init(void)
     for ( i = 32; i < nr_lines; i += 32 )
         writel_gicd(~0x0, GICD_ICENABLER + (i / 32) * 4);
 
-    /* Only 1020 interrupts are supported */
-    gicv2_info.nr_lines = min(1020U, nr_lines);
-
     /* Turn on the distributor */
     writel_gicd(GICD_CTL_ENABLE, GICD_CTLR);
 }

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index a6ed0d8f22ec1576d747729741f7e85b26cf4425..f53a3fe65ebce8ba3a8aefba0fb8bb4be45175ee 100644 (file)
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -609,6 +609,10 @@ static void __init gicv3_dist_init(void)
     if ( type & GICD_TYPE_LPIS )
         gicv3_lpi_init_host_lpis(GICD_TYPE_ID_BITS(type));
 
+    /* Only 1020 interrupts are supported */
+    nr_lines = min(1020U, nr_lines);
+    gicv3_info.nr_lines = nr_lines;
+
     printk("GICv3: %d lines, (IID %8.8x).\n",
            nr_lines, readl_relaxed(GICD + GICD_IIDR));
 
@@ -648,9 +652,6 @@ static void __init gicv3_dist_init(void)
 
     for ( i = NR_GIC_LOCAL_IRQS; i < nr_lines; i++ )
         writeq_relaxed(affinity, GICD + GICD_IROUTER + i * 8);
-
-    /* Only 1020 interrupts are supported */
-    gicv3_info.nr_lines = min(1020U, nr_lines);
 }
 
 static int gicv3_enable_redist(void)